USB2/1.1 (EHCI/UHCI) drivers + real-hardware bring-up hardening

- Add polled EHCI (USB2) and UHCI (USB1.1) host-controller drivers with
  HID boot mouse support, wired into cursor polling and the 'usb' shell cmd
- Add USB Legacy ownership handoff (claim_usb_legacy) plus config_write_byte
- Harden boot: verify the PIT/timer ticks before shell entry, EOI stray
  interrupts in the LAPIC to stop interrupt storms, bound PS/2 controller
  waits, and INTx-disable AHCI (polled driver)
- Add boot stage markers, klog screen echo, and QR lock; scheduler
  mark_shell_running; NO_USB stopgap to keep BIOS USB-Legacy input alive
- alloc_pages_above for DMA buffers that must avoid low conventional memory
- Expand DEBUG_NOTES with EHCI/QEMU bring-up findings

1 files changed, 5 insertions, 1 deletions

diff --git a/rsnix/src/cursor.rs b/rsnix/src/cursor.rs
index d9d97bc..31b919e 100644
--- a/rsnix/src/cursor.rs
+++ b/rsnix/src/cursor.rs
@@ -50,7 +50,11 @@ fn forward_target() -> Option<usize> {
 
 fn task_main() {
     loop {
-        while let Some(ev) = crate::usb::poll_mouse().or_else(crate::ps2::try_poll_mouse) {
+        while let Some(ev) = crate::usb::poll_mouse()
+            .or_else(crate::ehci::poll_mouse)
+            .or_else(crate::uhci::poll_mouse)
+            .or_else(crate::ps2::try_poll_mouse)
+        {
             crate::gop::cursor_move(ev.dx, ev.dy);
             crate::gop::cursor_set_buttons(btn_bits(&ev));
             if let Some(id) = forward_target()