diff options
Diffstat (limited to 'boot')
| -rw-r--r-- | boot/entry.asm | 79 | ||||
| -rw-r--r-- | boot/load.c | 6 |
2 files changed, 82 insertions, 3 deletions
diff --git a/boot/entry.asm b/boot/entry.asm index 1f421ea..452de01 100644 --- a/boot/entry.asm +++ b/boot/entry.asm @@ -70,6 +70,12 @@ %define VESA_FRAMEBUFFER_OFFSET 0x2a ; Framebuffer offset in mode info %define VESA_LFB_FLAG 0x4000 ; Enable LFB flag +; MMAP constants +%define MMAP_START 0x400 ; Starts at 0x400, ends at 0x500 +%define MMAP_SIZE 0x18 ; Struct size +%define MMAP_SIG 0x0534d4150 ; Signature ("SMAP") +%define MMAP_BIOS_MAGIC 0xe820 ; BIOS int 15h code to get address map + ; A20 constants %define A20_GATE 0x92 ; Fast A20 gate %define A20_ENABLED 0b10 ; Bit 1 defines whether A20 is enabled @@ -234,6 +240,54 @@ video_map: .bpp dw VIDEO_BPP .framebuffer dd 0 +; Tries to load a memory map using BIOS INT 15h and e820h +memory_map: + xor ebx, ebx ; Must be 0 by spec + xor bp, bp + mov edx, MMAP_SIG ; "SMAP" in hex + mov eax, MMAP_BIOS_MAGIC ; Specify MMAP information + mov [es:di + 20], dword 1 ; Force a valid ACPI entry + mov ecx, MMAP_SIZE ; Request struct size + int MISC_INT ; BIOS interrupt + jc .fail ; Carry means "unsupported function" + mov edx, MMAP_SIG ; Mov for verification + cmp eax, edx ; Verification: Must be "SMAP" + jne .fail ; Result wasn't correct signature + test ebx, ebx ; Is size >1 + je .fail ; Nope, worthless :( + jmp .loop +.next: + mov eax, MMAP_BIOS_MAGIC ; Re-move because 0x15 clears or sth + mov [es:di + 20], dword 1 ; Force a valid ACPI entry + mov ecx, MMAP_SIZE ; Request struct size + int MISC_INT ; BIOS interrupt + jc .done ; Carry means "end of list already reached" + mov edx, MMAP_SIG ; Repair register (safety first!) +.loop: + jcxz .skip ; Skip 0-length entries + cmp cl, 20 ; Is the response correct ACPI spec (24 byte)? + jbe .notext ; Nope? Jump! + test byte [es:di + 20], 1 ; Is the "ignore this data" bit clear? + je .skip ; Yep? Skip! +.notext: + mov ecx, [es:di + 8] ; Get lower 32 bits of region + or ecx, [es:di + 12] ; "Or" with upper 32 bits to test for zero + jz .skip ; It's zero, skip! + inc bp + add di, MMAP_SIZE ; Else, next! +.skip: + test ebx, ebx ; If ebx is 0, list is complete + jne .next ; Else, next! +.done: + mov [mmap_cnt], bp + clc ; Clear carry + ret ; Finished! +.fail: + stc ; Set "unsupported function" + ret ; Finished! + +mmap_cnt: dd 0 + ; Variables disk_error_msg db "Disk error!", NEWLINE, RETURN, NULL lba_error_msg db "LBA error!", NEWLINE, RETURN, NULL @@ -329,6 +383,14 @@ stage_two: mov [dest], bx call inode_load + ; Load mmap + xor eax, eax + mov es, eax + mov edi, MMAP_START + push edi + call memory_map + push edi + ; Set video mode call video_map @@ -373,6 +435,13 @@ protected_mode_enter: bits 32 ; Woah, so big! protected_mode: + mov ecx, [mmap_cnt] ; Get mmap entry count + mov [mem_info + 8], ecx ; Count of maps + pop ecx ; End of memory map + mov [mem_info + 4], ecx ; Ending boundary of struct + pop ecx ; Start of memory map + mov [mem_info], ecx ; Starting boundary of struct + mov ax, GDT_DATA_OFFSET ; Data segment offset of GDT mov ds, ax mov es, ax @@ -388,10 +457,20 @@ protected_mode: mov eax, vid_info ; Pass VBE struct to kernel push eax ; Push as second kernel parameter + mov eax, mem_info ; Pass meminfo to kernel + push eax ; Push as first kernel parameter + mov edx, KERNEL_POSITION lea eax, [edx] call eax +; Memory map +align 16 +mem_info: + dd 0 ; Start address + dd 0 ; End address + dd 0 ; Count + ; GDT align 32 gdt: ; GDTs start diff --git a/boot/load.c b/boot/load.c index b243629..34c6af8 100644 --- a/boot/load.c +++ b/boot/load.c @@ -133,16 +133,16 @@ int find_inode(const char *name, int dir_inode); void serial_install(void); void serial_print(const char *data); -int main(void *data) +int main(void *data1, void *data2) { serial_install(); serial_print("Loaded bootloader!\n"); heap = 0xf00000; - void (*entry)(void *); + void (*entry)(void *, void *); *(void **)(&entry) = read_inode(get_inode(find_inode("kernel.bin", 2))); if (entry) { serial_print("Loaded kernel!\n"); - entry(data); + entry(data1, data2); } else { serial_print("Couldn't find kernel!\n"); } |