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authorVivek Goyal <vgoyal@in.ibm.com>2006-01-12 03:35:20 +0100
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-11 19:09:58 -0800
commit983d5dbdb2b38d024935f560a91cddcf704875f3 (patch)
tree834cda0f26f3902aea74d1cd81a9202f78cc5f14
parent0d9cb75f2f41788a59bcd3dac30b264a4bebaf2e (diff)
[PATCH] x86_64: Fix SMP bootup with CONFIG_KDUMP enabled
o This fix was posted for i386 long back. Posting it for x86_64. http://marc.theaimsgroup.com/?l=linux-kernel&m=110380103229830&w=2 o This patch fixes the problem of secondary cpus boot up. This situation is faced when kernel is built for default locations like 16MB and onwards. In this configuration, only primary cpu (BP) comes and secondary cpus don't boot. o Problem occurs because in trampoline code, lgdt is not able to load the GDT as it happens to be situated beyond 16MB. This is due to the fact that cpu is still in real mode and default operand size is 16bit. o This patch uses lgdtl instead of lgdt to force operand size to 32 instead of 16. Signed-off-by: Vivek Goyal <vgoyal@in.ibm.com> Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--arch/x86_64/kernel/trampoline.S11
1 files changed, 9 insertions, 2 deletions
diff --git a/arch/x86_64/kernel/trampoline.S b/arch/x86_64/kernel/trampoline.S
index 6d9c9a8e7d0..23a03eb91fc 100644
--- a/arch/x86_64/kernel/trampoline.S
+++ b/arch/x86_64/kernel/trampoline.S
@@ -42,8 +42,15 @@ r_base = .
movl $0xA5A5A5A5, trampoline_data - r_base
# write marker for master knows we're running
- lidt idt_48 - r_base # load idt with 0, 0
- lgdt gdt_48 - r_base # load gdt with whatever is appropriate
+ /*
+ * GDT tables in non default location kernel can be beyond 16MB and
+ * lgdt will not be able to load the address as in real mode default
+ * operand size is 16bit. Use lgdtl instead to force operand size
+ * to 32 bit.
+ */
+
+ lidtl idt_48 - r_base # load idt with 0, 0
+ lgdtl gdt_48 - r_base # load gdt with whatever is appropriate
xor %ax, %ax
inc %ax # protected mode (PE) bit