extboot is an x86 Option ROM that passes through int13 functions to a VMM which
allows a VMM to expose an arbitrary block device as the primary BIOS disk. It
can be used to boot SCSI or paravirtual devices.
Signed-off-by: Anthony Liguori <[EMAIL PROTECTED]>
diff --git a/extboot/Makefile b/extboot/Makefile
new file mode 100644
index 0000000..1ea71a7
--- /dev/null
+++ b/extboot/Makefile
@@ -0,0 +1,21 @@
+OBJCOPY=objcopy
+
+CFLAGS=-Wall -Wstrict-prototypes -Werror -fomit-frame-pointer -fno-builtin \
+ -fno-stack-protector
+
+all: extboot.bin
+
+%.o: %.S
+ $(CC) $(CFLAGS) -o $@ -c $<
+
+extboot.img: extboot.o
+ $(LD) --oformat binary -Ttext 0 -o $@ $<
+
+extboot.bin: extboot.img signrom
+ ./signrom extboot.img extboot.bin
+
+signrom: signrom.c
+ $(CC) -o $@ -g -Wall $^
+
+clean:
+ $(RM) *.o *.img *.bin signrom *~
diff --git a/extboot/STATUS b/extboot/STATUS
new file mode 100644
index 0000000..687c6d6
--- /dev/null
+++ b/extboot/STATUS
@@ -0,0 +1,6 @@
+Working
+-------
+
+Ubuntu Server 7.04 (i386)
+Windows 2000 Professional (i386)
+Windows XP SP2 (i386)
diff --git a/extboot/extboot.S b/extboot/extboot.S
new file mode 100644
index 0000000..7b6e9b2
--- /dev/null
+++ b/extboot/extboot.S
@@ -0,0 +1,742 @@
+/*
+ * Extended Boot Option ROM
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright IBM Corporation, 2007
+ * Authors: Anthony Liguori <[EMAIL PROTECTED]>
+ */
+
+.code16
+.text
+ .global _start
+_start:
+ .short 0xaa55
+ .byte (_end - _start) / 512
+ push %ax
+ push %bx
+ push %cx
+ push %dx
+ push %ds
+
+ /* setup ds so we can access the IVT */
+ xor %ax, %ax
+ mov %ax, %ds
+
+ /* save old int 19 at int 2b */
+ mov $(0x19 * 4), %bx
+ mov 0(%bx), %ax
+ mov 2(%bx), %cx
+
+ mov $(0x2b * 4), %bx
+ mov %ax, 0(%bx)
+ mov %cx, 2(%bx)
+
+ /* install out int 19 handler */
+ mov $(0x19 * 4), %bx
+ mov $int19_handler, %ax
+ mov %ax, 0(%bx)
+ mov %cs, 2(%bx)
+
+ pop %ds
+ pop %dx
+ pop %cx
+ pop %bx
+ pop %ax
+ lret
+
+int19_handler:
+ push %ax
+ push %bx
+ push %cx
+ push %dx
+ push %ds
+
+ movw $0x404, %dx
+ inb %dx, %al
+ cmp $1, %al
+ je 1f
+ cmp $2, %al
+ je 2f
+ jmp 3f
+
+1: /* hook int13: intb(0x404) == 1 */
+ /* setup ds to access IVT */
+ xor %ax, %ax
+ mov %ax, %ds
+
+ /* save old int 13 to int 2c */
+ mov $(0x13 * 4), %bx
+ mov 0(%bx), %ax
+ mov 2(%bx), %cx
+
+ mov $(0x2c * 4), %bx
+ mov %ax, 0(%bx)
+ mov %cx, 2(%bx)
+
+ /* install our int 13 handler */
+ mov $(0x13 * 4), %bx
+ mov $int13_handler, %ax
+
+ mov %ax, 0(%bx)
+ mov %cs, 2(%bx)
+ jmp 3f
+
+2: /* linux boot: intb(0x404) == 2 */
+ cli
+ cld
+ mov $0x9000, %ax
+ mov %ax, %ds
+ mov %ax, %es
+ mov %ax, %fs
+ mov %ax, %gs
+ mov %ax, %ss
+ mov $0x8ffe, %sp
+ ljmp $0x9000 + 0x20, $0
+
+3: /* fall through: inb(0x404) == 0 */
+ pop %ds
+ pop %dx
+ pop %cx
+ pop %bx
+ pop %ax
+ int $0x2b
+
+#define FLAGS_CF 0x01
+
+.macro clc
+ push %ax
+ pushf
+ pop %ax
+ and $(~FLAGS_CF), %ax
+ push %ax
+ popf
+ pop %ax
+.endm
+
+.macro stc
+ push %ax
+ pushf
+ pop %ax
+ or $(FLAGS_CF), %ax
+ push %ax
+ popf
+ pop %ax
+.endm
+
+/* we clobber %bx */
+.macro alloca size
+ push %ds
+ push %bp
+ mov %sp, %bp /* remember the current stack position */
+
+ mov %ss, %bx
+ mov %bx, %ds
+
+ sub \size, %sp
+ and $(~0x0F), %sp
+ mov %sp, %bx
+
+ push %bp
+ mov 0(%bp), %bp
+.endm
+
+/* we clobber %bp */
+.macro allocbpa size
+ mov %sp, %bp /* remember the current stack position */
+ sub \size, %sp
+ and $(~0x0F), %sp
+ push %bp
+ mov %sp, %bp
+ add $2, %bp
+.endm
+
+.macro freea
+ pop %sp
+ add $2, %sp
+ pop %ds
+.endm
+
+.macro freebpa
+ pop %sp
+.endm
+
+.macro dump reg
+ push %ax
+ push %dx
+
+ mov \reg, %ax
+ mov $0x406, %dx
+ outw %ax, %dx
+
+ pop %dx
+ pop %ax
+.endm
+
+.macro callout value
+ push %bp
+ push %bx
+ mov %sp, %bp
+ alloca $16
+ push %ax
+ push %dx
+
+ mov %ax, 0(%bx) /* ax */
+ mov 0(%bp), %ax /* bx */
+ mov %ax, 2(%bx)
+ mov %cx, 4(%bx) /* cx */
+ mov %dx, 6(%bx) /* dx */
+ mov %si, 8(%bx) /* si */
+ mov %ds, 10(%bx) /* ds */
+ mov %es, 12(%bx) /* ds */
+ movw \value, 14(%bx) /* value */
+
+ mov %bx, %ax
+ shr $4, %ax
+ mov %ds, %dx
+ add %dx, %ax
+
+ mov $0x407, %dx
+ outw %ax, %dx
+
+ pop %dx
+ pop %ax
+ freea
+ pop %bx
+ pop %bp
+.endm
+
+send_command:
+ push %bp
+ mov %sp, %bp
+ push %ax
+ push %bx
+ push %dx
+
+ mov 4(%bp), %ax
+ shr $4, %ax
+ and $0x0FFF, %ax
+ mov %ss, %bx
+ add %bx, %ax
+
+ mov $0x405, %dx
+ outw %ax, %dx
+
+ pop %dx
+ pop %bx
+ pop %ax
+ pop %bp
+
+ push %ax
+ mov 2(%bx), %ax
+ pop %ax
+
+ ret
+
+add32: /* lo, hi, lo, hi */
+ push %bp
+ mov %sp, %bp
+
+ movw 4(%bp), %cx /* hi */
+ movw 6(%bp), %dx /* lo */
+
+ add 10(%bp), %dx
+ jnc 1f
+ add $1, %cx
+1: add 8(%bp), %cx
+
+ pop %bp
+ ret
+
+mul32: /* lo, hi, lo, hi */
+ /* 10(%bp), 8(%bp), 6(%bp), 4(%bp) */
+ push %bp
+ mov %sp, %bp
+ push %ax
+ push %bx
+
+ xor %cx, %cx
+ xor %dx, %dx
+
+ /* for (i = 0; i < 16;) */
+ xor %bx, %bx
+0:
+ cmp $16, %bx
+ jge 2f
+
+ mov 6(%bp), %ax
+ and $1, %ax
+ cmp $1, %ax
+ jne 1f
+ push 10(%bp)
+ push 8(%bp)
+ push %dx
+ push %cx
+ call add32
+ add $8, %sp
+1:
+ shlw $1, 8(%bp)
+ movw 10(%bp), %ax
+ and $0x8000, %ax
+ cmp $0x8000, %ax
+ jne 1f
+ orw $1, 8(%bp)
+1:
+ shlw $1, 10(%bp)
+ shrw $1, 6(%bp)
+
+ /* i++) { */
+ add $1, %bx
+ jmp 0b
+
+2:
+ pop %bx
+ pop %ax
+ pop %bp
+ ret
+
+disk_reset:
+ movb $0, %ah
+ clc
+ ret
+
+/* this really should be a function, not a macro but i'm lazy */
+.macro read_write_disk_sectors cmd
+ push %ax
+ push %bx
+ push %cx
+ push %dx
+ push %si
+
+ push %bp
+ sub $10, %sp
+ mov %sp, %bp
+
+ /* save nb_sectors */
+ mov %al, 6(%bp)
+ movb $0, 7(%bp)
+
+ /* save buffer */
+ mov %bx, 8(%bp)
+
+ /* cylinders */
+ xor %ax, %ax
+ mov %cl, %al
+ shl $2, %ax
+ and $0x300, %ax
+ mov %ch, %al
+ mov %ax, 0(%bp)
+
+ /* heads */
+ xor %ax, %ax
+ mov %dh, %al
+ mov %ax, 2(%bp)
+
+ /* sectors - 1 */
+ xor %ax, %ax
+ mov %cl, %al
+ and $0x3F, %al
+ sub $1, %ax
+ mov %ax, 4(%bp)
+
+ alloca $8
+
+ movw $0, 0(%bx) /* read c,h,s */
+ push %bx
+ call send_command
+ add $2, %sp
+
+ mov 6(%bx), %ax /* total_sectors */
+ mov 2(%bp), %si /* *= heads */
+ mul %si
+ add 4(%bp), %ax /* += sectors - 1 */
+
+ push 4(%bx) /* total_heads */
+ push $0
+ push 6(%bx) /* total_sectors */
+ push $0
+ call mul32
+ add $8, %sp
+
+ push 0(%bp) /* cylinders */
+ push $0
+ push %dx
+ push %cx
+ call mul32
+ add $8, %sp
+
+ add %ax, %dx
+ jnc 1f
+ add $1, %cx
+1:
+ freea
+
+ alloca $16
+
+ movw \cmd, 0(%bx) /* read */
+ movw 6(%bp), %ax /* nb_sectors */
+ movw %ax, 2(%bx)
+ movw %es, 4(%bx) /* segment */
+ movw 8(%bp), %ax /* offset */
+ mov %ax, 6(%bx)
+ movw %dx, 8(%bx) /* sector */
+ movw %cx, 10(%bx)
+ movw $0, 12(%bx)
+ movw $0, 14(%bx)
+
+ push %bx
+ call send_command
+ add $2, %sp
+
+ freea
+
+ add $10, %sp
+ pop %bp
+
+ pop %si
+ pop %dx
+ pop %cx
+ pop %bx
+ pop %ax
+
+ mov $0, %ah
+ clc
+ ret
+.endm
+
+read_disk_sectors:
+ read_write_disk_sectors $0x01
+
+write_disk_sectors:
+ read_write_disk_sectors $0x02
+
+read_disk_drive_parameters:
+ push %bx
+
+ /* allocate memory for packet, pointer gets returned in bx */
+ alloca $8
+
+ /* issue command */
+ movw $0, 0(%bx) /* cmd = 0, read c,h,s */
+ push %bx
+ call send_command
+ add $2, %sp
+
+ /* normalize sector value */
+ movb 6(%bx), %cl
+ andb $0x3F, %cl
+ movb %cl, 6(%bx)
+
+ /* normalize cylinders */
+ subw $2, 2(%bx)
+
+ /* normalize heads */
+ subw $1, 4(%bx)
+
+ /* return code */
+ mov $0, %ah
+
+ /* cylinders */
+ movb 2(%bx), %ch
+ movb 3(%bx), %cl
+ shlb $6, %cl
+ andb $0xC0, %cl
+
+ /* sectors */
+ orb 6(%bx), %cl
+
+ /* heads */
+ movb 4(%bx), %dh
+
+ /* drives */
+ movb $1, %dl
+
+ /* status */
+ mov $0, %ah
+
+ freea
+
+ pop %bx
+
+ /* do this last since it's the most sensitive */
+ clc
+ ret
+
+alternate_disk_reset:
+ movb $0, %ah
+ clc
+ ret
+
+read_disk_drive_size:
+ push %bx
+ alloca $8
+
+ movw $0, 0(%bx) /* cmd = 0, read c,h,s */
+ push %bx
+ call send_command
+ add $2, %sp
+
+ /* cylinders - 1 to cx:dx */
+ mov 2(%bx), %dx
+ xor %cx, %cx
+ sub $1, %dx
+
+ /* heads */
+ push 4(%bx)
+ push $0
+ push %dx
+ push %cx
+ call mul32
+ add $8, %sp
+
+ /* sectors */
+ push 6(%bx)
+ push $0
+ push %dx
+ push %cx
+ call mul32
+ add $8, %sp
+
+ /* status */
+ mov $3, %ah
+
+ freea
+ pop %bx
+
+ clc
+ ret
+
+check_if_extensions_present:
+ mov $0x30, %ah
+ mov $0xAA55, %bx
+ mov $0x07, %cx
+ clc
+ ret
+
+.macro extended_read_write_sectors cmd
+ cmpb $10, 0(%si)
+ jg 1f
+ mov $1, %ah
+ stc
+ ret
+1:
+ push %ax
+ push %bp
+ allocbpa $16
+
+ movw \cmd, 0(%bp) /* read */
+ movw 2(%si), %ax /* nb_sectors */
+ movw %ax, 2(%bp)
+ movw 4(%si), %ax /* offset */
+ movw %ax, 6(%bp)
+ movw 6(%si), %ax /* segment */
+ movw %ax, 4(%bp)
+ movw 8(%si), %ax /* block */
+ movw %ax, 8(%bp)
+ movw 10(%si), %ax
+ movw %ax, 10(%bp)
+ movw 12(%si), %ax
+ movw %ax, 12(%bp)
+ movw 14(%si), %ax
+ movw %ax, 14(%bp)
+
+ push %bp
+ call send_command
+ add $2, %sp
+
+ freebpa
+ pop %bp
+ pop %ax
+
+ mov $0, %ah
+ clc
+ ret
+.endm
+
+extended_read_sectors:
+ extended_read_write_sectors $0x01
+
+extended_write_sectors:
+ extended_read_write_sectors $0x02
+
+get_extended_drive_parameters:
+ mov $1, %ah
+ stc
+ ret
+#if 0
+ /* this function is seriously borked */
+1:
+ push %ax
+ push %bp
+ push %cx
+ push %dx
+
+ allocbpa $8
+
+ movw $0, 0(%bp) /* read c,h,s */
+ push %bp
+ call send_command
+ add $2, %sp
+
+ /* check the size of the passed in data */
+ cmpw $26, 0(%si)
+ mov 0(%si), %ax
+ dump %ax
+ jle 0b
+
+ /* set flags to 2 */
+ movw $2, 2(%si)
+
+ /* cylinders */
+ mov 2(%bp), %ax
+ mov %ax, 4(%si)
+ xor %ax, %ax
+ mov %ax, 6(%si)
+
+ /* heads */
+ mov 4(%bp), %ax
+ mov %ax, 8(%si)
+ xor %ax, %ax
+ mov %ax, 10(%si)
+
+ /* sectors */
+ mov 6(%bp), %ax
+ mov %ax, 12(%si)
+ xor %ax, %ax
+ mov %ax, 14(%si)
+
+ /* calculate total sectors */
+
+ /* cx:dx = cylinders */
+ mov 2(%bp), %dx
+ xor %cx, %cx
+
+ /* *= heads */
+ push 4(%bp)
+ push $0
+ push %dx
+ push %cx
+ call mul32
+ add $8, %sp
+
+ /* *= sectors */
+ push 6(%bp)
+ push $0
+ push %dx
+ push %cx
+ call mul32
+ add $8, %sp
+
+ /* total number of sectors */
+ mov %dx, 16(%si)
+ mov %cx, 18(%si)
+ xor %ax, %ax
+ mov %ax, 20(%si)
+ mov %ax, 22(%si)
+
+ /* number of bytes per sector */
+ movw $512, 24(%si)
+
+ /* optional segmention:offset to EDD config */
+ cmpw $30, 0(%si)
+ jl 1f
+
+ movw $0xFFFF, 26(%si)
+ movw $0xFFFF, 28(%si)
+
+1:
+ freebpa
+
+ pop %dx
+ pop %cx
+ pop %bp
+ pop %ax
+
+ mov $0, %ah
+ clc
+ ret
+#endif
+
+terminate_disk_emulation:
+ mov $1, %ah
+ stc
+ ret
+
+int13_handler:
+ cmp $0x80, %dl
+ je 1f
+ int $0x2c
+ iret
+1:
+ cmp $0x0, %ah
+ jne 1f
+ call disk_reset
+ iret
+1:
+ cmp $0x2, %ah
+ jne 1f
+ call read_disk_sectors
+ iret
+1:
+ cmp $0x8, %ah
+ jne 1f
+ call read_disk_drive_parameters
+ iret
+1:
+ cmp $0x15, %ah
+ jne 1f
+ call read_disk_drive_size
+ iret
+1:
+ cmp $0x41, %ah
+ jne 1f
+ call check_if_extensions_present
+ iret
+1:
+ cmp $0x42, %ah
+ jne 1f
+ call extended_read_sectors
+ iret
+1:
+ cmp $0x48, %ah
+ jne 1f
+ call get_extended_drive_parameters
+ iret
+1:
+ cmp $0x4b, %ah
+ jne 1f
+ call terminate_disk_emulation
+ iret
+1:
+ cmp $0x0d, %ah
+ jne 1f
+ call alternate_disk_reset
+ iret
+1:
+ cmp $0x03, %ah
+ jne 1f
+ call write_disk_sectors
+ iret
+1:
+ cmp $0x43, %ah
+ jne 1f
+ call extended_write_sectors
+ iret
+1:
+ int $0x18 /* boot failed */
+ iret
+
+.align 512, 0
+_end:
diff --git a/extboot/signrom.c b/extboot/signrom.c
new file mode 100644
index 0000000..fe8d677
--- /dev/null
+++ b/extboot/signrom.c
@@ -0,0 +1,79 @@
+/*
+ * Extended Boot Option ROM
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Copyright IBM Corporation, 2007
+ * Authors: Anthony Liguori <[EMAIL PROTECTED]>
+ */
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+
+int main(int argc, char **argv)
+{
+ FILE *fin, *fout;
+ char buffer[512], oldbuffer[512];
+ int i, size, lag = 0;
+ uint8_t sum = 0;
+
+ if (argc != 3) {
+ printf("Usage: %s ROM OUTPUT\n", argv[0]);
+ return 1;
+ }
+
+ fin = fopen(argv[1], "rb");
+ fout = fopen(argv[2], "wb");
+
+ if (fin == NULL || fout == NULL) {
+ fprintf(stderr, "Could not open input/output files\n");
+ return 1;
+ }
+
+ do {
+ size = fread(buffer, 512, 1, fin);
+ if (size == 1) {
+ for (i = 0; i < 512; i++)
+ sum += buffer[i];
+
+ if (lag) {
+ if (fwrite(oldbuffer, 512, 1, fout) != 1) {
+ fprintf(stderr, "Write failed\n");
+ return 1;
+ }
+ }
+ lag = 1;
+ memcpy(oldbuffer, buffer, 512);
+ }
+ } while (size == 1);
+
+ if (size != 0) {
+ fprintf(stderr, "Failed to read from input file\n");
+ return 1;
+ }
+
+ oldbuffer[511] = -sum;
+
+ if (fwrite(oldbuffer, 512, 1, fout) != 1) {
+ fprintf(stderr, "Failed to write to output file\n");
+ return 1;
+ }
+
+ fclose(fin);
+ fclose(fout);
+
+ return 0;
+}
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