add page cache with read-ahead and dirty writeback, file-backed and anonymous mmap with CoW, VAD-based virtual memory replacing the old user region model, PFN database with eviction and reclaim, file identity for cross-open section sharing, FAT32 path cache and per-file cluster chain cache, serial.sys for COM1 keyboard input, xHCI MSI with INTx and polled fallback, PciEnableMsiAuto, waitable input queue, KeWaitForAnyEvent, per-process thread info syscall, expanded kernel stats (PFN/PTE/VAD/file-cache/disk), pool allocation tags, async I/O user buffer locking, file flush on close, add docs.md.

code/drivers/storage/ahci/ahci.c

@@ -58,20 +58,20 @@ static inline uint64_t cmd_tbl_phys(AHCI_DRIVE *drv, int slot) {
 static KSTATUS port_init_memory(AHCI_DRIVE *drv) {
     uint64_t flags = PAGE_PRESENT | PAGE_WRITE | PAGE_NOCACHE;
 
-    drv->structPhys = MmAllocateContiguous(PORT_PAGES_STRUCT);
+    drv->structPhys = MmPfnAllocateContiguous(PORT_PAGES_STRUCT, MmPfnUseDma);
     if (!drv->structPhys) return STATUS_NO_MEMORY;
     drv->structVirt = g_hal->PhysToVirt(drv->structPhys);
     // Force NOCACHE on DMA descriptor memory.
-    MmSetPageProtect((uintptr_t)drv->structVirt,
+    MmPteProtectRange((uintptr_t)drv->structVirt,
                      PORT_PAGES_STRUCT * 4096, flags);
     memset(drv->structVirt, 0, PORT_PAGES_STRUCT * 4096);
 
-    drv->bouncePhys = MmAllocateContiguous(BOUNCE_PAGES);
+    drv->bouncePhys = MmPfnAllocateContiguous(BOUNCE_PAGES, MmPfnUseDma);
     if (!drv->bouncePhys) return STATUS_NO_MEMORY;
     drv->bounceVirt = g_hal->PhysToVirt(drv->bouncePhys);
     // Bounce buffer: NOCACHE to ensure CPU writes reach physical memory
     // before the HBA's DMA engine reads them.
-    MmSetPageProtect((uintptr_t)drv->bounceVirt,
+    MmPteProtectRange((uintptr_t)drv->bounceVirt,
                      BOUNCE_PAGES * 4096, flags);
     memset(drv->bounceVirt, 0, BOUNCE_BYTES);
 
@@ -203,6 +203,9 @@ static void AhciIsr(void) {
 // Blocks the current thread until the ISR signals completionEvent.
 
 static KSTATUS port_issue_cmd(AHCI_DRIVE *drv) {
+    if (drv->controller && drv->controller->pollingMode)
+        return port_issue_cmd_poll(drv);
+
     HBA_PORT *port = drv->port;
 
     // Clear stale IS and snapshot before issuing so we don't mis-read a
@@ -647,12 +650,25 @@ static KSTATUS AhciStartController(AHCI_CONTROLLER* ctl) {
              ctl->pciInfo.VendorId,
              ctl->pciInfo.DeviceId);
 
-    st = PciGetInterrupt(ctl->pdo, &ctl->irq);
-    if (!KSUCCESS(st) || ctl->irq == 0xFF) {
-        DbgPrint("AHCI: no PCI IRQ wired - cannot use interrupt-driven mode\n");
-        return KSUCCESS(st) ? STATUS_NOT_SUPPORTED : st;
+    ctl->irq = 0xFFu;
+    ctl->usingMsi = false;
+    ctl->pollingMode = false;
+
+    st = PciEnableMsiAuto(ctl->pdo, &ctl->irq);
+    if (KSUCCESS(st)) {
+        ctl->usingMsi = true;
+        DbgPrint("AHCI: using MSI IRQ slot %u\n", (unsigned)ctl->irq);
+    } else {
+        KSTATUS intxStatus = PciGetInterrupt(ctl->pdo, &ctl->irq);
+        if (KSUCCESS(intxStatus) && ctl->irq != 0xFFu) {
+            DbgPrint("AHCI: using legacy INTx IRQ %u\n", (unsigned)ctl->irq);
+        } else {
+            ctl->irq = 0xFFu;
+            ctl->pollingMode = true;
+            DbgPrint("AHCI: no MSI/INTx interrupt available; using polled command completion (msi=0x%x intx=0x%x)\n",
+                     st, intxStatus);
+        }
     }
-    DbgPrint("AHCI: PCI IRQ line = %u\n", (unsigned)ctl->irq);
 
     st = PciGetBar(ctl->pdo, AHCI_PCI_BAR_ABAR, &ctl->abar);
     if (!KSUCCESS(st)) {
@@ -674,10 +690,13 @@ static KSTATUS AhciStartController(AHCI_CONTROLLER* ctl) {
         return st;
     }
 
-    st = PciEnableDevice(ctl->pdo,
-                         PCI_ENABLE_MEMORY |
-                         PCI_ENABLE_BUSMASTER |
-                         PCI_ENABLE_INTX);
+    uint32_t enableFlags = PCI_ENABLE_MEMORY | PCI_ENABLE_BUSMASTER;
+    if (ctl->usingMsi || ctl->pollingMode)
+        enableFlags |= PCI_DISABLE_INTX;
+    else
+        enableFlags |= PCI_ENABLE_INTX;
+
+    st = PciEnableDevice(ctl->pdo, enableFlags);
     if (!KSUCCESS(st)) {
         DbgPrint("AHCI: PciEnableDevice failed: 0x%x\n", st);
         return st;
@@ -831,11 +850,16 @@ static KSTATUS AhciStartController(AHCI_CONTROLLER* ctl) {
                  ctl->pciInfo.Address.Device,
                  ctl->pciInfo.Address.Function);
 
-    KeIrqRegister(ctl->irq, AhciIsr);
+    if (!ctl->pollingMode) {
+        KeIrqRegister(ctl->irq, AhciIsr);
+        DbgPrint("AHCI: ISR registered on IRQ %u (%s); controller drives=%d\n",
+                 (unsigned)ctl->irq, ctl->usingMsi ? "MSI" : "INTx", ctl->driveCount);
+    } else {
+        DbgPrint("AHCI: controller started in polling mode; controller drives=%d\n",
+                 ctl->driveCount);
+    }
     ctl->started = true;
     ctl->fdo->PnpState = DevicePnpStarted;
-    DbgPrint("AHCI: ISR registered on IRQ %u; controller drives=%d\n",
-             (unsigned)ctl->irq, ctl->driveCount);
 
     return STATUS_SUCCESS;
 }