ChangeLog:
* boot/i386/pc/boot.S: Declare 0x0-0x7c00 as a discardable .bss
segment. Eliminate ABS, rely on the assembler knowing correct
addresses. Eliminate .bss segment for the kernel, use direct
jump to the kernel address.
---
boot/i386/pc/boot.S | 72 +++++++++------------------------------------------
1 files changed, 12 insertions(+), 60 deletions(-)
diff --git a/boot/i386/pc/boot.S b/boot/i386/pc/boot.S
index e3f5228..0002773 100644
--- a/boot/i386/pc/boot.S
+++ b/boot/i386/pc/boot.S
@@ -24,20 +24,13 @@
* defines for the code go here
*/
- /* Absolute addresses
- This makes the assembler generate the address without support
- from the linker. (ELF can't relocate 16-bit addresses!) */
-#define ABS(x) (x-_start+0x7c00)
-
/* Print message string */
-#ifdef APPLE_CC
-#define MSG(x) x ## _abs = ABS(x); movw $x ## _abs, %si; call message
-#else
-#define MSG(x) movw $ABS(x), %si; call message
-#endif
+#define MSG(x) movw $x, %si; call message
.file "boot.S"
+ .bss
+ . = 0x7c00
.text
/* Tell GAS to generate 16-bit instructions so that this code works
@@ -126,12 +119,7 @@ boot_drive_check:
* ljmp to the next instruction because some bogus BIOSes
* jump to 07C0:0000 instead of 0000:7C00.
*/
-#ifdef APPLE_CC
- real_start_abs = ABS(real_start)
- ljmp $0, $(real_start_abs)
-#else
- ljmp $0, $ABS(real_start)
-#endif
+ ljmp $0, $real_start
real_start:
@@ -148,12 +136,7 @@ real_start:
/*
* Check if we have a forced disk reference here
*/
-#ifdef APPLE_CC
- boot_drive_abs = ABS (boot_drive)
- movb boot_drive_abs, %al
-#else
- movb ABS(boot_drive), %al
-#endif
+ movb boot_drive, %al
cmpb $0xff, %al
je 1f
movb %al, %dl
@@ -165,12 +148,7 @@ real_start:
MSG(notification_string)
/* set %si to the disk address packet */
-#ifdef APPLE_CC
- disk_address_packet_abs = ABS (disk_address_packet)
- movw $disk_address_packet_abs, %si
-#else
- movw $ABS(disk_address_packet), %si
-#endif
+ movw $disk_address_packet, %si
/* do not probe LBA if the drive is a floppy */
testb $GRUB_BOOT_MACHINE_BIOS_HD_FLAG, %dl
@@ -211,18 +189,10 @@ lba_mode:
movw $0x0010, (%si)
/* the absolute address */
-#ifdef APPLE_CC
- kernel_sector_abs = ABS (kernel_sector)
- movl (kernel_sector_abs), %ebx
- movl %ebx, 8(%si)
- movl (kernel_sector_abs + 4), %ebx
- movl %ebx, 12(%si)
-#else
- movl ABS(kernel_sector), %ebx
+ movl kernel_sector, %ebx
movl %ebx, 8(%si)
- movl ABS(kernel_sector + 4), %ebx
+ movl kernel_sector + 4, %ebx
movl %ebx, 12(%si)
-#endif
/* the segment of buffer address */
movw $GRUB_BOOT_MACHINE_BUFFER_SEG, 6(%si)
@@ -289,22 +259,13 @@ final_init:
setup_sectors:
/* load logical sector start (top half) */
-#ifdef APPLE_CC
- kernel_sector_abs = ABS (kernel_sector)
- movl (kernel_sector_abs + 4), %eax
-#else
- movl ABS(kernel_sector + 4), %eax
-#endif
+ movl kernel_sector + 4, %eax
orl %eax, %eax
jnz geometry_error
/* load logical sector start (bottom half) */
-#ifdef APPLE_CC
- movl (kernel_sector_abs), %eax
-#else
- movl ABS(kernel_sector), %eax
-#endif
+ movl kernel_sector, %eax
/* zero %edx */
xorl %edx, %edx
@@ -389,7 +350,7 @@ copy_buffer:
popa
/* boot kernel */
- jmp kernel_entry
+ jmp GRUB_BOOT_MACHINE_KERNEL_ADDR
/* END OF MAIN LOOP */
@@ -475,12 +436,7 @@ floppy_probe:
* Perform floppy probe.
*/
-#ifdef APPLE_CC
- probe_values_abs = ABS (probe_values)
- movw $(probe_values_abs-1), %si
-#else
- movw $ABS(probe_values-1), %si
-#endif
+ movw $probe_values - 1, %si
probe_loop:
/* reset floppy controller INT 13h AH=0 */
@@ -524,7 +480,3 @@ fd_probe_error_string: .asciz "Floppy"
/* the last 2 bytes in the sector 0 contain the signature */
.word GRUB_BOOT_MACHINE_SIGNATURE
-
- .bss
- . = . + 0x200
-kernel_entry:
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