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.h

@@ -8,6 +8,7 @@
 #include <ntlite/ddi/io_driver.h>
 #include <ntlite/ddi/pci.h>
 #include <kernel/mm_phys.h>
+#include <kernel/mm_pfn.h>
 #include <kernel/mm_virt.h>
 #include <kernel/ke_debug.h>
 #include <kernel/ke_event.h>
@@ -367,6 +368,8 @@ struct AHCI_CONTROLLER {
     HBA_MEM*        hba;
     uint64_t        abarLength;
     uint8_t         irq;
+    bool            usingMsi;
+    bool            pollingMode;
 
     AHCI_DRIVE      drives[MAX_AHCI_DRIVES];
     int             driveCount;