A new user-memory module owns every kernel touch of a user buffer:
copyFromUser, the new copyToUser, and the resolve behind both. The walk
accumulates the U/S and writable bits down all four levels with the MMU's
own AND rule — folding a 2 MiB leaf in before it resolves and refusing a
1 GiB leaf outright — so a copy honours what ring 3 itself would be
allowed, closing the presence-only trust model the IPC layer carried since
bring-up. It then confirms the frame is physmap-backed, because that is how
the copy reaches it: an mmio_map'd BAR passes the permission walk and would
otherwise fault ring 0 on an alias the physmap never mapped, on the IPC path
as much as the new one.
The nine stragglers that dereferenced user pointers raw now route through
it, so a bad pointer returns -EFAULT where it used to fault the kernel.
The write direction restructures its callees around kernel bounce buffers:
scheduler and devices-broker enumerate from a slot cursor (a task exiting
between chunks can neither duplicate nor lose an entry), klog_read drains
the ring in chunks, and fs_node stages headers and names contiguously.
fs_resolve copies out before installing the endpoint handle, so a faulting
copy cannot strand a capability; its out-capacity bound no longer adds an
unbounded ring-3 length to the base, which wrapped and trapped the kernel's
own overflow check. debug_write reads the caller's message once.
Suite 107/107 (new user-memory case: seven bad pointers refused, each
paired with a sound call that must still succeed).
/etc/init.csv and /etc/devices.csv become /system/configuration/*.csv (the
repo's etc/ moves to system/configuration/, mirroring the runtime tree),
/var/log becomes /system/logs, and /mnt/usb becomes /volumes/usb. The
kernel VFS gains a carve-out so FAT may serve exactly /system/configuration
and /system/logs beneath the initrd-backed /system while /system and /test
themselves stay unshadowable; FAT's single /var mount splits into those two
rewritten mounts. The kvfs readdir check learns /system's third child and
the ramdisk spawn sweep skips the configuration tree.
Suite 106/106.
The /loop work list for the committed design set: Phase 0 baseline, PM
(unix-path flag-day), H1 copy discipline, P1 envelope + Channel, P2
registry + ServiceId retirement, P3 open grants, P4a-c protocol rebase,
H2 SMEP, HS sysret guard, H3 SMAP. Ten settled decisions from the
2026-07-31 grounding pass, two corrected on review: every packet carries
the envelope header folded (headerless events rejected), and bind/open
authorization is chain-attested identity (name alone rejected — ungated
spawn makes it a confused deputy). smep-smap.md gains the verified
straggler table: nine syscalls, klog_status the ninth, with the
callee-writer restructuring notes.
The security-track design set. communication.md is the model: four layers
(namespace / protocol / channel / transport), packets and signals, parties
addressed by the channel and objects by target, transports as replaceable
buffer+doorbell mechanisms. protocol-namespace.md is L3+L2: /protocol names
contracts, resolution establishes a channel, init is the registrar,
restriction is per-process namespace delegation (with the microphone-prompt
worked example), the envelope is the universal packet header, migration
P1-P5 retires ServiceId. file-system-hierarchy.md replaces the unix-FHS
spec with the danos-native tree (/applications, /protocol, /system,
/volumes) and its migration table. ipc.md is re-cut as the kernel-ipc
transport document. smep-smap.md designs the kernel hardening: copy
discipline for the eight raw user-pointer syscalls, then SMEP, then SMAP
as a permanent tripwire.
Five design-and-milestone notes for making danos programmable before Zig
self-hosts:
- python-on-danos: why CPython, the WASI precedent, static-only interop
- python-on-danos-milestones: P0–P5 (libc → seam → CPython → terminal+REPL →
danos module → process control + shell) with tests and exit criteria
- c-library-compatibility: the libdanos-c sysroot — musl computation lifted,
Zig plumbing over runtime; staged road to full coverage (fork never comes)
- character-devices-and-tty: stream nodes over the existing VFS; first device
is an in-memory loopback (COM1 off the critical path); no pty object — the
terminal serves its children directly
- dynamic-libraries: post-P5 D1–D4, application-layer only
The size doctrine runs through all of them: the OS stays lean (kernel in
kilobytes, services small and static, never linking the libc); applications
have their own budget.
The module-to-domain table in build-support duplicated what each
domain's build.zig already states with its addModule exports. userBinary
now resolves each named import by searching the packages the binary
declared in its own build.zig.zon (b.available_deps), which also makes
the zon the literal include path: an import can only be satisfied by a
domain the binary claims, and naming a module whose domain is missing
fails the build graph with the domain to declare. build-support is down
to the recipe alone. All build variants green; manifest unchanged.
Each shipped binary was registered twice in the root build (a
dependency/artifact line plus a bundled row repeating its name and
path). The uniform rows — dependency name = artifact name = boot-path
leaf — collapse into production_ship, one line per binary via the
service()/driver()/driverArtifact() helpers; only the genuinely
non-uniform entries stay spelled out (init's -Dserial, the -Ddiscovery
pick, the /etc data files). Selecting what goes into a build is now
selecting table rows, and an unselected package's build file is never
loaded. The boot manifest is set-identical; its order shifts (discovery
and the /etc entries move) — every lookup is by name, and the
boot-order QEMU smoke passes.
VT-d and AMD-Vi are x86 hardware, but lived in the architecture-neutral
kernel tree and leaked further: the core's public Kind enum named both
vendors, and the ACPI parser read the VT-d version/capability registers
(raw volatile MMIO inside table discovery). Now the vendor backends
live in architecture/x86_64/ behind architecture.iommu — the core hands
over the discovery facts plus an injected environment (frame allocation
+ the log sink, the same pattern enablePaging uses) and receives the
hardware vtable back, so the backends never import kernel internals and
an ARM port supplies its SMMU with no core change. Discovery keeps
table facts only; the live-unit register check moved into VT-d detect
(version reading zero now stays fail-open). The unused kindOf() is
gone. Log shapes the harness pins (iommu online, DANOS-IOMMU-FAULT)
are unchanged; all five IOMMU QEMU cases pass.
display-client and input-client (files and module names), so a service,
its wire contract, and its client never share a name: `display` the
service, `display-protocol` the contract, `display-client` a program's
view of it. The nine consumers' imports and their packages' declared
lists follow (regenerated from the source scan); build-support's
module_homes table carries the new names.
Every binary's build.zig now names precisely the modules its source
imports (derived by scanning each artifact's sources, transitively
through same-directory files), and its zon carries only the domains
those come from — kernel stays implicit (the root shim + link script
live there). build-support's userBinary resolves each name through one
module-to-domain table (module_homes); Domains/domains()/defaultImports
and the raw recipe entry point are deleted. An undeclared @import is a
compile error (verified: injecting @import("xkeyboard-config") into
logger fails with 'no module named ... available within module
program'), and e.g. xkeyboard-config now appears in exactly two
manifests — the two keyboard drivers. Availability never bloated the
emitted binaries (Zig compiles only what a program imports); this makes
the declared interfaces honest. Production and -Dtest-case manifests
byte-identical; all build variants and standalone package builds
green.
The 13 /test fixtures and the acpi/fdt discovery pair are .lazy in the
root zon, resolved with b.lazyDependency only when a build actually
bundles them: a plain `zig build` neither compiles the fixtures nor
loads their build files, and only the -Ddiscovery-selected package ever
loads. Fixture packages are uniform (dependency name = artifact name =
boot-path leaf), so the bundled list shrinks to a name loop. Production
manifest byte-identical; the -Dtest-case manifest carries the same 13
entries in the same order; -Ddiscovery=fdt exercises the lazy fdt path.
Discharges the plan's deferred what-this-buys #4.
initial_ramdisk's spawn-everything sweep counted the /etc data files
(devices.csv, init.csv) as spawnable programs — BadElf ever since the
boot tree started ferrying them — so it now counts only the /system and
/test trees. The init test waited for two raw user writes before
checking the last write for the heartbeat text; init's boot chatter
(heap ok, the /etc/init.csv lookup) satisfies the count long before the
first beat, so it now waits for the heartbeat itself. Both cases pass
again; these failures predate the build-packages work.
The checklist (with the Intel UHD 750 worked example) existed only as
an untracked file in the main checkout — the plan referenced it but no
branch could see it. It lands here with its build step rewritten
against the finished package template: create the driver's own
build.zig/zon from the pci-bus template, then one dependency + one
boot-tree row + one zon line in the root build. devices-csv.md's
adding-a-driver section and the plan's checklist references point at
it again.
The plan doc's status records completion (all waves + phase 3) and its
execution notes describe the finished shape; the fresh-session pointer
names build-support's userBinary instead of the deleted
addUserBinaryImpl, and the size-check carry-along note is discharged.
README gains the build/ directory in the layout tree and splits the
source-map row across root build.zig / build/images.zig /
build/qemu.zig. testing.md points at the distributed per-package test
steps; threading.md, threading-plan.md, driver-model.md, efi.md,
display.md, system-requirements.md, and devices-csv.md's adding-a-
driver checklist stop describing the pre-package build.
Wave C dropped the .threaded flag the old addThreadedUserBinary call
carried, so thread-test compiled single_threaded: the heap mutex was
compiled out and atomics lowered to plain ops while the fixture spawns
real kernel threads — the QEMU thread-alloc case caught it (corruption
under concurrent allocation), and the completion review confirmed the
same finding independently. All 12 QEMU thread cases pass again.
build/images.zig owns everything between built binaries and a bootable
volume: the FHS zig-out install tree, boot manifest + capsule, both
FAT32 images, the release ISO, and their check steps. build/qemu.zig
owns run-x86-64 / run-x86-64-gpu and the OVMF probing. The root
build.zig (461 lines, from 1,242 pre-split) now only decides what
ships: kernel + loader, the package list, the bundled boot tree, and
the aggregate test step. The stale commented-out run scaffold is gone.
Boot-image file list unchanged; check-fat-image and check-iso-image
both green.
All thirteen /test/system/services fixtures convert on the pci-bus
template (thread-test threaded; crash-test/device-list/pci-cap-test/
iommu-fault-test carrying their protocol and PCI extras). With the last
addUserBinary caller gone, the root build's wrapper functions and its
default-imports plumbing are deleted — every user binary now reaches
the shared recipe only through its own package. Production boot-image
file list unchanged; a -Dtest-case build bundles the fixtures exactly
as before.
ps2-bus (bus + keyboard + mouse artifacts from one package),
usb-xhci-bus, usb-hid (keyboard + mouse), usb-storage, and virtio-gpu
convert on the pci-bus template. Their unit tests — PS/2 decode, HID
boot reports, Bulk-Only Transport/SCSI encodings, and the virtio-gpu
size checks the plan flagged as a wave carry-along — move into their
packages; the root aggregate delegates. Boot-image file list
unchanged.
init, fat, display, display-demo, device-manager, input, logger, and
the two discovery fillers (acpi, fdt — each exporting an artifact named
"discovery"; the root -Ddiscovery picks which ships) convert to binary
packages on the pci-bus template. init's serial heartbeat flag rides
the dependency options (the root forwards its -Dserial). fat's and
display's unit tests move into their packages and the root aggregate
delegates to them. Boot-image file list unchanged.
Review findings: the plan doc claimed no implementation existed, had the
domain dependency order wrong (kernel depends on protocol; device on
kernel + protocol + csv), never placed the three shared contracts, and
named a nonexistent new-driver-checklist.md. Its status now records the
implemented phases (and the deliberate pci-bus-first pilot), the target
shape carries the contract placements and the path-dependency-only
constraint on the kernel package's out-of-root abi export, and the
execution notes describe the post-pilot build for whichever session
runs the remaining waves. README's repo layout gains build-support/
and the packages-note; driver-model, threading, system-requirements,
and the two display plan docs stop citing root build.zig for recipe
facts that now live in build-support.
Review findings from the pilot: the 17-module default import set was
maintained twice (root's array and build-support's userBinary) — drift
would silently make packaged binaries differ from root-built ones. It
now lives once, as build-support.defaultImports; root and userBinary
both draw from it, and root's user-binary wrapper names the shim +
link script through the kernel package like build-support does.
The root aggregate test step likewise duplicated the library domains'
14 test definitions; it now depends on each domain's own standalone
test step (host-only, so root's -Dtarget/-Doptimize deliberately do
not reach them), and the client domain gains an empty test step for
uniformity. Boot-image file list unchanged.
build-support gains the domains-based userBinary: the default import set
(the library/kernel concern modules, driver/service clients, mmio,
acpi-ids, xkeyboard-config) is assembled from the domain packages, and
the root shim + user link script come from the kernel package directory.
system/drivers/pci-bus is the first binary package: a ~15-line
declarative build.zig naming only its extras (device-manager-protocol,
pci-class); the root build consumes the artifact for the boot image and
the driver also builds standalone from its own directory. Boot-image
file list unchanged.
Each library domain (kernel, device, client, protocol, csv,
xkeyboard-config) now owns a build.zig + build.zig.zon that wires and
exports its modules, with a standalone `zig build test` per domain.
The kernel package also exports abi (source stays in system/abi.zig) so
every consumer names one module instance. The root build swaps its
createModule calls for b.dependency(...).module(...) — no binary moves;
the root is the pilot consumer (docs/build-packages-plan.md). Path
dependencies deduplicate by resolved location, so the diamond
(root -> device -> kernel, root -> kernel) yields a single instance of
each module. Boot-image file list unchanged.
The shared user-binary recipe (freestanding target, root-shim wiring,
link-script and image-base settings) moves out of the root build into
build-support/, the package that is the single home for cross-cutting
build changes (docs/build-packages-plan.md). The root build's
addUserBinary/addThreadedUserBinary keep their signatures and delegate;
nothing else moves. Boot-image file list unchanged.
The second hardware backend. The IOMMU core, DMA-region capabilities, and
per-device enforcement are unchanged; this adds AMD-Vi (IVRS) as an
alternative to Intel VT-d (DMAR) under the same Backend vtable.
- parseIvrs records the IOMMU control-register base from the first IVHD;
the platform layer gains iommu_is_amd, and the core picks the backend by
vendor at init. VT-d and AMD-Vi are mutually exclusive on real hardware.
- iommu-amd.zig: a 2 MiB device table (every DTE zeroed = deny-all until a
device is claimed), AMD native-format page tables (4 KiB leaves), a
command buffer (INVALIDATE_DEVTAB_ENTRY / INVALIDATE_IOMMU_PAGES /
COMPLETION_WAIT) and an event log for faults. The DTE forwards
interrupts unmapped, so MSI passthrough works exactly as on VT-d.
- The boot log and the iommu self-test are now vendor-aware.
**UNTESTED on real AMD hardware** — danos is developed on Intel, so this
is validated only against QEMU's amd-iommu, and every log line and doc
says so. QEMU quirk handled: its amd-iommu does not observe the
COMPLETION_WAIT store form, but consumes the command ring synchronously on
the tail-register write, so invalidations are already applied by the time
we poll — the backend warns once and proceeds.
Cases: amd-iommu (detection + scratch-domain walker) and
amd-iommu-usb-storage (full storage stack through AMD device-table
translation with per-grant capabilities), both green. 106/106.
This completes the IOVA/IOMMU-enforcement track: per-device DMA domains on
both vendors, with buffers reachable only through delegated capabilities.
Replaces L2's interim DMA pool (every buffer reachable by every claimed
device) with true per-grant confinement: a device reaches only buffers
whose capability was delegated to its driver.
Kernel:
- DmaRegionObject (handle kind 2): a delegation token naming a dma_alloc'd
region, passable across processes on the IPC cap slot like an endpoint
or shared-memory object. Frames stay owned by the allocating address
space (freed on dma_free/teardown as before); the token carries a `dead`
flag so a stale downstream handle can no longer bind a freed region.
- dma_alloc gains the dma_shareable flag: it returns a capability handle
in r8 and every region is tracked in a registry. A task's own regions
auto-bind into the devices it claims (its rings just work); foreign
buffers are bound explicitly.
- dma_bind / dma_unbind / handle_close syscalls (51-53). dma_bind maps a
held region (or shared-memory) capability into a claimed device's domain;
it is idempotent. handle_close reclaims a table slot (raised 16 -> 32).
- dma_free and task death unmap a region from every domain and invalidate
BEFORE its frames return to the allocator — the stale-IOTLB use-after-
free window, closed structurally.
Protocols (flag-day): block gains attach, usb-transfer gains dma_attach —
each carries a region capability on the cap slot. fat allocates its bounce
buffer shareable and attaches it; usb-storage allocates its transport
buffers shareable, attaches them to the controller, and forwards fat's
capability downstream; usb-xhci-bus binds and closes; virtio-gpu binds its
shared scanout surface. The physical addresses on the wire are unchanged
(identity IOVA), so no register-programming code moved.
Cross-process DMA (fat -> usb-storage -> xHC) now flows only through
delegated capabilities. iommu-usb-storage / iommu-usb-hid / iommu-fault
all green under per-grant enforcement; 104/104 overall (fail-open paths
unchanged).
Replaces L1's shared blanket identity domain with a private translation
domain per claimed PCI function. A device now reaches only:
- the DMA pool: every dma_alloc'd region, mapped into every claimed
device's domain (poolAdd/poolRemove, driven from the dma_alloc and
dma_free syscalls). This keeps the cross-process buffer handoff
working (fat's bounce buffer reaches the xHC) while blocking the
kernel, page tables, process heaps, MMIO, and unallocated RAM.
- its own firmware reserved region (RMRR), seeded at confine time.
The pool is the honest interim: devices can still reach one another's
DMA buffers. The DMA-region capability layer (next) narrows it to
per-grant reachability.
dma_free unmaps from every domain and invalidates BEFORE the frames
return to the allocator, closing the stale-IOTLB use-after-free window.
Driver death tears down its domains (detach + free tables) before the
broker claims and DMA frames are released.
New iommu_fault_drain syscall (+ driver.iommuFaultDrain) forces pending
fault records to the log on demand. The new iommu-fault case proves it:
a claimed e1000e is programmed to DMA-fetch its TX ring from an unmapped
page; VT-d faults the access (bdf 00:03.0 addr 0x1000 reason 0x6) and the
system stays alive. 104/104.
First enforcement step of the IOVA track. A vendor-neutral IOMMU core
(iommu.zig) drives an Intel VT-d backend (iommu-intel.zig) to give DMA a
real translation layer instead of the fail-open free-for-all M16 left.
- Boot posture is now stated explicitly: "iommu online (Intel VT-d)"
with version/agaw/rmrr, or "none present - DMA fail-open (unisolated)".
- DMAR parsing extended to select the INCLUDE_PCI_ALL unit (real Intel
PCs put an iGPU-scoped unit first) and record single-path-endpoint
RMRRs; multi-hop scopes and extra DRHDs are counted and warned, never
silently dropped.
- Translation is enabled at boot into a blanket identity domain (all RAM
+ RMRRs, 2 MiB leaves). PCI functions are enumerated post-boot by the
ring-3 pci-bus driver, so a device is attached to the domain when its
driver claims it (confineDevice, with claim rollback if confinement
fails) and detached on driver death, before broker release and DMA
frame teardown. Unclaimed devices are non-present: their DMA faults.
- Interrupt remapping stays off, so MSI writes to 0xFEE00000 bypass
translation and the interrupt-driven xHC keeps working.
- devices-broker gains pciAddressOf (derives BDF from the config-space
ECAM offset), unclaim, and forEachPciFunction.
Faults are drained and logged rate-limited as DANOS-IOMMU-FAULT.
Cases: iommu extended (translation on, scratch-domain map/resolve/unmap,
zero idle faults); new iommu-usb-storage and iommu-usb-hid run the full
storage + input stacks through translated DMA with MSI intact. 103/103.
library/device/pci is now the complete generic floor a leaf PCI driver
needs, instead of just what virtio-gpu used:
- pci-class: capability IDs, MSI/MSI-X/power-management/PCI-Express
register layouts, extended-capability header decode (host-tested),
per-bit command constants, remaining header offsets.
- pci.Function: header accessors, disableBusMaster + interrupt-disable
helpers, findCapability, programMsi/disableMsi, MsiX vector-table
struct, ensurePowerStateD0, functionLevelReset (BAR save/restore),
extended-capability iterator.
Proven by the new pci-caps QEMU case: a pci-cap-test fixture claims an
extra e1000e (PM+MSI+PCIe+MSI-X, no danos driver) and readback-verifies
every surface, including the first driver-side use of msi_bind.
usb-xhci-bus converts from 8 ms event-ring polling to message-signalled
interrupts: plain MSI where offered (real Intel xHC), MSI-X entry 0
otherwise (qemu-xhci has no MSI capability), byte-identical polling as
fallback. The timer survives as a 250 ms port-reconcile/lost-edge tick —
real-hardware USB2 hub debounce still needs it. MSI setup runs BEFORE
controller bring-up: QEMU's xhci only registers the MSI-X vector as used
when IMAN.IE is written while MSI-X is already enabled; interrupts are
silently dropped otherwise (real hardware does not care about the order).
101/101 QEMU cases green; real-hardware smoke passed (mouse works,
boot 2026-07-23T174805Z, plain-MSI branch, vector 33).
ReleaseSafe kept full DWARF/symtab because nothing set strip on the
kernel module, bloating the flashable image to 2.4MB (~1.4MB of which
was debug info). Strip for every optimize mode except Debug, so
release builds shrink to ~900KB while debug builds keep symbols.
The 11 QEMU-suite fixtures lived mixed into system/services/ with their
binaries bundled at /system/tests/<name>. Now the repo path is the boot
path, like every real service: test/system/services/<name>. fat-test
moves out of the fat server's directory into its own; display-demo
stays a boot service.
- kernel VFS: setInitialRamdisk derives one read-only initrd mount per
top-level tree named by the ramdisk entry paths (/system, /test),
registers ancestors generically with self-parented roots, and refuses
backend shadowing of any initrd tree
- EFI loader: the fallback walk also enumerates \test (optional — a
volume without fixtures still boots); manifest and capsule unchanged
- path literals: vfs-test self-open + create probe, process-test
process_enumerate matches, the args-echo argv[0] expectation; the
kvfs case now covers the /test root end to end
- docs: DFHS /test rows, tree diagrams, loader prose, and the location
convention gain the third home; fixed the input-source link
100/100 QEMU cases pass.
An adversarial review of the reorg surfaced two doc inaccuracies:
- timers.md: a `time` code example still did `@import("runtime").time`, which
no longer compiles — the runtime aggregator was deleted. Now `@import("time")`.
(Reorg regression: the sweep rewrote `runtime.x` member access but not the
`@import("runtime")` form inside a fenced code block.)
- sysv.md: `callconv(system.kernel_abi)` named a non-existent `system` module;
`kernel_abi` lives in the boot-handoff contract (system/boot-handoff.zig),
imported as `boot_handoff`. Now `boot_handoff.kernel_abi`. (Pre-existing bug —
"system" was the file-path prefix mistaken for a module namespace — found and
fixed opportunistically.)
Rewrote the repository-layout and driver-model docs to describe the new tree —
library/kernel (the kernel32-style system library: syscall surface split by
concern), library/device (mmio/model/pci/usb/acpi/driver/block), library/client
(display, input service clients), library/protocol (wire contracts) — and swept
the reference docs off the retired runtime shim:
runtime.system.* -> logging.* / time.* / process.* / memory.*
runtime.dma.* / runtime.shared_memory.* / runtime.allocator -> memory.*
runtime.ipc/process/time/service/Thread/block/display/input -> the module name
runtime.device / runtime.device_manager -> driver
library/runtime/<file>.zig -> its new home (kernel/ client/ device/)
docs/README.md (repository layout + source map), docs/driver-model.md (the module
graph + import lists), and the concern/reference docs (ipc, threading, timers,
logging, power, process-lifecycle, device-manager, display, vdso, sysv, drivers,
input, vfs-protocol, coding-standards, ...) now reflect the split. "runtime" that
remains is the userspace-library *concept*, which is still accurate.
The historical plan docs (display-plan, display-v2-plan, threading-plan) and the
zig-self-hosting design note are left as point-in-time snapshots.
With every consumer migrated (C2), nothing imports `runtime` or `system` any
longer. Removed both shim files and their build.zig module definitions, dropped
the `runtime` entry from `default_imports`, and rewrote the per-binary root shim
(library/kernel/root.zig) to import `start` (_start + panic) and `logging`
(std_options) directly instead of through `runtime`.
addUserBinary/addThreadedUserBinary/addUserBinaryImpl lose their `runtime_module`
parameter; the root module now pulls the two modules it needs out of
`default_imports` via a small findImport helper.
The runtime dumping ground is gone: the userspace library is library/kernel
(concern modules), library/device (driver/pci/usb/block/model/mmio/acpi data),
library/client (display, input service clients), and library/protocol (wire
contracts). Consumers @import concern modules by name.
Verified: zig build, zig build test, and QEMU (smoke, thread-spawn, thread-mutex,
logger, display-native, device-manager, usb-storage, input).
Every user binary and the two device-logic library modules (pci, usb) now
`@import` the concern modules directly instead of aliasing through `runtime`:
runtime.ipc/process/time/service/input/block/display -> @import("<module>")
runtime.device / runtime.device_manager -> @import("driver")
runtime.fs -> @import("file-system")
runtime.Thread -> @import("thread").Thread
runtime.system.{write,writeRecord,klog*} -> logging.*
runtime.system.{sleep,timerOnce,wallClock,clock} -> time.*
runtime.system.{spawn*,kill,exit,yield,processes,...}-> process.*
runtime.system.{mmap,munmap,PROT_*} -> memory.*
runtime.dma.* / runtime.shared_memory.* / runtime.allocator -> memory.*
Each consumer keeps its own alias name (e.g. `const device = @import("driver")`),
so call sites are unchanged and there are no collisions with local `driver`
variables. build.zig now injects the concern modules into every user binary via
`default_imports`; pci/usb module import lists were updated to match.
The `runtime` and `system` shims remain for one more step (root.zig still uses
runtime); they are deleted in C5. Nothing but root.zig imports `runtime` now.
Verified: zig build, zig build test, and 17 QEMU cases (smoke, device-manager,
logger, fat-mount, fat-mutations, usb-storage, usb-hid, display-native,
virtio-gpu, input, thread-spawn, thread-mutex, process-kill, shared-memory,
driver-restart, acpi-ps2, pci-scan).
The one giant `runtime` module (with a `system.zig` that was itself a dumping
ground of unrelated syscalls) is split into directly-importable, flat concern
modules under library/kernel/:
system-call ipc memory process thread time logging file-system service start
(+ the device/service clients: device, device-manager, block, display, input)
system.zig is dissolved — its functions moved to their concern home (mmap ->
memory, spawn/kill/exit -> process, sleep/clock -> time, write/klog -> logging,
fs* -> file-system). `memory` merges heap+dma+shared-memory behind one flat API
(memory.allocator/dmaAlloc/sharedCreate/mmap), keeping heap's state and malloc
export single. The memory<->thread dependency cycle (heap needs Thread.Mutex,
thread needs mmap) is broken by having thread allocate its own stack via the raw
mmap syscall, so the module graph is a DAG.
This is the atomic step: all 42 internal cross-imports flip from relative to
module imports at once. `runtime.zig` and `system.zig` become thin re-export
SHIMS so the ~38 consumers keep compiling on `runtime.*` untouched; they migrate
to direct imports in C2, after which the shims are deleted (C5).
zig build + zig build test green; 14 QEMU cases pass (smoke, process,
process-kill, thread-spawn/join, logger, vfs, fat-mount, display-native,
usb-storage, virtio-gpu, device-manager, input, power-button).
First step of splitting the runtime dumping ground. Pure directory rename
(git mv library/runtime library/kernel) + the six build.zig path references
repointed. The module is still named "runtime" for now; the next commits split
it into concern modules (ipc, memory, process, time, logging, file-system, ...),
dissolve system.zig, and delete the runtime aggregator.
The library/kernel name follows the kernel32 model: it is the userspace library
that wraps the private kernel ABI, distinct from system/kernel/ (the kernel).
zig build green.
Follow-up cleanup of the just-moved kernel device code:
- power.zig -> acpi.zig. Its reboot() is built entirely on the FADT reset
register (acpi.power_information) plus the legacy 0xCF9/8042 fallbacks — it is
ACPI reboot, so it becomes acpi.reboot (the "P" in ACPI). platform.reboot
still delegates; soft-off/S5 stays the ring-3 acpi service's job as before.
- device-tree.zig -> fdt.zig. It is a discovery *backend* (the ARM/FDT parser,
a sibling of acpi.zig), not part of the model — renaming it to its actual
subject kills the confusing device-tree / device-model DeviceTree name clash
and makes acpi.zig + fdt.zig read as the two parallel backends.
- Flatten: device-model.zig, acpi.zig, fdt.zig, platform.zig move out of the
system/kernel/devices/ subdir up into system/kernel/, joining devices-broker.zig
(already flat). The kernel dir is a flat pile by convention (only architecture/
is a subdir), so the subdir — and its poor "devices" name — is gone.
Pure restructure; "platform" module name unchanged, all cross-file deps are
relative siblings that moved together. zig build + test green; smoke, discovery,
acpi-parse, acpi-ps2, acpi-report, power-button, orderly-shutdown, reboot pass.
With the shared device data (device-abi, pci-class, usb-abi, usb-ids, acpi-ids,
aml) now in library/device/, what remained in system/devices/ was purely
kernel-internal: the firmware-discovery machinery and the rich pointer-based
device model (platform, device-model, acpi, device-tree, power), reached only
through the "platform" module by three kernel files. It belongs with the kernel.
Move it to system/kernel/devices/. A pure relocation: the "platform" module
name is unchanged and every cross-dir dependency is a module import, so only the
one b.path and some comments move. The top-level split is now clean —
system/kernel/ is the kernel, library/device/ the shared device libraries,
system/{drivers,services} the userspace. The runtime /system/devices concept
(the virtual device tree) is unaffected; system/kernel/devices/ is its
implementation.
Also fixes two comment refs that still pointed device-abi at its pre-Wave-1a
home (system/devices/) — it lives at library/device/model/ now.
zig build + test green; smoke, discovery, acpi-parse, acpi-ps2, acpi-report pass.
mmio is device-driver code, so it joins the other domains under
library/device/mmio/ (module name "mmio" unchanged — a pure relocation, only
the build paths move). And its abbreviated function names are spelled out per
docs/coding-standards.md:
read -> readRegister mb -> memoryBarrier
write -> writeRegister rmb -> readMemoryBarrier
wmb -> writeMemoryBarrier
All call sites updated (virtio-gpu, usb-xhci-library, pci.Function); the two
display-driver placeholders import mmio but use nothing, so they're untouched.
Docs (driver-model graph, README layout, drivers.md, the FHS note) follow the
new path and names.
zig build + test green; virtio-gpu, display-native, display-reattach, usb-hid,
usb-hub, usb-storage, pci-scan pass.
Finish the direct-import convention: a protocol is now aliased to its module
name in snake_case in every file that imports one — consumers and the runtime
client wrappers alike. This kills the last of the alias variety (the generic
`protocol`, plus `power` and `transfer`), so `device_manager_protocol.Hello`
means the same thing everywhere and grepping a module name finds all its uses.
Pure rename (identifier uses only; prose references left untouched via a
guarded pattern). 14 files, 299/299 lines.
zig build + test green; 16 QEMU cases pass (smoke, device-manager,
driver-restart, device-list, pci-scan, usb-hid, usb-storage, display-service,
display-native, display-reattach, input, acpi-ps2, vfs, fat-mount,
power-button, orderly-shutdown).
Update the docs to match the reorganized tree:
- driver-model.md: the "Families" graph now shows library/device/<domain>/
(data + logic split) and library/protocol/ instead of the old bus/ + proto/
sketch; add the microkernel note (the kernel's one library/ import is the
device-abi data module) and the rule that a driver's hardware command set is
not a service-seam protocol.
- README.md "Repository layout": device-abi and the protocols move out of
system/ into library/device/ and library/protocol/; rewrite the "public
interface as a module" paragraph around the protocol tree and the device
domains; fix the source-map paths.
- Sweep every remaining stale path reference across docs/ to the moved files.
- Fix vfs-protocol.zig's own header (the standalone VFS server retired; the fat
server is the backend today).
zig build + test green.
power-protocol -> library/protocol/power/power-protocol.zig. Its two consumers
(init and the acpi discovery service) import it directly; the
runtime.power_protocol re-export and the runtime module import are dropped (no
runtime client speaks it). The now-empty system/services/power/ is removed.
This completes library/protocol/: every driver<->service wire contract lives
there and is imported by module name, no protocol is re-exported through
runtime, and the alias chaos (dp/sp, mixed protocol/<x>_protocol) is resolved.
virtio-gpu-protocol stays a driver-private relative import (a hardware command
set, not a driver<->service seam — like virtio-pci.zig beside it).
zig build + test green; power-button, orderly-shutdown pass.
display-protocol -> library/protocol/display/, scanout-protocol ->
library/protocol/scanout/. Consumers import both directly, killing the cryptic
dp/sp aliases in virtio-gpu (now display_protocol / scanout_protocol) and the
runtime.display_protocol / runtime.scanout_protocol re-exports. runtime.display
(the client) still imports display-protocol by name; scanout has no runtime
client, so its runtime module import is dropped too.
zig build + test green; display-service, virtio-gpu, display-native,
display-reattach pass.
device-manager-protocol -> library/protocol/device-manager/. Its consumers
(pci-bus, usb-xhci-bus, the acpi discovery service, device-manager, device-list,
crash-test, and the not-yet-built intel-integrated display sub-driver) import the
module directly instead of through runtime.device_manager_protocol, which is
deleted. runtime.device_manager (the hello client) already imported the module
by name and is unchanged.
zig build + test green; device-manager, driver-restart, device-list, pci-scan pass.
input-protocol -> library/protocol/input/input-protocol.zig. Its five
consumers (usb-hid keyboard/mouse, ps2 keyboard/mouse, the input service) now
import the module directly and alias it input_protocol, replacing the
runtime.input_protocol re-export (deleted) and the inconsistent local `protocol`
aliases. runtime.input (the client) still imports the module by name.
zig build + test green; input, acpi-ps2, usb-hid pass.
vfs-protocol -> library/protocol/vfs/vfs-protocol.zig. fat, its only consumer,
now imports the module directly (const vfs_protocol = @import("vfs-protocol"))
instead of through runtime.vfs_protocol, and the runtime re-export is deleted.
The runtime's own client (runtime.fs) still imports the module by name.
zig build + test green; vfs, fat-mount pass.
Start the protocol tree: wire protocols move to library/protocol/<name>/,
entry file <name>-protocol.zig, module name unchanged. block and usb-transfer
are pure moves — every consumer already imports them by module name, so only
the b.addModule paths change and the empty system/services/block/ is removed.
block-protocol -> library/protocol/block/block-protocol.zig
usb-transfer-protocol -> library/protocol/usb-transfer/usb-transfer-protocol.zig
zig build + test green.
The USB class-driver transfer client was library/runtime/usb.zig, re-exported
as runtime.usb — which compiled the USB client and usb-transfer-protocol into
every user binary (init, fat, the compositor…), none of which speak USB. It is
bus-family logic, not core runtime.
Move it to its domain home, library/device/usb/usb.zig (module "usb"), alongside
the usb-abi and usb-ids data modules; fix its internal imports to go through the
runtime module; and re-export usb.abi / usb.ids so a class driver reaches the
whole USB domain through one import. runtime.usb and runtime's
usb-transfer-protocol import are removed; the three class drivers
(usb-hid keyboard/mouse, usb-storage) import module "usb" directly.
zig build + test green; usb-hid, usb-storage pass.
New pci logic module (library/device/pci/pci.zig): a device driver's view of
the one PCI function it has claimed — Function.map (config space = resource 0),
vendorId/deviceId/command/status, enableMemoryAndBusMaster, mapBar (BAR decode
+ resource correlation + mmio_map, cached), and a capabilities() iterator. The
generic PCI mechanics every leaf PCI driver used to re-derive inline.
The config-space layout it needs — header offsets, the command MEM|bus-master
bits, the status capabilities-list bit, the capability-pointer mask, and the
BAR bit fields — is named in the pci-class data module (a "Configuration-space
layout" section), so the bus enumerator can share the same constants later.
virtio-gpu is the first consumer: its inline mapBar + walkCapabilities + config
header reads are gone, replaced by pci.Function; only the virtio-specific
cfg_type dispatch (and the virtio common-config cfgRead/cfgWrite, which are NOT
PCI config space) stay in the driver. The generic display driver will use the
same module. pci-bus's enumerator (arbitrary-function probing) is untouched.
zig build + test green; virtio-gpu, display-native, display-reattach, pci-scan pass.
The kernel's only dependency on pci-class and acpi-ids was cosmetic: the
boot-time device-tree dump (DeviceTree.dump) decoded class codes and _HID
strings to human names. That is device decoding — a user-space concern in a
microkernel, and the last thing pinning two userspace taxonomies into the
kernel's compile.
dumpNode now prints raw values (the class tag, the raw _HID string, and the
packed PCI class code as hex); a user-space tool that owns the taxonomies
(the device manager already imports them) can pretty-print when wanted. The
pci-class / acpi-ids imports are dropped from device-model.zig and from the
platform module.
The kernel's sole remaining library/device/ import is now device-abi (pure
data — the device-model types the broker marshals across the syscall
boundary), the one intentional kernel->library crossing.
zig build + test green; smoke, discovery, acpi-parse, acpi-ps2 pass.
First step of the device-code reorganization (plan: group device code by
domain, split each domain into a shareable data module + a logic module).
This moves the pure-data modules — the enums, wire types, and taxonomies
that any layer including the kernel can import cheaply — out of
system/devices/ and into their domain home:
device-abi -> library/device/model/device-abi.zig
pci-class -> library/device/pci/pci-class.zig
usb-abi -> library/device/usb/usb-abi.zig
usb-ids -> library/device/usb/usb-ids.zig
acpi-ids -> library/device/acpi/acpi-ids.zig
aml/ -> library/device/acpi/aml/
Module names are unchanged, so this is a pure file move: only the
b.addModule paths and the host-test file list in build.zig change; no
importer is touched. system/devices/ now holds only the kernel-internal
device model (device-model, platform, acpi, device-tree, power).
The device *logic* (the pci Function helper, the usb transfer client) and
the kernel's cosmetic taxonomy dependency are handled in following commits.
zig build + zig build test green.
Every supervised driver owes the device manager a hello at startup, and
the retry-lookup-call-check for it had been copied into five drivers:
usb.helloManager (misfiled in the USB client) plus hand-rolled twins in
display, virtio-gpu, pci-bus, and usb-xhci-bus.
Extract it once as a runtime client, runtime.device_manager.hello(role,
device_id) ?Handle — returns the manager endpoint (bus drivers keep it to
report children through), null when there is no manager or it refused the
handshake, and logs the outcome itself so each call site is one line.
Also correct two roles while collapsing their calls: virtio-gpu and the
display driver each claim one PCI function and report no children, so they
are Role.device, not Role.bus. The manager ignores role today, so this is
cosmetic, but it matches the protocol's own definition (bus = reports
children via child_added).
Behavior-preserving otherwise: pci-bus and usb-xhci-bus move their hello
logging from raw serial writes to std.log, which the kernel renders with
the same "<path>: " prefix, so driver-restart still matches
"usb-xhci-bus: hello acknowledged". zig build clean; 8 QEMU cases pass
(driver-restart, pci-scan, usb-hid, usb-storage, virtio-gpu,
display-reattach, device-list, device-manager).
A fault in any thread, exit from any thread, or process_kill on any member id
now takes down the entire thread group; only a worker's voluntary thread_exit
stays per-thread. Leader id (tgid-style), dying latch on the address space,
group notification at space destruction, shared-memory mapping references,
per-space DMA/shm arena cursors, and the shm/DMA page-table walks brought
under the big kernel lock. Design + red-team + review in
docs/shared-fate-plan.md. QEMU suite: 100/100.
The adversarial review of the branch confirmed the big one: the shm/DMA
page-table walks and their pmm/heap calls ran outside the big kernel lock —
pre-existing, but fatal once the per-space cursors invited sibling threads to
race them (two concurrent creates could orphan a page table: one thread's
region silently unmapped, the frame leaked — a plausible root for the
long-standing intermittent AP ring-3 fault at the shm base). All three paths
now follow the mmap discipline: allocation, object build, record, and handle
under one lock hold with full rollback; the map itself per-page under brief
holds; dma_free's translate/unmap/free per-page likewise.
Contract edges from the same review: thread_spawn into a dying group returns
-ESRCH (was generic -1); process_kill during the condemned window answers
from the latch's stashed supervisor (0 or -EPERM, was -ESRCH once the leader
slot was reaped); exit derives the group reason from its own argument rather
than the racy exit_code global; a worker's thread_exit no longer overwrites a
concurrent group-kill stamp; checkGroupDead now asserts exactly-one
notification via the drained ring. Full suite: 100/100.
Eight new QEMU cases (thread-fault-group, kill-threaded-group,
kill-via-worker-tid, racing-triggers, exit-group, leader-thread-exit,
thread-exit-solo, shm-mapping-ref) driving seven new thread-test modes; a
shared checkGroupDead asserts the contract everywhere: one notification,
badged with the leader, reason on the leader's record, no member listed,
claims released first.
The shm-mapping-ref case flushed out the per-task DMA/shared-memory arena
cursor bug directly (a sibling's regions mapped over the worker's), so both
cursors moved to the AddressSpaceRef like the mmap/MMIO cursors before them
(threading M7 pattern). Runtime gains Thread.tryExitCurrent for the leader
-EPERM refusal path. Docs updated: threading.md's shared-fate gap is closed,
process-management.md and process-lifecycle.md describe the leader re-key,
plan status = implemented. Full suite: 100/100.
system.img was only mentioned in passing (efi.md, system-requirements.md);
its format, builder, fallback chain, and kernel-side life were spread across
pack-system-image.py, build.zig, efi.zig, initial-ramdisk.zig, and vfs.zig.
New dedicated page covers all of it, cross-linked from every prior mention
and added to the docs index.
Each address space that maps a shared-memory region now holds its own
reference, recorded on the AddressSpaceRef and dropped when the space is
destroyed — so 'last reference' means no handles AND no mappings, and a
region's frames can no longer be freed out from under a sibling thread (or
any other live mapper) when the handle-holding task dies. The group-death
notification still posts after every mapping release. (docs/shared-fate-plan.md M3)
All process deaths (exit from any thread, ring-3 fault, process_kill) now kill
the whole thread group via killGroupLocked: latch the AddressSpaceRef as dying
(refusing new members, closing the thread_spawn escape), stamp every member
(leader carries the group reason — the record the supervisor reads), reap
parked members to fixpoint, condemn running ones. The leader's exit
notification and subscriber broadcast move to the group-death moment — the
last address-space reference drop — via scheduler.group_exit_hook, which
re-stamps the leader's exit record first. Leader thread_exit is refused with
-EPERM. kill_pending is atomic; exit_reason and fault_kill_count writes moved
under the big kernel lock. (docs/shared-fate-plan.md M2)
Every task carries its process leader's id (main task: own id; threads:
copied from the spawner; kernel tasks: 0, never followed). process_kill and
process_signal resolve any member id to the leader and authorize against the
leader's supervisor, making both capabilities per-process. ProcessDescriptor
gains the leader field. No fan-out yet (docs/shared-fate-plan.md M1).
Every doc verified claim-by-claim against the code by parallel audit agents,
then fixed and adversarially re-verified. Two waves of staleness corrected:
the originally audited findings (higher-half boot handoff, kernel VFS
takeover, fault isolation + claim release + driver restart, AML/S5 moving to
ring 3, threading's shipped design, USB+FAT landing) and a second pass of
adjacent claims the verifiers caught (smp.md 'not built yet' intro,
system-requirements' PS/2-only and no-storage claims, halting.md's red-panic
and no-IDT text, testing.md's serial mirroring, router-era vfs-protocol
wording, capsule-first boot loading).
threading.md now documents the shared-fate gap explicitly: the design says a
process dies whole, the kernel today kills only the offending thread.
Also fixes three stale code comments (isr.s exceptionHandler, acpi.zig
sleepValue, build.zig boot-volume) — comments only, no behavior change.
Verified every deferred item in the nine docs with a what's-next section and
marked what has since landed (reaper, per-process CR3, higher-half kernel,
kernel heap, contiguous frame alloc, RSDP capture, cap-passing, driver restart
with backoff, PS/2 keyboard) while keeping the genuinely open items. Also
corrects interrupts.md's claim that the keyboard skipped the IO-APIC, and
updates scheduler.zig/heap.zig comments that predated the reaper and the big
kernel lock.
Rename the file to match current naming conventions and update all
cross-references throughout the documentation. Update the content to
reflect the current state of the codebase:
- Module is now called "architecture", not "arch"
- Directory is system/kernel/architecture/, not system/kernel/arch/
- Generic kernel file is kernel.zig, not main.zig
- Updated file listing for x86_64 architecture module (added smp.zig,
per-cpu.zig, ioapic.zig, trampoline.s)
- Updated function list in cpu.zig to include enterUser/userExit and
address-space management
- Clarified that _start lives in architecture-specific isr.s
- Expanded architecture-specific vs generic comparison table with
actual current modules
Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
Directory scans and FAT-chain walks re-read the same sectors constantly:
resolving many paths under one directory (a logging burst opening dozens
of files under /var/log/<stamp>/) re-read that directory's sectors and the
FAT from the device every time. Add a 16-line write-through cache under the
single-sector blockRead/blockWrite path, keyed by filesystem-relative LBA
with round-robin eviction, so repeated metadata reads come from RAM instead
of a USB round trip each.
Disciplines that keep it safe:
- Write-through: every write reaches the device immediately and refreshes
the cache, so it never holds dirty-only data — the crash-safe
data->FAT->directory write order and the flush-on-close are unchanged.
- Bulk file data (the B5a multi-sector run path) bypasses the cache and a
run write invalidates any overlapping cached sector, so metadata that
shares a range can never go stale.
- Cluster-zeroing writes uncached (write-once bulk that would only evict
live metadata), invalidating any stale copy.
A new engine test proves a repeated resolve does zero device reads and that
a write is coherent both in-cache and against a cold-mounted filesystem
(it really reached the device).
Full QEMU suite green (the one intermittent `logger` miss is the documented
pre-existing AP ring-3 fault: 16/16 logger reruns pass on this change and
every other storage case is green; the fat engine is single-threaded and
the cache is bounded global state, so it cannot itself fault intermittently).
The FAT engine read and wrote one sector per device command — one SCSI
READ(10)/WRITE(10) over USB Bulk-Only Transport per 512 bytes, so every
file read, log write, and cluster fill paid a full USB round trip per
sector. The lower stack (runtime.block, the block protocol, usb-storage's
read10/write10 + count*block_size data stage) already carried a
multi-sector count; only the engine's BlockDevice interface and IpcBlock
were single-sector.
Widen BlockDevice to move a run of `count` contiguous sectors per call
(readBlock/writeBlock kept as count=1 wrappers, so metadata call sites —
FAT sectors, directory entries — are untouched). readFile and writeFile
now coalesce the aligned full-sector middle of a transfer into one command
(capped at the cluster boundary and the 4 KiB bounce = 8 sectors), reading
straight into / writing straight from the caller's buffer with no staging
copy. Full-sector writes skip the read-modify-write entirely, since they
overwrite the whole sector. Partial head/tail sectors keep the per-sector
RMW path.
IpcBlock passes count through to the block driver and sizes its bounce from
engine.max_transfer_sectors (already 4 KiB — no new allocation). A new
spc=8 engine test proves runs coalesce (a 21-sector overwrite drops from
>=21 writes to <=5) and that reads/writes round-trip byte-identical,
including an unaligned offset spanning a cluster boundary.
Full QEMU suite 92/92.
USB hub support, root-caused and validated on the user's real machine:
a Keychron keyboard and ROG mouse now enumerate through a Genesys
compound USB3 hub (its USB2 companion + transaction translators) and
type on danos.
Fixes found by reading logs off the stick, each invisible to QEMU:
- SuperSpeed hubs have change bits a USB2 hub lacks; not clearing them
spun the driver. Clear them (gated on speed) + a per-tick service cap.
- The boot scan runs ~3 ms after the controller reset, too early for a
USB2 connection to debounce; the SuperSpeed devices train instantly
and hid the problem. Poll the root ports on the tick (edge-triggered).
- Full-speed devices failed Address Device with a USB Transaction Error:
USB 2.0 requires a 10 ms reset-recovery interval before SET_ADDRESS.
Wait it out, and retry Address Device on a transaction error.
Plus richer logs: readable PORTSC decode, USB link-state and speed
names, device string descriptors (maker/product), and a readable name
for every class/subclass/protocol enum in usb-ids. Full suite 92/92.
Open follow-up: 'port 11 enumeration failed' — a third device that did
not come up; to be investigated separately.
Every enum in usb-ids now has a name function, so any code (logs, tools)
can print the readable value instead of a raw byte: hub.protocolName,
hid.subclassName/protocolName, mass_storage.subclassName/protocolName,
communications.subclassName, wireless_controller.subclassName/
protocolName, miscellaneous.subclassName/protocolName,
application_specific.subclassName (alongside the existing className,
speedName, linkStateName).
interfaceName is now comprehensive across classes — it decodes the
well-known triples a log shows: 'HID boot keyboard', 'Mass Storage
(Bulk-Only)', 'Hub (SuperSpeed)', 'Bluetooth' (E0/01/01), etc. So the
bus log reads e.g.
interface 0: Mass Storage (Bulk-Only) (8/6/80) registered as device 30
interface 0: HID boot keyboard (3/1/1) registered as device 33
Host-tested with usb-ids (the name decodings are pinned). Vendor-ID
naming deliberately left out (needs a data table); this is pure standard
class-code decoding.
The compound-hub investigation is resolved (Keychron keyboard + ROG
mouse enumerate through the Genesys USB2 companion hub and type on real
hardware). Turn the debugging spam back down for main: the full 22-port
PORTSC dump runs only when a scan finds NOTHING (a 'why is this empty'
aid), not every boot; a downstream hub port logs only when a device
actually appears or leaves, not for every empty seed-sweep port. The
readable device names, class names, and port-change events stay.
Real-hardware root-cause, from the now-readable log: the tick-poll fix
DID catch the user's full-speed devices (USB2 root ports 3, 9, 11
'device appeared — Full-speed'), but every one failed 'Address Device
completion code 4' = USB Transaction Error. Cause: danos addressed the
device immediately after the port reset, but USB 2.0 (spec 7.1.7.5)
requires a reset-recovery interval (TRSTRCY, 10 ms) before a device
answers SET_ADDRESS. QEMU tolerates the omission; real full-speed
devices do not.
setupDevice now waits 10 ms after a port reset before addressing, and
addressDeviceCommand retries up to 3 times on a transaction error,
re-resetting a root-port device between attempts (xHCI 4.6.5 recovery).
QEMU USB cases still green. Real-hardware confirmation pending — this is
the specific fix for the user's keyboard/mouse failing to address.
Make the USB diagnostic logs scannable by eye:
- usb-ids gains speedName + linkStateName (USB3 PORTSC link states: U0,
RxDetect, Polling, ...), host-tested with usb-ids.
- The PORTSC dump decodes the register instead of printing hex flags:
PORTSC[3] 0x00021203: connected, enabled, link=U0, power=on, SuperSpeed
PORTSC[5] 0x00020ee1: connected, disabled, link=Polling, power=on, High-speed
(the raw word stays for reference). A USB2 device reads connected+
disabled+Polling until reset — so the user's next log shows at a glance
whether the companion port ever reaches that state.
- The library reads STRING descriptors (readString, UTF-16LE -> ASCII,
English langid), and the device line now names the maker + product:
port 5 device: Hub "Genesys Logic USB3.0 Hub" (0x05e3:0x0626), 1 interface(s)
instead of a bare vendor/product id pair.
Full USB case set green (hub regexes follow the new 'device: <class>
"<maker> <product>"' format). Branch diagnostics for the SuperSpeed
compound-hub investigation.
The logs read 'class 9/0/0' where they could say 'Hub'. usb-ids gains
className (a device/interface class byte -> 'Hub', 'HID', 'Mass Storage',
...) and interfaceName (a HID boot interface -> 'HID boot keyboard' /
'HID boot mouse'), both host-tested with usb-ids. The bus driver's
enumerate + register lines now read, e.g.:
port 21 device: Hub vendor 0x05e3 product 0x0626, 1 interface(s)
port 21 interface 0: Hub (9/0/0) registered as device 47
port 5 interface 0: HID boot keyboard (3/1/1) registered as device 32
so a real-hardware log is scannable by eye. Full USB case set green
(hub regexes follow the new 'device: <name>' format).
Real-hardware root-cause: the user's keyboard works in the firmware boot
menu but dies under danos. The port dump shows why — danos scans the
root ports ~3 ms after the controller reset, but a USB2 connection needs
~100 ms to debounce, so the boot scan sees the USB2 companion hub's port
empty (all USB2 ports ccs=0), while the SuperSpeed devices (hub, storage)
train instantly and DO show up. danos then relied on a Port Status
Change EVENT to catch the late USB2 connection, which does not fire
reliably on this hardware.
The tick now polls every root port and reconciles on the empty->connected
EDGE (previous-state tracked per port, seeded from the boot scan so
already-up ports never re-fire), bringing up a device that appears after
the scan without depending on the event. Edge-triggered so a port that
fails to enumerate is not retried every 8 ms. Branch-only until the
keyboard is confirmed on real hardware; the diagnostic dumps stay for
the next boot.
The USB2 companion hub carrying the user's full-speed keyboard never
appears — only the SuperSpeed hub (port 19) and SS storage (port 21)
connect. To find where the USB2 root ports are and whether the companion
is presenting on one, walk the xECP Supported Protocol capabilities
(logging each USB 2.0 / 3.0 root-port range) and dump every port's raw
PORTSC unconditionally (ccs/ped/pls/pp/speed). QEMU confirms the dump
(USB2 ports 5-8, USB3 ports 1-4). Branch-only diagnostic.
Branch-only debugging for the real SuperSpeed compound hub: the spin fix
(27f87cb) stopped the hang — the SS hub's 4 SuperSpeed ports now enumerate
(all empty, correct: the full-speed keyboard isn't a SuperSpeed device) —
but the USB2 COMPANION hub, where the keyboard actually lives, never
appears. Only root ports 19 (SS hub) and 21 (SS storage) connect.
Dump every root port's raw PORTSC at scan (connect/enable/link-state/
speed) and log every root port-change event, so the next boot shows
whether the companion is connected on a USB2 port we misread, connects
late as a port-change event, or is simply absent. Diagnostic logging —
to be removed once the companion path works.
Real-hardware finding: a SuperSpeed hub (the user's Genesys, 4 SS
downstream ports) HUNG the bus driver at boot — it stopped logging with
no fault, and the hub's port power dropped. Cause: a SuperSpeed hub has
change bits a USB2 hub lacks (link-state, BH-reset), and the B4 servicing
— written and tested against QEMU's USB2 hub — never cleared them, so
the hub's status-change endpoint re-reported the same port forever and
the driver spun servicing it, never reaching the USB2 companion hub
where the full-speed keyboard actually lives.
hubPortStatusAck now clears the SuperSpeed-only change features too
(gated on hub speed; a USB2 hub is unaffected), and the tick services a
bounded batch of hub changes (32) before yielding — so even if a hub's
change bits misbehave, the driver cannot spin the machine. A per-port
status log line surfaces exactly what a hub reports, so the next real
boot shows the SS hub's port states and whether the USB2 companion
enumerates. QEMU usb-hub cases still green (the SS clears are gated off
for QEMU's USB2 hub).
There was no way to confirm a keyboard actually registers keys on real
hardware (enumeration binding the driver only proves the device came
up). The keyboard driver now echoes each decoded printable character
(and newline) to its log: type a known phrase and read it back from
usb-hid-keyboard.log, or watch it appear live on screen in a -Ddiagnose
boot (where the kernel console is a log sink). It exercises the whole
path — HID report -> diff -> layout -> character — not just enumeration,
and works identically for a keyboard behind a hub.
A usb-key-echo QEMU case injects a phrase via QMP send-key and asserts
it echoes (stable across repeated runs). Full suite 92/92.
Completes hub support (docs/usb-hub.md). On the bus tick, a downstream
hub-port change now dispatches: a connect enumerates the new device
(B4b), a disconnect tears the old one down — recursively, since a hub
that leaves takes its whole subtree with it (children first), reporting
each interface ChildRemoved and Disable-Slotting the device. Route
strings compose across tiers, so a device two hubs deep enumerates with
a two-tier route.
QEMU's hub — unlike root-port hot-plug — DOES raise downstream
status-change events, so both paths are harness-tested: usb-hub (a
keyboard behind a hub binds usb-hid-keyboard), usb-hub-nested (a
keyboard two hubs deep), usb-hub-unplug (device_del behind the hub tears
it down). Full suite 91/91.
Real-hardware validation of the user's SuperSpeed Genesys hub with
full-speed devices on its USB2 companion is flagged for the user (QEMU's
USB2 hub does not model the compound USB3 hub).
The core of hub support (docs/usb-hub.md): a device on a hub's
downstream port now reaches its class driver exactly like one on a root
port. The hub's interrupt status-change endpoint is armed with an
in-process subscription — completions set the hub's pending-port mask
instead of queuing a class-driver report — and setupHub seeds every
downstream port pending so a STATIC topology (a device present at
power-on) enumerates without waiting on the initial interrupt edge.
On the bus tick, each pending hub port is serviced: GET_STATUS + clear
the change bits, and on a connect reset the port, read the speed, then
enable a slot and Address Device with the composed route string
((parent_route<<4)|port), the inherited root port, and the parent hub's
slot/port as the TRANSACTION TRANSLATOR — so the controller routes a
full/low-speed device's split transactions through the hub's TT. The
device then enumerates and registers its interfaces through the normal
path (a compact topology-unique port key keeps the id tag within its
8-byte cap), recursing setupHub if it is itself a hub.
Verified in QEMU (a keyboard behind a USB2 hub on a second controller):
'hub slot 1 port 1 device vendor 0x0627 ... usb-hid-keyboard: ok
(device 35)'. Full suite 89/89. The user's SuperSpeed Genesys hub +
full-speed keyboard/mouse on its USB2 companion is the real-hardware
target, flagged separately.
First slice of hub support (docs/usb-hub.md), handled IN the xhci-bus
because a device behind a hub is reached by the CONTROLLER via a route
string in its slot context — topology only exists inside the driver
that owns the controller. When the scan enumerates a class-9 device it
now calls setupHub: read the hub descriptor for the downstream port
count and TT arrangement, tell the controller the slot is a hub
(Configure Endpoint with the slot add-flag sets the Hub bit, Number of
Ports, and MTT/TT-Think-Time per xHCI 4.6.6), SET_HUB_DEPTH for a
SuperSpeed hub so it can compose route strings, and SET_FEATURE
PORT_POWER every downstream port.
The Device gains topology fields (route string, root port, parent hub
slot/port for the TT) and buildAddressInputContext now fills them, so
the Address Device path is ready for downstream devices — those are
enumerated in B4b. A root-port device gets route 0 and its own port as
the chain root, unchanged behavior.
Verified in QEMU with a hub on a second controller and a device behind
it (a usb-hub QEMU case, since the boot controller's auto-assigned
devices collide on the low ports): 'hub slot 1: 8 downstream ports
powered (USB2 single-TT)'. Full suite 89/89. The user's SuperSpeed
Genesys hub is the real-hardware target, flagged separately (QEMU's
USB2 hub doesn't model the compound USB3 hub).
Regression from the B3 MPS0 work, caught on real hardware: a SuperSpeed
hub (and the SuperSpeed boot stick) failed to enumerate. bMaxPacketSize0
(device descriptor byte 7) is a LITERAL size for USB 2.0 and below
(8/16/32/64) but an EXPONENT for SuperSpeed (9 = 2^9 = 512). The refresh
read the exponent 9 as a size and issued Evaluate Context to set EP0 to
9 bytes, corrupting the control endpoint so every following transfer
failed. SuperSpeed's EP0 is fixed at 512 and needs no correction, so
the refresh is now skipped for speed >= 4; only full/low/high speed,
where the field is a literal that can differ from the speed default,
still run it. QEMU tolerated the wrong MPS0 — real silicon does not
(the class of bug the harness can't reach, flagged real-HW-pending).
This likely also explains intermittent no-storage/no-logs on a normal
boot: the boot stick is SuperSpeed and hit the same corruption. Full
suite green (orderly-shutdown's lone failure was its known QMP-timing
flake — three clean re-runs).
B3 — the runtime lifecycle a hot-pluggable bus needs, plus two init
fixes that runtime device arrival depends on:
- pump() now handles PORT STATUS CHANGE events (silently dropped
before): it queues the port, and the bus driver brings the port up
(a device arrived) or tears it down (a device left) on its tick —
reporting each interface ChildRemoved to the device manager, which
prunes the node, notifies watchers, and lets the class driver's world
end honestly, then Disable Slot frees the controller-side state.
- ALL root-hub ports are powered at init, not just those with a
boot-time device: an unpowered port (PP=0) cannot signal a later
connect, so a hot-plug would never be seen.
- the interrupter is enabled (IMAN.IE + USBCMD.INTE) while the ring
stays polled — some controllers only WRITE runtime events to the
ring when the interrupter is enabled.
Real-hardware validation is flagged for the user: QEMU's qemu-xhci does
not raise a runtime port-change event to a polling driver on device_add,
so the end-to-end hot-plug path can't be exercised in the harness (the
port-change handling itself IS proven — a late boot device's PSCE is
caught and acked). The harness gained qmp_sequence (multi-step QMP
injection with arguments) for when a drivable case exists. Full suite
88/88; the working USB path (enumeration, HID, storage) is unregressed
by the port-power and interrupter changes.
The guest mutates its boot volume (fat tests create files, the logger
writes /var/log) and QEMU is hard-killed after a match, so booting the
build artifact in place let one run's leftovers fail the next — a stale
TESTDIR tripping the mkdir-duplicate refusal was the lone 87/88 failure
in an otherwise green suite — and dirtied the build cache's own output.
Each case now boots a fresh copy in the work directory.
Two real-hardware correctness fixes from the M20 list, both invisible
to QEMU's forgiving controller:
refreshMaxPacketSize0 existed only as a comment. The EP0 context kept
the SPEED-DEFAULT max packet size (full-speed: 8) even when the device
declares 16/32/64 — real controllers fault the very first full
descriptor read on the mismatch, which is the standing suspect for
full-speed mice dying on the user's PC. Enumeration now probes the
device descriptor's first 8 bytes (deliverable at any legal MPS0),
and issues Evaluate Context to correct EP0 before any longer transfer,
naming the failure and codes if the controller refuses.
And a USB2 port's PORTSC speed field is only meaningful once the port
reset ENABLES the port: the speed (and the MPS0 default derived from
it) is now sampled after the reset instead of trusting the connect-time
read.
B2 — the 1-in-3 boot-time READ CAPACITY failure, root-caused: the xHCI
library's awaitTransfer claimed ANY unclaimed transfer event as its own
completion. An interrupt-endpoint event whose TRB pointer no longer
matched the armed subscription (an error or stale completion from the
keyboard/mouse polling concurrently with storage bring-up) fell through
and was misread as the bulk transfer's completion — desynchronizing the
mass-storage bulk protocol in controller state that SURVIVED driver
restarts, so every retry failed too. Awaited transfers now match the
event's slot id and endpoint DCI; foreign events are dropped and named.
Twelve consecutive runs of the previously-flaky cases pass; the full
suite is green with none of its old intermittents.
B1 — and when storage does fail transiently, the system now heals
instead of giving up forever: a nonzero exit maps to ExitReason.aborted
(a deliberate FAILURE exit — supervisors restart those with backoff,
unlike a clean .exited), usb-storage exits nonzero when a PRESENT
device fails bring-up, and the fat service no longer blocks its harness
polling for a block device and then dies — it serves immediately
(requests fail politely), retries on a 500 ms timer, and mounts
whenever storage appears, including after a driver restart.
(An earlier append landed on a line missing its newline, mangling
'.github/' and silently un-ignoring var/ — which let a stray add sweep
pulled logs into the tree. Repaired, and the logs untracked again.)
Its only content was the redundant announce line — the useful shutdown
marker was written AFTER the final drain, so it reached serial and the
ring but never a file, and a truncated boot could only be inferred from
what was missing. The marker now enters the ring BEFORE the drain, so
the drain carries it into logger.log: a directory whose logger.log ends
with 'shutting down; final flush' is complete through shutdown; one
without it was cut early. The sequence-count epilogue stays serial-only,
after the drain, by design.
First real per-process logs off the stick (the logging track paying for
itself): kernel.log showed 16-core bring-up costing 47 s — per-core gaps
of 2-21 s — on a machine whose clocksource is the TSC, so every AP runs
the pairwise warp check. QEMU always picks HPET, so the harness never
executed this path at all.
The check was bounded by ITERATIONS: 1<<20 warp ticks, each a locked
read-modify-write on a cacheline two cores fight over — microseconds
under real contention, not the nanosecond the '~1 ms' comment assumed —
and the 1<<32-PAUSE rendezvous 'bound' is ~2 minutes on modern Intel
(PAUSE ~140 cycles). Both are now bounded by TIME measured on the TSC
itself: ~5 ms of pairwise hammering per core (Linux's check_tsc_warp
budget — ample to catch a lagging TSC) and a ~100 ms rendezvous window.
Real-PC diagnose boot (photo + OCR): the boot stick connects at
SuperSpeed on port 21 and 'device setup failed' lands in the SAME
millisecond — an instant failure, not a timeout. setupDevice reset
every port unconditionally; that is required to enable USB2 ports, but
a SuperSpeed port that trained its link is ALREADY enabled (xHCI
advances USB3 ports to Enabled, no reset — spec 4.3), and driving a hot
reset into the live link drops PED mid-reset on real silicon. QEMU
tolerates the spurious reset, which is why the harness never saw it.
An enabled speed>=4 port now skips the reset (a not-yet-enabled SS link
still gets one). Every setup step names its failure — port reset with
the PORTSC value, Enable Slot, device-slot exhaustion, Address Device
with its completion code — so the on-screen transcript of the next
failure identifies the exact xHCI command instead of one blanket line.
block.open's give-up window drops 60 s -> 30 s (the slowest observed
healthy chain completed at ~24 s); a machine whose stick failed setup
should not sit a further minute pretending otherwise.
The scroll path copied every pixel row up by one glyph height, READING
video memory — and VRAM reads are uncached-slow on real hardware.
Measured on the 16-core PC: ~90 seconds to bring the cores online,
almost entirely boot-transcript lines each paying a whole-screen scroll
copy. (QEMU never shows this: its 'VRAM' is host RAM.)
When the screen fills, the console now clears and restarts at the top —
writes only, once per screenful. The transcript reads the same as it
streams; only the scrollback illusion is gone, which a boot console
never needed.
Daniel Samson
