Daniel Samson
83881641ca
A user-space process can now touch real hardware directly, capability-gated by the device tree — the microkernel driver model. - src/kernel/devsvc.zig: flattens the discovered device tree into an id-indexed snapshot + a claim table at boot (devsvc.init from main.zig). - Syscalls 11-13: dev_enumerate (snapshot the table), dev_claim (take exclusive ownership), mmio_map (map a claimed device's MMIO window into the caller's AS and return the register base). The claim is the capability: mmio_map refuses any device the caller doesn't own. - paging.mapUserDeviceInto: maps device MMIO strong-uncacheable (PCD|PWT) and marks each leaf with a device_grant PTE bit; freeSubtree skips pmm.free on those leaves, so tearing down a driver never returns MMIO frames to the RAM pool (the teardown hazard). MMIO grants live in a distinct arena, PML4[226] (Task.dev_map_next), so device pages widen no kernel mapping. - lib/dev.zig: user enumerate/claim/mmioMap wrappers; shared DeviceDesc/ResDesc in danos (root.zig). sbin/hpetd.zig: finds the HPET, claims it, maps its registers, enables the counter (an MMIO write) and reads it (0xF0) — proving read+write passthrough to real hardware. - Tests: `hpet` (driver reads the counter advancing from ring 3) and `iopass` (device-granted frame survives address-space teardown). Suite 33/33. irq_bind/irq_ack (IRQ-as-message) are stubbed (-1) pending; notifyFromIsr (M7) is the hook they'll use.
33 lines
1.2 KiB
Zig
33 lines
1.2 KiB
Zig
//! User-space device access: enumerate the kernel's device table, claim a
|
|
//! device, and map its MMIO. A driver uses these to find and take ownership of
|
|
//! its hardware; the claim is the capability the kernel checks before mapping.
|
|
|
|
const danos = @import("danos");
|
|
const sc = @import("syscall.zig");
|
|
|
|
pub const DeviceDesc = danos.DeviceDesc;
|
|
pub const ResDesc = danos.ResDesc;
|
|
pub const DeviceClass = danos.DeviceClass;
|
|
pub const ResourceKind = danos.ResourceKind;
|
|
|
|
inline fn failed(r: usize) bool {
|
|
return r > ~@as(usize, 0) - 4095;
|
|
}
|
|
|
|
/// Copy up to `buf.len` device descriptors into `buf`; returns the total count.
|
|
pub fn enumerate(buf: []DeviceDesc) usize {
|
|
return sc.syscall2(.dev_enumerate, @intFromPtr(buf.ptr), buf.len);
|
|
}
|
|
|
|
/// Take exclusive ownership of device `id`. Returns false if taken or invalid.
|
|
pub fn claim(id: u64) bool {
|
|
return !failed(sc.syscall1(.dev_claim, id));
|
|
}
|
|
|
|
/// Map resource `res_idx` (which must be an MMIO window) of claimed device
|
|
/// `dev_id` into this address space; returns the register base virtual address.
|
|
pub fn mmioMap(dev_id: u64, res_idx: u64) ?usize {
|
|
const r = sc.syscall2(.mmio_map, dev_id, res_idx);
|
|
return if (failed(r)) null else r;
|
|
}
|