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Rename the shared contract module danos -> system; QEMU logs to /var/log/system

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The shared kernel<->user ABI contract (BootInformation, the SystemCall numbers,
DeviceDescriptor, page_size, ...) is now the `system` module at
system/system.zig, following the convention that a directory's root file takes
the directory's name.

One overlap to note: the runtime's syscall wrappers are already `runtime.system`,
so the single file that uses both the contract and those wrappers
(library/runtime/heap.zig) aliases the wrappers locally as `system_calls`. The
two are distinct (top-level `system` vs `runtime.system`); everywhere else the
contract is just `system`.

Also: the QEMU run's serial capture now lands in the FHS log location,
zig-out/var/log/system/serial0-<timestamp>.log — a stand-in for the kernel's own
logging system, which will eventually write there itself.

Suite 35/35 plus host tests green.
This commit is contained in:
Daniel Samson
2026-07-10 14:09:38 +01:00
parent 3d1de37d0e
commit d19a0ae38d
38 changed files with 202 additions and 198 deletions
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docs/efi.md
+7 -7
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@@ -86,9 +86,9 @@ All of this *must* happen now, because after exit there's no GOP to ask. (See
- Use the **LoadedImage** protocol to discover which device we booted from, then
**SimpleFileSystem** to open that volume.
- Open the file named `danos`, seek to the end to learn its size, rewind, and read
the whole ELF into a firmware-allocated pool buffer. (`read` may return short, so
we loop.)
- Open the kernel ELF at its FHS path (`system\kernel`), seek to the end to learn its
size, rewind, and read the whole ELF into a firmware-allocated pool buffer. (`read`
may return short, so we loop.)
- Parse the ELF: validate the `\x7fELF` magic and the `x86_64` machine type, then
walk the program headers. For every `PT_LOAD` segment we:
- reserve the exact physical pages it's linked at (`p_paddr`) via
@@ -124,7 +124,7 @@ entirely ours.
### 4. Jump to the kernel
```zig
const kernel: *const fn (*const BootInfo) callconv(danos.kernel_abi) noreturn =
const kernel: *const fn (*const BootInfo) callconv(system.kernel_abi) noreturn =
@ptrFromInt(entry);
kernel(&boot_info);
```
@@ -142,17 +142,17 @@ kernel is freestanding and uses the **SysV AMD64** convention (first argument in
read garbage.
So both sides pin the convention explicitly to SysV via the shared
`danos.kernel_abi` (defined in `system/danos.zig`). The loader's function-pointer type
`system.kernel_abi` (defined in `system/system.zig`). The loader's function-pointer type
and the kernel's `_start` both reference it, so the pointer lands in the register
the kernel expects. This is the whole reason `kernel_abi` lives in the shared
`danos` module: it's a contract both binaries must agree on. See
`system` module: it's a contract both binaries must agree on. See
[sysv.md](sysv.md) for what "SysV" means and where else it shows up.
## The handoff contract
The loader and kernel are two *separate* binaries built for two different targets,
so everything they exchange must have an identically-defined memory layout. That's
what `system/danos.zig` provides — imported by both as the `danos` module:
what `system/system.zig` provides — imported by both as the `system` module:
- `BootInfo` — the top-level struct passed to the kernel (currently just the
framebuffer; this is where future handoff data like the memory map will go).