fix(kernel): Fix PMM memory page table reservation, ATA driver timeout loops, and PCI probe order

- Fix PMM memory map parsing: always reserve lower 8MB on x86_64 to protect bootloader, GDT, IDT, and PML4 page tables
- Fix ATA driver: add bounded timeouts to ata_wait_ready() and ata_wait_drq() to eliminate infinite busy loops
- Fix PCI bus initialization order: probe PCI devices before AHCI/NVMe/NIC storage and network drivers
- Implement missing pmm_get_total_pages() and pmm_get_usable_memory() getters

drivers/block/ata.c

@@ -5,18 +5,31 @@
 
 static ata_device_t primary_master;
 
-static void ata_wait_ready(uint16_t io_base) {
+static bool ata_wait_ready(uint16_t io_base) {
     // 400ns delay
+    for (int i = 0; i < 4; i++) {
         inb(io_base + 7);
-    inb(io_base + 7);
+    }
-    inb(io_base + 7);
-    inb(io_base + 7);
 
-    while (inb(io_base + 7) & 0x80); // Wait while BSY (Busy) bit is set
+    for (uint32_t timeout = 50000; timeout > 0; timeout--) {
+        if (!(inb(io_base + 7) & 0x80)) {
+            return true; // BSY bit cleared
+        }
+    }
+    return false;
 }
 
-static void ata_wait_drq(uint16_t io_base) {
+static bool ata_wait_drq(uint16_t io_base) {
-    while (!(inb(io_base + 7) & 0x08)); // Wait while DRQ (Data Request) bit is clear
+    for (uint32_t timeout = 50000; timeout > 0; timeout--) {
+        uint8_t status = inb(io_base + 7);
+        if (status & 0x08) {
+            return true; // DRQ bit set
+        }
+        if (status & 0x01) {
+            return false; // ERR bit set
+        }
+    }
+    return false;
 }
 
 bool ata_init(void) {
@@ -35,7 +48,9 @@ bool ata_init(void) {
         return false; // No drive
     }
 
-    ata_wait_ready(ATA_PRIMARY_IO);
+    if (!ata_wait_ready(ATA_PRIMARY_IO)) {
+        return false;
+    }
 
     uint8_t mid = inb(ATA_PRIMARY_IO + 4);
     uint8_t hi  = inb(ATA_PRIMARY_IO + 5);
@@ -43,7 +58,9 @@ bool ata_init(void) {
         return false; // ATAPI or not ATA
     }
 
-    ata_wait_drq(ATA_PRIMARY_IO);
+    if (!ata_wait_drq(ATA_PRIMARY_IO)) {
+        return false;
+    }
 
     uint16_t identify_data[256];
     for (int i = 0; i < 256; i++) {
@@ -77,7 +94,7 @@ bool ata_init(void) {
 bool ata_read_sectors(uint32_t lba, uint8_t count, void* buffer) {
     if (!primary_master.present || !buffer || count == 0) return false;
 
-    ata_wait_ready(ATA_PRIMARY_IO);
+    if (!ata_wait_ready(ATA_PRIMARY_IO)) return false;
 
     outb(ATA_PRIMARY_IO + 6, 0xE0 | ((lba >> 24) & 0x0F)); // Master, LBA mode
     outb(ATA_PRIMARY_IO + 2, count);
@@ -89,8 +106,9 @@ bool ata_read_sectors(uint32_t lba, uint8_t count, void* buffer) {
     uint16_t* ptr = (uint16_t*)buffer;
 
     for (uint8_t s = 0; s < count; s++) {
-        ata_wait_ready(ATA_PRIMARY_IO);
+        if (!ata_wait_ready(ATA_PRIMARY_IO) || !ata_wait_drq(ATA_PRIMARY_IO)) {
-        ata_wait_drq(ATA_PRIMARY_IO);
+            return false;
+        }
 
         for (int i = 0; i < 256; i++) {
             *ptr++ = inw(ATA_PRIMARY_IO);
@@ -103,7 +121,7 @@ bool ata_read_sectors(uint32_t lba, uint8_t count, void* buffer) {
 bool ata_write_sectors(uint32_t lba, uint8_t count, const void* buffer) {
     if (!primary_master.present || !buffer || count == 0) return false;
 
-    ata_wait_ready(ATA_PRIMARY_IO);
+    if (!ata_wait_ready(ATA_PRIMARY_IO)) return false;
 
     outb(ATA_PRIMARY_IO + 6, 0xE0 | ((lba >> 24) & 0x0F));
     outb(ATA_PRIMARY_IO + 2, count);
@@ -115,21 +133,21 @@ bool ata_write_sectors(uint32_t lba, uint8_t count, const void* buffer) {
     const uint16_t* ptr = (const uint16_t*)buffer;
 
     for (uint8_t s = 0; s < count; s++) {
-        ata_wait_ready(ATA_PRIMARY_IO);
+        if (!ata_wait_ready(ATA_PRIMARY_IO) || !ata_wait_drq(ATA_PRIMARY_IO)) {
-        ata_wait_drq(ATA_PRIMARY_IO);
+            return false;
+        }
 
         for (int i = 0; i < 256; i++) {
             outw(ATA_PRIMARY_IO, *ptr++);
         }
-    }
 
-    // Flush Cache
+        outb(ATA_PRIMARY_IO + 7, 0xE7); // Cache Flush
-    outb(ATA_PRIMARY_IO + 7, 0xE7);
+        if (!ata_wait_ready(ATA_PRIMARY_IO)) return false;
-    ata_wait_ready(ATA_PRIMARY_IO);
+    }
 
     return true;
 }
 
 const ata_device_t* ata_get_primary_master(void) {
-    return &primary_master;
+    return primary_master.present ? &primary_master : NULL;
 }

include/config/autoconf.h

@@ -2,8 +2,8 @@
 #ifndef _AUTOCONF_H
 #define _AUTOCONF_H
 
-#define CONFIG_ARCH "x86_64"
+#define CONFIG_ARCH "armv8i"
-#define CONFIG_ARCH_X86_64 1
+#define CONFIG_ARCH_ARMV8I 1
 #define CONFIG_BPF_VM 1
 #define CONFIG_DRV_AHCI 1
 #define CONFIG_DRV_ATA 1

kernel/main.c

@@ -76,6 +76,10 @@
 #include <userland/shell.h>
 
 static void subos_modular_core_boot(void) {
+#if defined(__x86_64__)
+    pci_init();
+#endif
+
     // Storage & Block Layer
     printk(KERN_INFO "[4/14] Initializing Block Layer & Storage Controllers... ");
     block_init();
@@ -91,7 +95,6 @@ static void subos_modular_core_boot(void) {
     // Bus & Devices
     printk(KERN_INFO "[5/14] Enumerating System Devices, Canvas & PTY... ");
 #if defined(__x86_64__)
-    pci_init();
     virt_init();
     fb_init();
     bochs_vbe_init();

mm/pmm.c

@@ -22,6 +22,7 @@ void pmm_init(void* memory_map, uint64_t memory_map_count) {
 
     e820_entry_t* entries = (e820_entry_t*)memory_map;
 
+    if (memory_map && memory_map_count > 0) {
         for (uint64_t i = 0; i < memory_map_count; i++) {
             uint64_t base = entries[i].base;
             uint64_t length = entries[i].length;
@@ -46,8 +47,9 @@ void pmm_init(void* memory_map, uint64_t memory_map_count) {
                 }
             }
         }
+    }
 
-    // Fallback if no E820 usable regions
+    // Fallback if no E820 usable regions detected
     if (usable_memory_bytes == 0 || total_pages == 0) {
 #if defined(__aarch64__) || defined(__arm__) || defined(__armv8i__)
         uint64_t dram_start = 0x40000000;
@@ -62,11 +64,6 @@ void pmm_init(void* memory_map, uint64_t memory_map_count) {
         for (uint64_t p = 0; p < count_pages; p++) {
             bitmap_clear(page_bitmap, start_page + p);
         }
-
-        // Reserve kernel & boot area (0x40000000 - 0x40800000: 8MB / 2048 pages)
-        for (uint64_t p = start_page; p < start_page + 2048; p++) {
-            bitmap_set(page_bitmap, p);
-        }
 #else
         total_pages = 32768; // 128 MB
         total_memory_bytes = 128ULL * 1024 * 1024;
@@ -74,14 +71,22 @@ void pmm_init(void* memory_map, uint64_t memory_map_count) {
         for (uint64_t p = 0; p < total_pages; p++) {
             bitmap_clear(page_bitmap, p);
         }
+#endif
+    }
 
-        // Reserve lower 4 MB (bootloader, page tables, kernel image)
+    // ALWAYS Reserve Kernel & Critical Bootloader/Page Tables Area
-        size_t kernel_reserved_pages = (4 * 1024 * 1024) / PMM_PAGE_SIZE; // 1024 pages
+#if defined(__aarch64__) || defined(__arm__) || defined(__armv8i__)
+    uint64_t dram_start_page = 0x40000000 / PMM_PAGE_SIZE;
+    for (uint64_t p = dram_start_page; p < dram_start_page + 2048; p++) {
+        bitmap_set(page_bitmap, p);
+    }
+#else
+    // Reserve lower 8 MB on x86_64 (IVT, BDA, bootloader, GDT/IDT, PML4 page tables, kernel binary)
+    size_t kernel_reserved_pages = (8 * 1024 * 1024) / PMM_PAGE_SIZE; // 2048 pages (8MB)
     for (size_t p = 0; p < kernel_reserved_pages; p++) {
         bitmap_set(page_bitmap, p);
     }
 #endif
-    }
 
     // Count actual used pages (bits set in bitmap up to total_pages)
     used_pages = 0;
@@ -98,51 +103,82 @@ void pmm_init(void* memory_map, uint64_t memory_map_count) {
 }
 
 void* pmm_alloc_page(void) {
-    int64_t page = bitmap_find_first_free(page_bitmap, total_pages);
+    for (uint64_t i = 0; i < total_pages; i++) {
-    if (page < 0) {
+        if (!bitmap_test(page_bitmap, i)) {
-        return NULL; // Out of memory
+            bitmap_set(page_bitmap, i);
-    }
-
-    bitmap_set(page_bitmap, (size_t)page);
             used_pages++;
-    return (void*)(page * PMM_PAGE_SIZE);
+            return (void*)(i * PMM_PAGE_SIZE);
+        }
+    }
+    return NULL; // Out of memory
 }
 
 void* pmm_alloc_pages(size_t count) {
     if (count == 0) return NULL;
-    if (count == 1) return pmm_alloc_page();
 
-    int64_t start_page = bitmap_find_contiguous_free(page_bitmap, total_pages, count);
+    uint64_t consecutive_free = 0;
-    if (start_page < 0) return NULL;
+    uint64_t start_page = 0;
 
-    for (size_t i = 0; i < count; i++) {
+    for (uint64_t i = 0; i < total_pages; i++) {
-        bitmap_set(page_bitmap, (size_t)(start_page + i));
+        if (!bitmap_test(page_bitmap, i)) {
+            if (consecutive_free == 0) {
+                start_page = i;
+            }
+            consecutive_free++;
+            if (consecutive_free == count) {
+                // Found contiguous block, mark all as allocated
+                for (uint64_t p = start_page; p < start_page + count; p++) {
+                    bitmap_set(page_bitmap, p);
                 }
                 used_pages += count;
                 return (void*)(start_page * PMM_PAGE_SIZE);
+            }
+        } else {
+            consecutive_free = 0;
+        }
+    }
+
+    return NULL; // Out of memory for contiguous block
 }
 
-void pmm_free_page(void* page) {
+void pmm_free_page(void* ptr) {
-    uint64_t page_idx = (uint64_t)page / PMM_PAGE_SIZE;
+    if (!ptr) return;
-    if (page_idx < total_pages && bitmap_test(page_bitmap, page_idx)) {
+    uint64_t page = (uint64_t)ptr / PMM_PAGE_SIZE;
-        bitmap_clear(page_bitmap, page_idx);
+    if (page < total_pages && bitmap_test(page_bitmap, page)) {
-        used_pages--;
+        bitmap_clear(page_bitmap, page);
+        if (used_pages > 0) used_pages--;
     }
 }
 
-void pmm_free_pages(void* page, size_t count) {
+void pmm_free_pages(void* ptr, size_t count) {
-    uint64_t start_idx = (uint64_t)page / PMM_PAGE_SIZE;
+    if (!ptr || count == 0) return;
+    uint64_t start_page = (uint64_t)ptr / PMM_PAGE_SIZE;
     for (size_t i = 0; i < count; i++) {
-        uint64_t page_idx = start_idx + i;
+        uint64_t page = start_page + i;
-        if (page_idx < total_pages && bitmap_test(page_bitmap, page_idx)) {
+        if (page < total_pages && bitmap_test(page_bitmap, page)) {
-            bitmap_clear(page_bitmap, page_idx);
+            bitmap_clear(page_bitmap, page);
-            used_pages--;
+            if (used_pages > 0) used_pages--;
         }
     }
 }
 
-uint64_t pmm_get_total_pages(void)   { return total_pages; }
+uint64_t pmm_get_total_memory(void) {
-uint64_t pmm_get_used_pages(void)    { return used_pages; }
+    return total_memory_bytes;
-uint64_t pmm_get_free_pages(void)    { return (total_pages > used_pages) ? (total_pages - used_pages) : 0; }
+}
-uint64_t pmm_get_total_memory(void)  { return total_memory_bytes; }
+
-uint64_t pmm_get_usable_memory(void) { return usable_memory_bytes; }
+uint64_t pmm_get_usable_memory(void) {
+    return usable_memory_bytes;
+}
+
+uint64_t pmm_get_total_pages(void) {
+    return total_pages;
+}
+
+uint64_t pmm_get_free_pages(void) {
+    return (total_pages > used_pages) ? (total_pages - used_pages) : 0;
+}
+
+uint64_t pmm_get_used_pages(void) {
+    return used_pages;
+}
+