src/devicefs.h

@@ -0,0 +1,135 @@
+/**
+ * @file devicefs.h
+ * @brief Device filesystem (devicefs) subsystem.
+ *
+ * Provides a VFS interface at /dev for exposing block and character devices.
+ * Drivers register devices through the devicefs API, and each device is
+ * assigned a sequential number by device class (e.g., hdd1, hdd2, cd1).
+ *
+ * The devicefs owns device naming — drivers specify a class name (e.g., "hdd")
+ * and the devicefs appends a sequential number.
+ */
+
+#ifndef DEVICEFS_H
+#define DEVICEFS_H
+
+#include <stdint.h>
+#include <stddef.h>
+
+/** Maximum number of registered devices. */
+#define DEVICEFS_MAX_DEVICES 32
+
+/** Maximum length of a device class name (e.g., "hdd", "cd", "floppy"). */
+#define DEVICEFS_MAX_CLASS_NAME 16
+
+/** Maximum length of a full device name (class + number, e.g., "hdd1"). */
+#define DEVICEFS_MAX_DEV_NAME 32
+
+/** Device types. */
+#define DEVICEFS_BLOCK 0x01  /**< Block device (e.g., hard drives, CDs). */
+#define DEVICEFS_CHAR  0x02  /**< Character device (e.g., serial ports). */
+
+/**
+ * Block device operations.
+ *
+ * Block devices transfer data in fixed-size sectors.
+ */
+typedef struct devicefs_block_ops {
+    /** Read `count` sectors starting at `lba` into `buf`. Returns 0 on success. */
+    int (*read_sectors)(void *dev_data, uint32_t lba, uint32_t count, void *buf);
+
+    /** Write `count` sectors from `buf` starting at `lba`. Returns 0 on success. */
+    int (*write_sectors)(void *dev_data, uint32_t lba, uint32_t count, const void *buf);
+
+    /** Get the sector size in bytes. */
+    uint32_t (*sector_size)(void *dev_data);
+
+    /** Get total number of sectors. */
+    uint32_t (*sector_count)(void *dev_data);
+} devicefs_block_ops_t;
+
+/**
+ * Character device operations.
+ *
+ * Character devices transfer data as byte streams.
+ */
+typedef struct devicefs_char_ops {
+    /** Read up to `size` bytes into `buf`. Returns bytes read, or -1. */
+    int32_t (*read)(void *dev_data, uint32_t size, void *buf);
+
+    /** Write `size` bytes from `buf`. Returns bytes written, or -1. */
+    int32_t (*write)(void *dev_data, uint32_t size, const void *buf);
+} devicefs_char_ops_t;
+
+/**
+ * Registered device entry.
+ */
+typedef struct devicefs_device {
+    char name[DEVICEFS_MAX_DEV_NAME];    /**< Full device name (e.g., "hdd1"). */
+    char class_name[DEVICEFS_MAX_CLASS_NAME]; /**< Device class (e.g., "hdd"). */
+    uint8_t type;                         /**< DEVICEFS_BLOCK or DEVICEFS_CHAR. */
+    uint32_t number;                      /**< Assigned device number within class. */
+    int active;                           /**< 1 if registered, 0 if free. */
+
+    /** Device-specific operations (union of block/char). */
+    union {
+        devicefs_block_ops_t *block_ops;
+        devicefs_char_ops_t  *char_ops;
+    };
+
+    /** Opaque driver-specific data passed to operation callbacks. */
+    void *dev_data;
+} devicefs_device_t;
+
+/**
+ * Initialize the devicefs subsystem and mount at /dev.
+ *
+ * @return 0 on success, -1 on failure.
+ */
+int init_devicefs(void);
+
+/**
+ * Register a new block device.
+ *
+ * The devicefs assigns a sequential number within the class. For example,
+ * registering class "hdd" twice yields "hdd1" and "hdd2".
+ *
+ * @param class_name  Device class name (e.g., "hdd", "cd").
+ * @param ops         Block device operations.
+ * @param dev_data    Opaque data passed to operation callbacks.
+ * @return Pointer to the device entry, or NULL on failure.
+ */
+devicefs_device_t *devicefs_register_block(const char *class_name,
+                                           devicefs_block_ops_t *ops,
+                                           void *dev_data);
+
+/**
+ * Register a new character device.
+ *
+ * @param class_name  Device class name (e.g., "tty", "serial").
+ * @param ops         Character device operations.
+ * @param dev_data    Opaque data passed to operation callbacks.
+ * @return Pointer to the device entry, or NULL on failure.
+ */
+devicefs_device_t *devicefs_register_char(const char *class_name,
+                                          devicefs_char_ops_t *ops,
+                                          void *dev_data);
+
+/**
+ * Find a device by its full name (e.g., "hdd1").
+ *
+ * @param name Device name.
+ * @return Pointer to the device entry, or NULL if not found.
+ */
+devicefs_device_t *devicefs_find(const char *name);
+
+/**
+ * Get the next device number for a given class.
+ * This is called internally but may be useful for drivers.
+ *
+ * @param class_name Device class name.
+ * @return Next sequential number (starting from 1).
+ */
+uint32_t devicefs_next_number(const char *class_name);
+
+#endif /* DEVICEFS_H */

src/kernel.c

@@ -69,36 +69,65 @@ void kernel_main(uint32_t magic, uint32_t addr) {
     /* Initialize serial port first so all debug output goes to COM1 too */
     serial_init();
 
-    /* Early canary: write directly to VGA text buffer at 0xB8000.
-     * If the display is in text mode, this will show a bright magenta 'C'
-     * in the top-left corner before any subsystem is initialized. */
-    {
-        volatile uint16_t *vga = (volatile uint16_t *)0xB8000;
-        vga[0] = (uint16_t)'C' | (0x5F << 8); /* magenta on magenta = visible block */
-        vga[1] = (uint16_t)'O' | (0x5F << 8);
-        vga[2] = (uint16_t)'S' | (0x5F << 8);
-    }
+    /* Early VGA: write directly to the text buffer at 0xB8000 for boot
+     * progress that is visible even without the VGA driver initialized.
+     * Attribute 0x1F = white on blue. */
+    volatile uint16_t *early_vga = (volatile uint16_t *)0xB8000;
+    int early_pos = 0;
+
+    /* Helper macro: write a short string to early VGA */
+    #define EARLY_PRINT(s) do { \
+        const char *_p = (s); \
+        while (*_p) { \
+            early_vga[early_pos++] = (uint16_t)(unsigned char)*_p | (0x1F << 8); \
+            _p++; \
+        } \
+    } while(0)
+
+    /* Clear screen to blue */
+    for (int i = 0; i < 80 * 25; i++)
+        early_vga[i] = (uint16_t)' ' | (0x1F << 8);
+
+    EARLY_PRINT("ClaudeOS early boot");
+    early_pos = 80; /* Move to line 2 */
 
     if (magic != MULTIBOOT2_BOOTLOADER_MAGIC) {
+        EARLY_PRINT("ERROR: Bad magic=0x");
+        /* Print magic in hex */
+        const char *hex = "0123456789ABCDEF";
+        for (int i = 28; i >= 0; i -= 4)
+            early_vga[early_pos++] = (uint16_t)(unsigned char)hex[(magic >> i) & 0xF] | (0x4F << 8);
+        early_pos = 80 * 3;
+        EARLY_PRINT("Expected 0x36D76289 (Multiboot2)");
+        early_pos = 80 * 4;
+        EARLY_PRINT("Got MB1 magic? Checking grub.cfg...");
+
         offset_print("Invalid magic number: ");
         print_hex(magic);
-        return;
+
+        /* Hang with interrupts disabled so user can see the message */
+        for (;;) __asm__ volatile("hlt");
     }
     
+    EARLY_PRINT("Magic OK ");
     offset_print("Booting...\n");
 
     init_gdt();
+    EARLY_PRINT("GDT ");
     offset_print("GDT initialized\n");
     
     init_idt();
+    EARLY_PRINT("IDT ");
     offset_print("IDT initialized\n");
 
     init_pic();
     /* Unmask timer IRQ (IRQ0) explicitly */
     pic_clear_mask(0);
+    EARLY_PRINT("PIC ");
     offset_print("PIC initialized\n");
     
     init_pmm(addr);
+    EARLY_PRINT("PMM ");
     offset_print("PMM initialized\n");
 
     /* Scan Multiboot2 tags for the initrd module and framebuffer info */
@@ -152,6 +181,7 @@ void kernel_main(uint32_t magic, uint32_t addr) {
     }
 
     init_paging();
+    EARLY_PRINT("PAGING ");
     offset_print("Paging initialized\n");
 
     /* If GRUB provided a graphical framebuffer, identity-map it so
@@ -182,21 +212,25 @@ void kernel_main(uint32_t magic, uint32_t addr) {
     }
 
     init_kmalloc();
+    EARLY_PRINT("HEAP ");
     offset_print("Memory allocator initialized\n");
 
     /* Initialize CPIO ramdisk if module was loaded */
     if (initrd_start != 0) {
         cpio_init((const void *)initrd_start, initrd_end - initrd_start);
+        EARLY_PRINT("CPIO ");
         offset_print("CPIO ramdisk initialized\n");
     } else {
         offset_print("No initrd module found\n");
     }
 
     init_vfs();
+    EARLY_PRINT("VFS ");
     offset_print("VFS initialized\n");
 
     if (initrd_start != 0) {
         init_initrd_fs();
+        EARLY_PRINT("INITRD ");
         offset_print("Initrd filesystem mounted\n");
 
         /* Test VFS: read a file from the initrd */
@@ -214,6 +248,7 @@ void kernel_main(uint32_t magic, uint32_t addr) {
     }
 
     init_tss();
+    EARLY_PRINT("TSS ");
     offset_print("TSS initialized\n");
 
     init_syscalls();
@@ -228,6 +263,9 @@ void kernel_main(uint32_t magic, uint32_t addr) {
     init_drivers();
     offset_print("Drivers initialized\n");
 
+    /* At this point the VGA driver has been initialized and taken over
+     * the display. The early VGA text is no longer visible. */
+
     /* Show memory statistics and boot progress on VGA */
     vga_show_mem_stats();
     vga_puts("Boot complete.\n\n");