aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorH. Peter Anvin <hpa@zytor.com>2007-11-04 17:54:31 -0800
committerH. Peter Anvin <hpa@zytor.com>2007-11-04 19:48:04 -0800
commit9f259cc59ba45b8db401d60be9700e275676fb15 (patch)
treedc57ec27c11c98fbb2ed4448d13030c4fc0b6cca
parent7ed192906a2144ebc8ca2925a85d27b9c5355668 (diff)
x86 setup: set %ebx == %ebp == %edi == 0 on protected mode entry
In accordance with the newly formalized 32-bit boot protocol, set %ebx == %ebp == %edi == 0 in order to support future extensions to the protocol. Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--arch/x86/boot/pmjump.S4
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/boot/pmjump.S b/arch/x86/boot/pmjump.S
index 26baeab3a4d..fa6bed1fac1 100644
--- a/arch/x86/boot/pmjump.S
+++ b/arch/x86/boot/pmjump.S
@@ -28,11 +28,13 @@
* 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
movw $__BOOT_DS, %cx
+ xorl %ebx, %ebx # Per the 32-bit boot protocol
+ xorl %ebp, %ebp # Per the 32-bit boot protocol
+ xorl %edi, %edi # Per the 32-bit boot protocol
movl %cr0, %edx
orb $1, %dl # Protected mode (PE) bit