Devices can now arrive and leave after boot. A "usbhotplug" kernel thread
handles root-port changes, which it is told about by Port Status Change
events and also checks for every quarter second. It also handles changes
behind hubs, which each hub reports on its status-change endpoint. An
unplugged device has its endpoints closed and any transfer in flight
failed. Then its drivers' disconnect hooks run, the slot is disabled and
its memory is freed. Everything behind a hub that goes goes with it. This
needed the interrupt handler to file command and endpoint-0 completions
for their waiters, so that enumeration can run while keyboards interrupt.
On real hardware: the controller is taken from the firmware through USB
Legacy Support before reset, with SMIs off. On Intel 7/8/9 series parts
the ports are switched over from EHCI, which is where firmware leaves
them.
Every interface of a device is offered to the class drivers, not just
the first, so a receiver's mouse on interface 1 gets a driver. Configure
Endpoint now copies the slot context from the controller. Before, it
rebuilt it and lost the route string and TT fields of devices behind
hubs.
HID: pointers are read in report protocol from their report descriptor.
That covers buttons, X/Y and wheel, relative or absolute, and report IDs.
Boot protocol is kept as the fallback for mice and for keyboards.
Non-pointer HID interfaces are declined rather than treated as tablets.
USB keyboards get software key repeat. Mass storage handles up to four
sticks, each unregistered from the block layer when it is pulled out,
along with its cached blocks.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HH7xukt4aaiGj1nQEAoQf1
Groundwork for usb-tablet, which is the fix for the guest cursor and the
host's never being in the same place: a PS/2 mouse reports how far it
moved, two pointers accumulating deltas independently drift apart, and no
amount of care in the compositor can make them agree. An absolute device
reports where it is, so they coincide by construction.
- the HID driver no longer matches the boot subclass only. usb-tablet
declares subclass 0 and was refused at the door; hid_probe decides
what an interface actually is, and still declines what it cannot make
sense of.
- a non-boot HID interface is taken to be an absolute pointer and is
not asked for boot protocol, which it does not have -- that request
failing is what stopped it binding.
- tablet_report decodes the fixed 6-byte layout (buttons, 16-bit X,
16-bit Y, wheel) and scales the logical range to pixels there,
because it is the only place that knows the range.
- input_mouse_abs reports EV_ABS/ABS_X/ABS_Y so a reader can tell an
absolute position from a delta, and mouse_set_abs places the pointer
rather than nudging it.
- Schcom treats EV_ABS as authoritative and EV_REL as a nudge.
The device binds and identifies correctly: "usb-hid: tablet (absolute) on
slot 1, endpoint 0x81 every 4 ms".
It is NOT finished, and QEMU_INPUT is empty by default because of it. No
reports have yet been observed arriving on the tablet's interrupt
endpoint, so making it the default pointer would trade a cursor that
drifts for one that does not move at all. Opt in with
make qemu QEMU_INPUT='-device qemu-xhci,id=xhci -device usb-tablet,bus=xhci.0'
Next step is to find out why nothing arrives: whether the first transfer
is queued but never completes, whether a completion needs re-arming for
this endpoint, or whether QEMU is not routing motion to the tablet at all
(`info mice`).
bootcheck 108 [ok], schcom-test passes.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
An x86-64 operating system built from xv6, now largely rewritten: SMP,
a copy-on-write root filesystem (SchFS), PCI/USB/virtio drivers, a TTF
rasteriser, and a Linux-numbered syscall ABI.
No history before this point -- the tree was never under version control.
This commit exists so the rename that follows has something to undo to.
