move keyboard and mouse out of HAL into a standalone ps2.sys driver, implement usb stack with xhci controller discovery, hid keyboard/mouse, and bulk-only mass storage, add pci msi support with capability chain walking and software irq vector allocation (slots 16-23), rewrite user virtual memory as a USER_VA_REGION descriptor arena with per-process ownership tracking and guard page support, replacing the old bump allocator and top-down image region, add MmCreateUserRegion/MmDestroyAllUserRegions so process teardown reclaims all user va in one pass, allocate a pool-backed shadow framebuffer in hal_screen to fix cursor tearing and scroll corruption, reserve ap trampoline page below 1mb in uefi bootloader before boot services exit, rewrite memset/memcpy/memmove/memcmp with __stosq/__movsq intrinsics, promote driver flag literals to macros and add multi-tu STANDALONE_DRIVERS table to build.c, split rtl8139/rtl816x into header+source, rename KbReadScancode to KbReadKey, improve page fault output with MmDebugDescribeAddress and user region dump, fix %p to %016llX throughout.

code/kernel/ke_irq.c

@@ -10,6 +10,8 @@
 
 #define MAX_IRQS 24
 #define MAX_IRQ_HANDLERS 8
+#define MSI_IRQ_FIRST 16u
+#define MSI_IRQ_LAST  23u
 
 typedef struct IRQ_HANDLER_LIST {
     void (*Handlers[MAX_IRQ_HANDLERS])(void);
@@ -17,6 +19,7 @@ typedef struct IRQ_HANDLER_LIST {
 } IRQ_HANDLER_LIST;
 
 static IRQ_HANDLER_LIST gIrqHandlers[MAX_IRQS];
+static bool gIrqSoftwareVector[MAX_IRQS];
 static const HAL_API *gHal;
 
 static KIRQL KiIrqToIrql(uint8_t irq) {
@@ -30,6 +33,23 @@ void KeIrqInitialize(const HAL_API *hal) {
     gHal = hal;
 }
 
+__declspec(dllexport) KSTATUS KeIrqAllocateMsiVector(uint8_t* outIrq) {
+    if (!outIrq) return STATUS_INVALID_PARAMETER;
+
+    for (uint8_t irq = MSI_IRQ_FIRST; irq <= MSI_IRQ_LAST; irq++) {
+        IRQ_HANDLER_LIST* list = &gIrqHandlers[irq];
+        if (!gIrqSoftwareVector[irq] && list->Count == 0) {
+            gIrqSoftwareVector[irq] = true;
+            *outIrq = irq;
+            DbgPrint("KeIrq: allocated MSI vector slot IRQ %u vector 0x%02x\n",
+                     irq, 0x20u + irq);
+            return STATUS_SUCCESS;
+        }
+    }
+
+    return STATUS_NO_MEMORY;
+}
+
 __declspec(dllexport) void KeIrqRegister(uint8_t irq, void (*handler)(void)) {
     if (irq >= MAX_IRQS || !handler) return;
 
@@ -45,7 +65,8 @@ __declspec(dllexport) void KeIrqRegister(uint8_t irq, void (*handler)(void)) {
     }
 
     list->Handlers[list->Count++] = handler;
-    gHal->Intc.RouteIrq(irq);
+    if (!gIrqSoftwareVector[irq])
+        gHal->Intc.RouteIrq(irq);
 }
 
 void KeIrqDispatch(uint8_t irq) {
@@ -71,9 +92,9 @@ void KeIrqDispatch(uint8_t irq) {
         }
     }
 
-    // Handlers are no longer allowed to context-switch directly.  Timer IRQs
+    // Handlers are no longer allowed to context-switch directly. Timer IRQs
     // only request rescheduling; KiExitInterrupt performs the switch after this
-    // function returns, so the EOI is guaranteed to be sent first.  Keep the
+    // function returns, so the EOI is guaranteed to be sent first. Keep the
     // software level at DIRQL until after the controller has been acknowledged.
     gHal->Intc.SendEoi();