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/apps/edit/edit.c

@@ -380,12 +380,14 @@ static void save_file(void) {
     for (int i = 0; i < gLineCount; i++) {
         size_t written = 0;
         if (gLines[i].len) {
-            st = SysWriteFile(h, gLines[i].text, (size_t)gLines[i].len, &written);
+            SYS_FILE_IO_REQUEST writeReq = SysMakeFileIoRequest(h, gLines[i].text, (size_t)gLines[i].len, &written);
+            st = SysWriteFile(&writeReq);
             if (st != 0) { SysCloseHandle(h); msg_set("save failed: write error"); return; }
         }
         if (i + 1 < gLineCount) {
             const char nl = '\n';
-            st = SysWriteFile(h, &nl, 1, &written);
+            SYS_FILE_IO_REQUEST newlineReq = SysMakeFileIoRequest(h, &nl, 1, &written);
+            st = SysWriteFile(&newlineReq);
             if (st != 0) { SysCloseHandle(h); msg_set("save failed: write error"); return; }
         }
     }
@@ -418,7 +420,9 @@ static void load_file(void) {
     char buf[512];
     size_t got = 0;
     bool truncated = false;
-    while (SysReadFile(h, buf, sizeof(buf), &got) == 0 && got > 0) {
+    for (;;) {
+        SYS_FILE_IO_REQUEST readReq = SysMakeFileIoRequest(h, buf, sizeof(buf), &got);
+        if (SysReadFile(&readReq) != 0 || got == 0) break;
         for (size_t i = 0; i < got; i++) {
             char c = buf[i];
             if (c == '\r') continue;