diff options
authorZachary Amsden <>2007-08-10 22:31:05 +0200
committerLinus Torvalds <>2007-08-11 15:58:13 -0700
commit08da5a2ca479c5e8805dc3f77fd77176c4293399 (patch)
parentab144f5ec64c42218a555ec1dbde6b60cf2982d6 (diff)
x86_64: Early segment setup for VT
VT is very picky about when it can enter execution. Get all segments setup and get LDT and TR into valid state to allow VT execution under VMware and KVM (untested). This makes the boot decompression run under VT, which makes it several orders of magnitude faster on 64-bit Intel hardware. Before, I was seeing times up to a minute or more to decompress a 1.3MB kernel on a very fast box. Signed-off-by: Zachary Amsden <> Signed-off-by: Andi Kleen <> Signed-off-by: Linus Torvalds <>
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/x86_64/boot/compressed/head.S b/arch/x86_64/boot/compressed/head.S
index 1312bfaff30..9fd8030cc54 100644
--- a/arch/x86_64/boot/compressed/head.S
+++ b/arch/x86_64/boot/compressed/head.S
@@ -195,6 +195,11 @@ ENTRY(startup_64)
movl %eax, %ds
movl %eax, %es
movl %eax, %ss
+ movl %eax, %fs
+ movl %eax, %gs
+ lldt %ax
+ movl $0x20, %eax
+ ltr %ax
/* Compute the decompressed kernel start address. It is where
* we were loaded at aligned to a 2M boundary. %rbp contains the
@@ -295,6 +300,8 @@ gdt:
.quad 0x0000000000000000 /* NULL descriptor */
.quad 0x00af9a000000ffff /* __KERNEL_CS */
.quad 0x00cf92000000ffff /* __KERNEL_DS */
+ .quad 0x0080890000000000 /* TS descriptor */
+ .quad 0x0000000000000000 /* TS continued */
/* Stack for uncompression */