arch: i386: add multiboot support

Add support for the multiboot specification. These files will allow the
kernel to read the multiboot header information as well as the provided
memory map.

Signed-off-by: Danny Holman <dholman@gymli.org>

2 files changed, 127 insertions, 0 deletions

diff --git a/arch/i386/include/kernel/multiboot.h b/arch/i386/include/kernel/multiboot.h
new file mode 100644
index 0000000..5825816
--- /dev/null
+++ b/arch/i386/include/kernel/multiboot.h
@@ -0,0 +1,104 @@
+#ifndef I386_MULTIBOOT_H
+#define I386_MULTIBOOT_H
+
+#include <stdint.h>
+
+#define MBOOT_HEADER_MAGIC      0x1BADB002
+#define MBOOT_LOADER_MAGIC      0x2BADB002
+
+// Multiboot flags
+#define MBOOT_INFO_MMAP         0x00000001
+#define MBOOT_INFO_BOOTDEV      0x00000002
+#define MBOOT_INFO_CMDLINE      0x00000004
+#define MBOOT_INFO_MODS         0x00000008
+#define MBOOT_INFO_AOUT_SYMS    0x00000010
+#define MBOOT_INFO_ELF_HEADER   0x00000020
+#define MBOOT_INFO_MEM_MAP      0x00000040
+#define MBOOT_INFO_DRIVE_INFO   0x00000080
+#define MBOOT_INFO_CONFIG_TBL   0x00000100
+#define MBOOT_INFO_BL_NAME      0x00000200
+#define MBOOT_INFO_APM_TBL      0x00000400
+#define MBOOT_INFO_VBE          0x00000800
+#define MBOOT_INFO_FRAMEBUFFER  0x00001000
+
+// Memory types
+#define MBOOT_MEM_AVAILABLE     1
+#define MBOOT_MEM_RESERVED      2
+#define MBOOT_MEM_ACPI_REC      3
+#define MBOOT_MEM_NVS           4
+#define MBOOT_MEM_BADRAM        5
+
+struct aout_symbol_table {
+        uint32_t tabsize;
+        uint32_t strsize;
+        uint32_t addr;
+        uint32_t reserved;
+};
+
+struct elf_section_header {
+        uint32_t num;
+        uint32_t size;
+        uint32_t addr;
+        uint32_t shndx;
+};
+
+struct mboot_header {
+        uint32_t magic;
+        uint32_t flags;
+        uint32_t checksum;
+        uint32_t header_addr;
+        uint32_t load_addr;
+        uint32_t load_end_addr;
+        uint32_t bss_end_addr;
+        uint32_t entry_addr;
+        uint32_t mode_type;
+        uint32_t width;
+        uint32_t height;
+        uint32_t depth;
+};
+
+struct mboot_info {
+        uint32_t flags;
+        uint32_t mem_lower;
+        uint32_t mem_upper;
+        uint32_t boot_device;
+        uint32_t cmdline;
+        uint32_t mods_count;
+        uint32_t mods_addr;
+        union {
+                struct aout_symbol_table aout_sym;
+                struct elf_section_header elf_sec;
+        } u;
+        uint32_t mmap_length;
+        uint32_t mmap_addr;
+        uint32_t drives_length;
+        uint32_t drives_addr;
+        uint32_t config_table;
+        uint32_t boot_loader_name;
+        uint32_t apm_table;
+        uint32_t vbe_control_info;
+        uint32_t vbe_mode_info;
+        uint16_t vbe_mode;
+        uint16_t vbe_interface_seg;
+        uint16_t vbe_interface_off;
+        uint16_t vbe_interface_len;
+        uint64_t framebuffer_addr;
+        uint32_t framebuffer_pitch;
+        uint32_t framebuffer_width;
+        uint32_t framebuffer_height;
+        uint8_t framebuffer_bpp;
+        uint8_t framebuffer_type;
+};
+
+struct mboot_mmap_entry {
+        uint32_t size;
+        uint32_t addr_low;
+        uint32_t addr_high;
+        uint32_t len_low;
+        uint32_t len_high;
+        uint32_t type;
+} __attribute__((packed));
+
+void i386_entry(uint32_t mboot_magic, struct mboot_info *header);
+
+#endif
diff --git a/arch/i386/kernel/multiboot.c b/arch/i386/kernel/multiboot.c
new file mode 100644
index 0000000..d7f0a65
--- /dev/null
+++ b/arch/i386/kernel/multiboot.c
@@ -0,0 +1,23 @@
+#include <kernel/multiboot.h>
+#include <kernel/tty.h>
+#include <kernel/panic.h>
+#include <kernel/io.h>
+
+void i386_entry(uint32_t mboot_magic, struct mboot_info *header) {
+        paging_init();
+        tty_init();
+
+        struct mboot_info *vheader = get_vaddr(header);
+        mark_bitmap(header, 1);
+        map_page(header, vheader, 0x003);
+
+        if (mboot_magic != MBOOT_LOADER_MAGIC)
+                panic("NOT BOOTED WITH MULTIBOOT BOOTLOADER");
+        if (!(vheader->flags >> 6 & 0x1))
+                panic("NO MEMORY MAP FROM BOOTLOADER");
+
+        gdt_install();
+        idt_install();
+        alloc_init(vheader);
+        kernel_main(vheader->cmdline);
+}