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authorH. Peter Anvin <hpa@zytor.com>2007-11-04 20:54:31 -0500
committerH. Peter Anvin <hpa@zytor.com>2007-11-04 22:48:04 -0500
commit9f259cc59ba45b8db401d60be9700e275676fb15 (patch)
treedc57ec27c11c98fbb2ed4448d13030c4fc0b6cca /arch
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>
Diffstat (limited to 'arch')
-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 26baeab3a4d4..fa6bed1fac14 100644
--- a/arch/x86/boot/pmjump.S
+++ b/arch/x86/boot/pmjump.S
@@ -28,11 +28,13 @@
28 * void protected_mode_jump(u32 entrypoint, u32 bootparams); 28 * void protected_mode_jump(u32 entrypoint, u32 bootparams);
29 */ 29 */
30protected_mode_jump: 30protected_mode_jump:
31 xorl %ebx, %ebx # Flag to indicate this is a boot
32 movl %edx, %esi # Pointer to boot_params table 31 movl %edx, %esi # Pointer to boot_params table
33 movl %eax, 2f # Patch ljmpl instruction 32 movl %eax, 2f # Patch ljmpl instruction
34 33
35 movw $__BOOT_DS, %cx 34 movw $__BOOT_DS, %cx
35 xorl %ebx, %ebx # Per the 32-bit boot protocol
36 xorl %ebp, %ebp # Per the 32-bit boot protocol
37 xorl %edi, %edi # Per the 32-bit boot protocol
36 38
37 movl %cr0, %edx 39 movl %cr0, %edx
38 orb $1, %dl # Protected mode (PE) bit 40 orb $1, %dl # Protected mode (PE) bit