:: commit 35181c2b5471e8d37f3f71a3af47bd3ffbc7da68
gpt: Embed stage2 code within GPT structures so an extra partition is not needed
diff --git a/Makefile b/Makefile
index 26061861..4969da33 100644
--- a/Makefile
+++ b/Makefile
@@ -40,19 +40,19 @@ limine-install: limine-install.c
test.hdd:
rm -f test.hdd
dd if=/dev/zero bs=1M count=0 seek=64 of=test.hdd
- parted -s test.hdd mklabel msdos
+ parted -s test.hdd mklabel gpt
parted -s test.hdd mkpart primary 2048s 100%
echfs-test: all limine-install test.hdd
$(MAKE) -C test
- echfs-utils -m -p0 test.hdd quick-format 512 > part_guid
+ echfs-utils -g -p0 test.hdd quick-format 512 > part_guid
sed "s/@GUID@/`cat part_guid`/g" < test/limine.cfg > limine.cfg.tmp
- echfs-utils -m -p0 test.hdd import limine.cfg.tmp limine.cfg
+ echfs-utils -g -p0 test.hdd import limine.cfg.tmp limine.cfg
rm -f limine.cfg.tmp part_guid
- echfs-utils -m -p0 test.hdd import stage2.map boot/stage2.map
- echfs-utils -m -p0 test.hdd import test/test.elf boot/test.elf
- echfs-utils -m -p0 test.hdd import test/bg.bmp boot/bg.bmp
- echfs-utils -m -p0 test.hdd import test/font.bin boot/font.bin
+ echfs-utils -g -p0 test.hdd import stage2.map boot/stage2.map
+ echfs-utils -g -p0 test.hdd import test/test.elf boot/test.elf
+ echfs-utils -g -p0 test.hdd import test/bg.bmp boot/bg.bmp
+ echfs-utils -g -p0 test.hdd import test/font.bin boot/font.bin
./limine-install limine.bin test.hdd
qemu-system-x86_64 -net none -smp 4 -enable-kvm -cpu host -hda test.hdd -debugcon stdio
diff --git a/bootsect/bootsect.asm b/bootsect/bootsect.asm
index 466e4f2f..53d9bc85 100644
--- a/bootsect/bootsect.asm
+++ b/bootsect/bootsect.asm
@@ -54,37 +54,31 @@ start:
; make sure that is the case now.
mov esp, 0x7c00
- push 0x6fe0
+ push 0x7000
pop es
- mov eax, dword [stage2_sector]
+ mov di, stage2_locs
+ mov eax, dword [di]
+ mov ebp, dword [di+4]
xor bx, bx
- mov ecx, 32768
+ xor ecx, ecx
+ mov cx, word [di-4]
+ call read_sectors
+ jc err
+ mov eax, dword [di+8]
+ mov ebp, dword [di+12]
+ add bx, cx
+ mov cx, word [di-2]
call read_sectors
jc err
- call load_gdt
+ lgdt [gdt]
cli
-
mov eax, cr0
bts ax, 0
mov cr0, eax
- jmp 0x18:.mode32
- bits 32
- .mode32:
- mov ax, 0x20
- mov ds, ax
- mov es, ax
- mov fs, ax
- mov gs, ax
- mov ss, ax
-
- and edx, 0xff
-
- jmp vector
-
-bits 16
+ jmp 0x08:vector
err:
hlt
@@ -100,6 +94,15 @@ times 6 db 0
bits 32
vector:
+ mov eax, 0x10
+ mov ds, ax
+ mov es, ax
+ mov fs, ax
+ mov gs, ax
+ mov ss, ax
+
+ and edx, 0xff
+
push 0
push edx
@@ -109,10 +112,12 @@ vector:
call 0x70000
-bits 16
-
-times 0x1b0-($-$$) db 0
-stage2_sector: dd 0
+times 0x1a4-($-$$) db 0
+stage2_size_a: dw 0
+stage2_size_b: dw 0
+stage2_locs:
+stage2_loc_a: dq 0
+stage2_loc_b: dq 0
times 0x1b8-($-$$) db 0
times 510-($-$$) db 0
@@ -127,5 +132,3 @@ align 16
stage2:
incbin '../stage2/stage2.bin.gz'
.size: equ $ - stage2
-
-times 32768-($-$$) db 0
diff --git a/bootsect/disk.inc b/bootsect/disk.inc
index 0886dbef..716cb19b 100644
--- a/bootsect/disk.inc
+++ b/bootsect/disk.inc
@@ -1,9 +1,10 @@
-; ***********************************************
-; Reads a disk sector with an LBA address
-; ***********************************************
+; *****************************
+; Reads bytes from disk
+; *****************************
; IN:
-; EAX = LBA sector to load
+; EAX = Start address to load low 32
+; EBP = Start address to load high 32
; DL = Drive number
; ES = Buffer segment
; BX = Buffer offset
@@ -15,32 +16,47 @@
read_sectors:
pusha
- mov esi, .da_struct
+ mov si, .da_struct
mov word [si], 16
mov word [si+2], 1
mov word [si+4], bx
mov word [si+6], es
- mov dword [si+8], eax
- mov dword [si+12], 0
- ; Get bytes per sector
push dx
push si
+
+ push eax
+ push ebp
+
+ ; Get bytes per sector
mov ah, 0x48
mov si, .drive_params
mov word [si], 30 ; buf_size
int 0x13
jc .done
mov bp, word [si+24] ; bytes_per_sect
+
+ ; ECX byte count to CX sector count
mov ax, cx
shr ecx, 16
mov dx, cx
xor cx, cx
div bp
test dx, dx
- adc cx, ax
+ setnz cl
+ add cx, ax
+
+ pop edx
+ pop eax
+
pop si
+
+ ; EBP:EAX address to EAX LBA sector
+ div ebp
+ mov dword [si+8], eax
+ mov dword [si+12], edx
+
pop dx
.loop:
@@ -52,6 +68,7 @@ read_sectors:
add word [si+4], bp
inc dword [si+8]
+ adc dword [si+12], 0
loop .loop
diff --git a/bootsect/gdt.inc b/bootsect/gdt.inc
index e8735424..6c4c3638 100644
--- a/bootsect/gdt.inc
+++ b/bootsect/gdt.inc
@@ -1,55 +1,8 @@
-%define DIV_ROUNDUP(a, b) (((a) + ((b) - 1)) / (b))
-%define ALIGN_UP(x, a) (DIV_ROUNDUP((x), (a)) * (a))
-
-; The GDT is copied to <start of EBDA> - gdt.size, which will also serve
-; as the upper limit for balloc()
-load_gdt:
- pusha
- push es
- mov ax, word [0x40e] ; 0x40e contains the value of a segment pointing to the EBDA
- sub ax, ALIGN_UP(gdt.size, 16) / 16
- mov es, ax
- mov word [gdt.ptr], ax
- shl dword [gdt.ptr], 4
- xor di, di
- mov si, gdt.start
- mov cx, gdt.size
- rep movsb
- lgdt [gdt]
- pop es
- popa
- ret
-
gdt:
- dw .size - 1 ; GDT size
- .ptr:
- dd 0 ; GDT start address (calculated at runtime)
+ dw .size - 1 + 8 ; GDT size
+ dd .start - 8 ; GDT start address
.start:
- ; Null descriptor (required)
- dw 0x0000 ; Limit
- dw 0x0000 ; Base (low 16 bits)
- db 0x00 ; Base (mid 8 bits)
- db 00000000b ; Access
- db 00000000b ; Granularity
- db 0x00 ; Base (high 8 bits)
-
- ; 16-bit code
- dw 0xffff ; Limit
- dw 0x0000 ; Base (low 16 bits)
- db 0x00 ; Base (mid 8 bits)
- db 10011010b ; Access
- db 00000000b ; Granularity
- db 0x00 ; Base (high 8 bits)
-
- ; 16-bit data
- dw 0xffff ; Limit
- dw 0x0000 ; Base (low 16 bits)
- db 0x00 ; Base (mid 8 bits)
- db 10010010b ; Access
- db 00000000b ; Granularity
- db 0x00 ; Base (high 8 bits)
-
; 32-bit code
dw 0xffff ; Limit
dw 0x0000 ; Base (low 16 bits)
@@ -66,22 +19,6 @@ gdt:
db 11001111b ; Granularity
db 0x00 ; Base (high 8 bits)
- ; 64-bit code
- dw 0x0000 ; Limit
- dw 0x0000 ; Base (low 16 bits)
- db 0x00 ; Base (mid 8 bits)
- db 10011010b ; Access
- db 00100000b ; Granularity
- db 0x00 ; Base (high 8 bits)
-
- ; 64-bit data
- dw 0x0000 ; Limit
- dw 0x0000 ; Base (low 16 bits)
- db 0x00 ; Base (mid 8 bits)
- db 10010010b ; Access
- db 00000000b ; Granularity
- db 0x00 ; Base (high 8 bits)
-
.end:
.size: equ .end - .start
diff --git a/limine-install.c b/limine-install.c
index 9a73c50b..e45c1c0a 100644
--- a/limine-install.c
+++ b/limine-install.c
@@ -2,16 +2,100 @@
#include <stdlib.h>
#include <stdint.h>
#include <stddef.h>
+#include <string.h>
+#include <assert.h>
#include <inttypes.h>
+struct gpt_table_header {
+ // the head
+ char signature[8];
+ uint32_t revision;
+ uint32_t header_size;
+ uint32_t crc32;
+ uint32_t _reserved0;
+
+ // the partitioning info
+ uint64_t my_lba;
+ uint64_t alternate_lba;
+ uint64_t first_usable_lba;
+ uint64_t last_usable_lba;
+
+ // the guid
+ uint64_t disk_guid[2];
+
+ // entries related
+ uint64_t partition_entry_lba;
+ uint32_t number_of_partition_entries;
+ uint32_t size_of_partition_entry;
+ uint32_t partition_entry_array_crc32;
+} __attribute__((packed));
+
+// This table from https://web.mit.edu/freebsd/head/sys/libkern/crc32.c
+const uint32_t crc32_table[] = {
+ 0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f,
+ 0xe963a535, 0x9e6495a3, 0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988,
+ 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91, 0x1db71064, 0x6ab020f2,
+ 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
+ 0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9,
+ 0xfa0f3d63, 0x8d080df5, 0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172,
+ 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b, 0x35b5a8fa, 0x42b2986c,
+ 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
+ 0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423,
+ 0xcfba9599, 0xb8bda50f, 0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924,
+ 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d, 0x76dc4190, 0x01db7106,
+ 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
+ 0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d,
+ 0x91646c97, 0xe6635c01, 0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e,
+ 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457, 0x65b0d9c6, 0x12b7e950,
+ 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
+ 0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7,
+ 0xa4d1c46d, 0xd3d6f4fb, 0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0,
+ 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9, 0x5005713c, 0x270241aa,
+ 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
+ 0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81,
+ 0xb7bd5c3b, 0xc0ba6cad, 0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a,
+ 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683, 0xe3630b12, 0x94643b84,
+ 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
+ 0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb,
+ 0x196c3671, 0x6e6b06e7, 0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc,
+ 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5, 0xd6d6a3e8, 0xa1d1937e,
+ 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
+ 0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55,
+ 0x316e8eef, 0x4669be79, 0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236,
+ 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f, 0xc5ba3bbe, 0xb2bd0b28,
+ 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
+ 0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f,
+ 0x72076785, 0x05005713, 0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38,
+ 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21, 0x86d3d2d4, 0xf1d4e242,
+ 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
+ 0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69,
+ 0x616bffd3, 0x166ccf45, 0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2,
+ 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db, 0xaed16a4a, 0xd9d65adc,
+ 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
+ 0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693,
+ 0x54de5729, 0x23d967bf, 0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94,
+ 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
+};
+
+static uint32_t crc32(void *_stream, size_t len) {
+ uint8_t *stream = _stream;
+ uint32_t ret = 0xffffffff;
+
+ for (size_t i = 0; i < len; i++) {
+ ret = (ret >> 8) ^ crc32_table[(ret ^ stream[i]) & 0xff];
+ }
+
+ ret ^= 0xffffffff;
+ return ret;
+}
+
int main(int argc, char *argv[]) {
FILE *bootloader_file, *device;
uint8_t *bootloader_img;
uint8_t orig_mbr[70], timestamp[6];
- uint32_t stage2_sect, sect_size;
if (argc < 3) {
- printf("Usage: %s <bootloader image> <device> [<stage2 start sector> <sector size>]\n", argv[0]);
+ printf("Usage: %s <bootloader image> <device>\n", argv[0]);
return 1;
}
@@ -21,8 +105,10 @@ int main(int argc, char *argv[]) {
return 1;
}
- // The bootloader image is 64 sectors (32k)
- bootloader_img = malloc(64 * 512);
+ fseek(bootloader_file, 0, SEEK_END);
+ size_t bootloader_file_size = ftell(bootloader_file);
+
+ bootloader_img = malloc(bootloader_file_size);
if (bootloader_img == NULL) {
perror("Error: ");
fclose(bootloader_file);
@@ -31,7 +117,7 @@ int main(int argc, char *argv[]) {
// Load in bootloader image
fseek(bootloader_file, 0, SEEK_SET);
- fread(bootloader_img, 64, 512, bootloader_file);
+ fread(bootloader_img, 1, bootloader_file_size, bootloader_file);
fclose(bootloader_file);
device = fopen(argv[2], "r+b");
@@ -41,12 +127,96 @@ int main(int argc, char *argv[]) {
return 1;
}
- stage2_sect = 0;
- sect_size = 512;
- if (argc >= 4)
- sscanf(argv[3], "%" SCNu32, &stage2_sect);
- if (argc >= 5)
- sscanf(argv[4], "%" SCNu32, §_size);
+ // Probe for GPT and logical block size
+ int gpt = 0;
+ struct gpt_table_header gpt_header;
+ int lb_guesses[] = { 512, 4096 };
+ int lb_size;
+ for (size_t i = 0; i < sizeof(lb_guesses) / sizeof(int); i++) {
+ fseek(device, lb_guesses[i], SEEK_SET);
+ fread(&gpt_header, sizeof(struct gpt_table_header), 1, device);
+ if (!strncmp(gpt_header.signature, "EFI PART", 8)) {
+ gpt = 1;
+ lb_size = lb_guesses[i];
+ fprintf(stderr, "Installing to GPT. Logical block size of %d bytes.\n",
+ lb_guesses[i]);
+ break;
+ }
+ }
+
+ struct gpt_table_header secondary_gpt_header;
+ if (gpt) {
+ fprintf(stderr, "Secondary header at LBA 0x%" PRIx64 ".\n",
+ gpt_header.alternate_lba);
+ fseek(device, lb_size * gpt_header.alternate_lba, SEEK_SET);
+ fread(&secondary_gpt_header, sizeof(struct gpt_table_header), 1, device);
+ if (!strncmp(secondary_gpt_header.signature, "EFI PART", 8)) {
+ fprintf(stderr, "Secondary header valid.\n");
+ } else {
+ fprintf(stderr, "Secondary header not valid, aborting.\n");
+ abort();
+ }
+ }
+
+ size_t stage2_size = bootloader_file_size - 512;
+ uint16_t stage2_size_a = stage2_size / 2 + stage2_size % 2;
+ uint16_t stage2_size_b = stage2_size / 2;
+
+ // Default split of stage2 for MBR (consecutive in post MBR gap)
+ uint64_t stage2_loc_a = 512;
+ uint64_t stage2_loc_b = stage2_loc_a + stage2_size_a;
+ if (stage2_loc_b & 512)
+ stage2_loc_b = (stage2_loc_b + 512) & ~(512 - 1);
+
+ if (gpt) {
+ stage2_loc_a = (gpt_header.partition_entry_lba + 32) * lb_size;
+ stage2_loc_a -= stage2_size_a;
+ stage2_loc_a &= ~(lb_size - 1);
+ stage2_loc_b = (secondary_gpt_header.partition_entry_lba + 32) * lb_size;
+ stage2_loc_b -= stage2_size_b;
+ stage2_loc_b &= ~(lb_size - 1);
+
+ size_t partition_entries_per_lb =
+ lb_size / gpt_header.size_of_partition_entry;
+ size_t new_partition_array_lba_size =
+ stage2_loc_a / lb_size - gpt_header.partition_entry_lba;
+ size_t new_partition_entry_count =
+ new_partition_array_lba_size * partition_entries_per_lb;
+
+ uint8_t *partition_array =
+ malloc(new_partition_entry_count * gpt_header.size_of_partition_entry);
+ assert(partition_array);
+
+ fseek(device, gpt_header.partition_entry_lba * lb_size, SEEK_SET);
+ fread(partition_array,
+ new_partition_entry_count * gpt_header.size_of_partition_entry,
+ 1, device);
+
+ uint32_t crc32_partition_array =
+ crc32(partition_array,
+ new_partition_entry_count * gpt_header.size_of_partition_entry);
+
+ free(partition_array);
+
+ gpt_header.partition_entry_array_crc32 = crc32_partition_array;
+ gpt_header.number_of_partition_entries = new_partition_entry_count;
+ gpt_header.crc32 = 0;
+ gpt_header.crc32 = crc32(&gpt_header, sizeof(struct gpt_table_header));
+ fseek(device, lb_size, SEEK_SET);
+ fwrite(&gpt_header, sizeof(struct gpt_table_header), 1, device);
+
+ secondary_gpt_header.partition_entry_array_crc32 = crc32_partition_array;
+ secondary_gpt_header.number_of_partition_entries =
+ new_partition_entry_count;
+ secondary_gpt_header.crc32 = 0;
+ secondary_gpt_header.crc32 =
+ crc32(&secondary_gpt_header, sizeof(struct gpt_table_header));
+ fseek(device, lb_size * gpt_header.alternate_lba, SEEK_SET);
+ fwrite(&secondary_gpt_header, sizeof(struct gpt_table_header), 1, device);
+ }
+
+ fprintf(stderr, "Stage 2 to be located at 0x%" PRIx64 " and 0x%" PRIx64 ".\n",
+ stage2_loc_a, stage2_loc_b);
// Save original timestamp
fseek(device, 218, SEEK_SET);
@@ -61,12 +231,17 @@ int main(int argc, char *argv[]) {
fwrite(&bootloader_img[0], 1, 512, device);
// Write the rest of stage 2 to the device
- fseek(device, stage2_sect * sect_size, SEEK_SET);
- fwrite(&bootloader_img[0], 64, 512, device);
+ fseek(device, stage2_loc_a, SEEK_SET);
+ fwrite(&bootloader_img[512], 1, stage2_size_a, device);
+ fseek(device, stage2_loc_b, SEEK_SET);
+ fwrite(&bootloader_img[512 + stage2_size_a], 1, stage2_size_b, device);
- // Hardcode in the bootsector the location of stage 2
- fseek(device, 0x1b0, SEEK_SET);
- fwrite(&stage2_sect, 1, sizeof(uint32_t), device);
+ // Hardcode in the bootsector the location of stage 2 halves
+ fseek(device, 0x1a4, SEEK_SET);
+ fwrite(&stage2_size_a, 1, sizeof(uint16_t), device);
+ fwrite(&stage2_size_b, 1, sizeof(uint16_t), device);
+ fwrite(&stage2_loc_a, 1, sizeof(uint64_t), device);
+ fwrite(&stage2_loc_b, 1, sizeof(uint64_t), device);
// Write back timestamp
fseek(device, 218, SEEK_SET);
diff --git a/limine-pxe.bin b/limine-pxe.bin
index 6f7b527b..7104431f 100644
Binary files a/limine-pxe.bin and b/limine-pxe.bin differ
diff --git a/limine.bin b/limine.bin
index c9ea74c2..60383bde 100644
Binary files a/limine.bin and b/limine.bin differ
diff --git a/pxeboot/bootsect.asm b/pxeboot/bootsect.asm
index a082d441..ad033ef5 100644
--- a/pxeboot/bootsect.asm
+++ b/pxeboot/bootsect.asm
@@ -10,7 +10,7 @@ start:
mov ss, ax
mov sp, 0x7c00
sti
- call load_gdt
+ lgdt [gdt]
cli
@@ -18,10 +18,10 @@ start:
bts ax, 0
mov cr0, eax
- jmp 0x18:.mode32
+ jmp 0x08:.mode32
bits 32
.mode32:
- mov ax, 0x20
+ mov ax, 0x10
mov ds, ax
mov es, ax
mov fs, ax
diff --git a/stage2.map b/stage2.map
index 6405917a..68d4efb5 100644
Binary files a/stage2.map and b/stage2.map differ
diff --git a/stage2/entry.asm b/stage2/entry.asm
index c2b94a97..d7503160 100644
--- a/stage2/entry.asm
+++ b/stage2/entry.asm
@@ -1,6 +1,7 @@
extern bss_begin
extern bss_end
extern entry
+extern gdt
section .entry
@@ -15,4 +16,14 @@ _start:
sub ecx, bss_begin
rep stosb
+ lgdt [gdt]
+ jmp 0x18:.reload_cs
+ .reload_cs:
+ mov eax, 0x20
+ mov ds, ax
+ mov es, ax
+ mov fs, ax
+ mov gs, ax
+ mov ss, ax
+
jmp entry
diff --git a/stage2/lib/part.c b/stage2/lib/part.c
index b8d326ed..d54054a4 100644
--- a/stage2/lib/part.c
+++ b/stage2/lib/part.c
@@ -199,7 +199,7 @@ load_up:
if (part_index)
return;
- part_index = conv_mem_alloc(sizeof(struct part) * part_count);
+ part_index = ext_mem_alloc(sizeof(struct part) * part_count);
goto load_up;
}
}
diff --git a/stage2/main.c b/stage2/main.c
index 25d0ebe1..c741f7f3 100644
--- a/stage2/main.c
+++ b/stage2/main.c
@@ -33,10 +33,11 @@ void entry(uint8_t _boot_drive, int pxe_boot) {
if (!a20_enable())
panic("Could not enable A20 line");
- part_create_index();
init_e820();
init_memmap();
+ part_create_index();
+
if (pxe_boot) {
pxe_init();
if(init_config_pxe()) {
diff --git a/stage2/mm/pmm.c b/stage2/mm/pmm.c
index b0e83565..530ef8d5 100644
--- a/stage2/mm/pmm.c
+++ b/stage2/mm/pmm.c
@@ -293,13 +293,8 @@ void *conv_mem_alloc(size_t count) {
void *conv_mem_alloc_aligned(size_t count, size_t alignment) {
if (!bump_allocator_limit) {
- // The balloc limit is the beginning of the GDT
- struct {
- uint16_t limit;
- uint32_t ptr;
- } __attribute__((packed)) gdtr;
- asm volatile ("sgdt %0" :: "m"(gdtr) : "memory");
- bump_allocator_limit = gdtr.ptr;
+ // The balloc limit is the beginning of the EBDA
+ bump_allocator_limit = *((uint16_t *)0x40e) << 4;
}
size_t new_base = ALIGN_UP(bump_allocator_base, alignment);
diff --git a/stage2/sys/gdt.asm b/stage2/sys/gdt.asm
new file mode 100644
index 00000000..b9f450c5
--- /dev/null
+++ b/stage2/sys/gdt.asm
@@ -0,0 +1,63 @@
+section .data
+
+global gdt
+
+gdt:
+ dw .size - 1 ; GDT size
+ dd .start ; GDT start address
+
+ .start:
+ ; Null desc
+ dq 0
+
+ ; 16-bit code
+ dw 0xffff ; Limit
+ dw 0x0000 ; Base (low 16 bits)
+ db 0x00 ; Base (mid 8 bits)
+ db 10011010b ; Access
+ db 00000000b ; Granularity
+ db 0x00 ; Base (high 8 bits)
+
+ ; 16-bit data
+ dw 0xffff ; Limit
+ dw 0x0000 ; Base (low 16 bits)
+ db 0x00 ; Base (mid 8 bits)
+ db 10010010b ; Access
+ db 00000000b ; Granularity
+ db 0x00 ; Base (high 8 bits)
+
+ ; 32-bit code
+ dw 0xffff ; Limit
+ dw 0x0000 ; Base (low 16 bits)
+ db 0x00 ; Base (mid 8 bits)
+ db 10011010b ; Access
+ db 11001111b ; Granularity
+ db 0x00 ; Base (high 8 bits)
+
+ ; 32-bit data
+ dw 0xffff ; Limit
+ dw 0x0000 ; Base (low 16 bits)
+ db 0x00 ; Base (mid 8 bits)
+ db 10010010b ; Access
+ db 11001111b ; Granularity
+ db 0x00 ; Base (high 8 bits)
+
+ ; 64-bit code
+ dw 0x0000 ; Limit
+ dw 0x0000 ; Base (low 16 bits)
+ db 0x00 ; Base (mid 8 bits)
+ db 10011010b ; Access
+ db 00100000b ; Granularity
+ db 0x00 ; Base (high 8 bits)
+
+ ; 64-bit data
+ dw 0x0000 ; Limit
+ dw 0x0000 ; Base (low 16 bits)
+ db 0x00 ; Base (mid 8 bits)
+ db 10010010b ; Access
+ db 00000000b ; Granularity
+ db 0x00 ; Base (high 8 bits)
+
+ .end:
+
+ .size: equ .end - .start
