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linuxboot: fix gdt address calculation

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The gdt address calculation in linuxboot.bin is broken in two ways: first
it loads %cs into %eax, but that instruction leaves the high bits of %eax
undefined and we did not clear them.  Secondly, we completely ignore the
incorrect %eax, and use the undefined %ebx instead.

With these issues fixed, linuxboot works again.

Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Avi Kivity 2009-12-24 15:38:50 +02:00 • committed by Anthony Liguori
parent 810f49b56a
commit d0652aa8ac
1 changed files with 3 additions and 2 deletions
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5
pc-bios/optionrom/linuxboot.S
View file

@ -86,9 +86,10 @@ copy_kernel:
/* Now create the GDT descriptor */ /* Now create the GDT descriptor */
movw $((3 * 8) - 1), -16(%bp) movw $((3 * 8) - 1), -16(%bp)
mov %cs, %eax mov %cs, %eax
movzwl %ax, %eax
shl $4, %eax shl $4, %eax
addl $gdt, %ebx addl $gdt, %eax
movl %ebx, -14(%bp) movl %eax, -14(%bp)
/* And load the GDT */ /* And load the GDT */
data32 lgdt -16(%bp) data32 lgdt -16(%bp)