Messages in this thread Patch in this message | | | Date | Sun, 4 Nov 2007 14:57:50 -0800 | From | "H. Peter Anvin" <> | Subject | [GIT PULL] x86 setup: correct booting on 486DX4 |
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Hi Linus; please pull:
git://git.kernel.org/pub/scm/linux/kernel/git/hpa/linux-2.6-x86setup.git for-linus
H. Peter Anvin (1): x86 setup: correct booting on 486DX4
arch/x86/boot/pmjump.S | 32 +++++++++++++++++++++----------- 1 files changed, 21 insertions(+), 11 deletions(-)
[Full diff and log follows]
commit ac3b37b78c5f0f0be0b476a35370650f7bad482f Author: H. Peter Anvin <hpa@zytor.com> Date: Sun Nov 4 14:33:41 2007 -0800
x86 setup: correct booting on 486DX4 Apparently, the 486DX4 does not correctly serialize a mov to %cr0, so we really do need the far jump immediately afterwards. This means losing the nice separation between 16- and 32-bit code, but c'est la vie. Also pass %ebx = %edi = %ebp = 0 to support future extension of the 32-bit boot protocol. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
diff --git a/arch/x86/boot/pmjump.S b/arch/x86/boot/pmjump.S index 2e55923..17e6dec 100644 --- a/arch/x86/boot/pmjump.S +++ b/arch/x86/boot/pmjump.S @@ -28,27 +28,37 @@ * void protected_mode_jump(u32 entrypoint, u32 bootparams); */ protected_mode_jump: - xorl %ebx, %ebx # Flag to indicate this is a boot movl %edx, %esi # Pointer to boot_params table - movl %eax, 2f # Patch ljmpl instruction + + xorl %edx, %edx + movw %cs, %dx + shll $4, %edx # Patch ljmpl instruction + addl %edx, 2f jmp 1f # Short jump to flush instruction q. 1: movw $__BOOT_DS, %cx + xorl %ebx, %ebx # Per protocol + xorl %ebp, %ebp # Per protocol + xorl %edi, %edi # Per protocol movl %cr0, %edx orb $1, %dl # Protected mode (PE) bit movl %edx, %cr0 + + .byte 0x66, 0xea # ljmpl opcode +2: .long 3f # Offset + .word __BOOT_CS # Segment - movw %cx, %ds - movw %cx, %es - movw %cx, %fs - movw %cx, %gs - movw %cx, %ss + .code32 +3: + movl %ecx, %ds + movl %ecx, %es + movl %ecx, %fs + movl %ecx, %gs + movl %ecx, %ss # Jump to the 32-bit entrypoint - .byte 0x66, 0xea # ljmpl opcode -2: .long 0 # offset - .word __BOOT_CS # segment - + jmpl *%eax + .size protected_mode_jump, .-protected_mode_jump - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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