From be868a43185826b02bf6d091019bb779678525bb Mon Sep 17 00:00:00 2001
From: salmonik <salmonik@tuta.io>
Date: Mon, 17 Aug 2026 14:53:52 +0200
Subject: 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
---
 rsdos/src/main.rs | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 59 insertions(+), 3 deletions(-)

(limited to 'rsdos')

diff --git a/rsdos/src/main.rs b/rsdos/src/main.rs
index 27dab06..0e159e6 100644
--- a/rsdos/src/main.rs
+++ b/rsdos/src/main.rs
@@ -247,6 +247,25 @@ pub unsafe extern "efiapi" fn efi_main(image_handle: Handle, system_table: *mut
     }
     rsnix::interrupts::init();
     rsnix::serial_println!("intr: IDT loaded, PIC remapped, timer ~100 Hz");
+    // Prove the timer actually ticks before handing the machine to the
+    // scheduler: if the PIC/APIC route is broken on real hardware, the
+    // first `hlt` (shell input, idle) never wakes and the system silently
+    // freezes.  Spin briefly with interrupts on and require uptime to
+    // advance; a dead timer becomes a visible panic instead.
+    let t0 = rsnix::interrupts::uptime_ms();
+    let mut timer_ok = false;
+    for _ in 0..2_000_000 {
+        core::hint::spin_loop();
+        if rsnix::interrupts::uptime_ms() != t0 {
+            timer_ok = true;
+            break;
+        }
+    }
+    if timer_ok {
+        rsnix::serial_println!("intr: timer verified (uptime advances)");
+    } else {
+        panic!("timer: no PIT tick within 2M spins — interrupt routing broken");
+    }
     rsnix::gop::boot_marker("rsnix: serial+ps2+gdt+intr ok");
 
     dump_memory_summary();
@@ -347,13 +366,50 @@ pub unsafe extern "efiapi" fn efi_main(image_handle: Handle, system_table: *mut
 
     rsnix::serial_println!("boot: entering shell");
     rsnix::gop::boot_marker("rsnix: boot done — shell");
-    // USB (xHCI) mouse is polled; fall back to PS/2 if no USB mouse.
-    rsnix::usb::init();
-    if rsnix::ps2::mouse_present() || rsnix::usb::controller_up() {
+    // USB (xHCI) / EHCI mouse is polled; fall back to PS/2 if no USB mouse.
+    // Each stage draws its own marker: a real-hardware freeze leaves the
+    // last completed stage on the screen, so the hang point is identifiable
+    // without a serial console.
+    // STOPGAP: skip ALL USB host-controller init so the BIOS USB-Legacy SMI
+    // keeps emulating the keyboard/mouse on the 8042 (PS/2).  Resetting the
+    // EHCI without a completed USBLEGSUP ownership handshake killed the
+    // firmware's legacy emulation, leaving the OptiPlex 7010 with zero input.
+    // While NO_USB is set, USB input is served entirely by the BIOS (IRQ1/
+    // IRQ12 + our PS/2 driver) and no EHCI/xHCI/UHCI register is touched.
+    const NO_USB: bool = false;
+    rsnix::gop::boot_marker("rsnix: usb init");
+    if !NO_USB {
+        rsnix::usb::init();
+    } else {
+        rsnix::serial_println!("usb: init skipped (stopgap) — BIOS USB-Legacy owns input");
+    }
+    rsnix::gop::boot_marker("rsnix: ehci init");
+    if !NO_USB {
+        rsnix::ehci::init();
+    } else {
+        rsnix::serial_println!("ehci: init skipped (stopgap)");
+    }
+    rsnix::gop::boot_marker("rsnix: uhci init");
+    if !NO_USB {
+        rsnix::uhci::init();
+    } else {
+        rsnix::serial_println!("uhci: init skipped (stopgap)");
+    }
+    if rsnix::ps2::mouse_present()
+        || rsnix::usb::controller_up()
+        || rsnix::ehci::controller_up()
+        || rsnix::uhci::controller_up()
+    {
+        rsnix::gop::boot_marker("rsnix: cursor spawn");
         rsnix::cursor::spawn();
     } else {
         rsnix::serial_println!("cursor: no mouse — overlay disabled");
     }
+    rsnix::gop::boot_marker("rsnix: shell run");
+    // The shell REPL is about to start: from here on task 0 may legitimately
+    // park in poll_key with a fixed frame, so the watchdog's boot-phase spin
+    // rule for task 0 is disarmed (boot-phase hangs already panicked).
+    rsnix::sched::mark_shell_running();
     // Shell-entry self-check: verify the vt grid structs are sane right
     // before the shell's first print.  The OptiPlex crashes in the first
     // banner write when the cells VecData (or the shadow) holds the
-- 
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