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| author | Michael Brown | 2012-07-09 21:37:09 +0200 |
|---|---|---|
| committer | Michael Brown | 2015-04-20 22:30:12 +0200 |
| commit | e34a3cd87a2654071b14bd8ae97d7cb8841be852 (patch) | |
| tree | 1ca33779218f6b463335fd47ccaedfbc08f3df15 | |
| parent | [setup] Revert unused SMP code (diff) | |
| download | memtest86-e34a3cd87a2654071b14bd8ae97d7cb8841be852.tar.gz memtest86-e34a3cd87a2654071b14bd8ae97d7cb8841be852.tar.xz memtest86-e34a3cd87a2654071b14bd8ae97d7cb8841be852.zip | |
[setup] Make setup.S position-independent code
Derive the base address of the GDT from %cs, in order to allow setup.S
to be loaded to any address.
Signed-off-by: Michael Brown <mcb30@ipxe.org>
| -rw-r--r-- | setup.S | 9 |
1 files changed, 6 insertions, 3 deletions
@@ -22,8 +22,11 @@ start: outb %al, $0x70 # The system will move itself to its rightful place. - push %cs - pop %ds + xorl %eax, %eax + movw %cs, %ax + movw %ax, %ds + shll $4, %eax + addl %eax, gdt_48 - start + 2 lidt idt_48 - start # load idt with 0,0 lgdt gdt_48 - start # load gdt with whatever appropriate @@ -134,7 +137,7 @@ idt_48: gdt_48: .word 0x800 # gdt limit=2048, 256 GDT entries - .word 512+gdt - start,0x9 # gdt base = 0X9xxxx + .long gdt - start # gdt base msg1: .asciz "Setup.S\r\n" |