From 9f259cc59ba45b8db401d60be9700e275676fb15 Mon Sep 17 00:00:00 2001 From: "H. Peter Anvin" Date: Sun, 4 Nov 2007 17:54:31 -0800 Subject: [PATCH] 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 --- arch/x86/boot/pmjump.S | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) 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 @@ * 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 -- GitLab