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/user/personalities/posix/posix_io.c

@@ -81,7 +81,8 @@ __declspec(dllexport) ssize_t read(int fd, void* buf, size_t count) {
             return (ssize_t)count;
         case FD_FILE: {
             size_t got = 0;
-            uint32_t s = SysReadFile(e->KHandle, buf, count, &got);
+            SYS_FILE_IO_REQUEST req = SysMakeFileIoRequest(e->KHandle, buf, count, &got);
+            uint32_t s = SysReadFile(&req);
             if (s != 0 && got == 0) { errno = PosixStatusToErrno(s); return -1; }
             return (ssize_t)got;
         }
@@ -115,7 +116,8 @@ __declspec(dllexport) ssize_t write(int fd, const void* buf, size_t count) {
             return (ssize_t)count;
         case FD_FILE: {
             size_t written = 0;
-            uint32_t s = SysWriteFile(e->KHandle, buf, count, &written);
+            SYS_FILE_IO_REQUEST req = SysMakeFileIoRequest(e->KHandle, buf, count, &written);
+            uint32_t s = SysWriteFile(&req);
             if (s != 0 && written == 0) { errno = PosixStatusToErrno(s); return -1; }
             return (ssize_t)written;
         }