| Message ID | 1261661930-11888-1-git-send-email-avi@redhat.com |
|---|---|
| State | New |
| Headers | show |
On 12/24/2009 02:38 PM, Avi Kivity wrote: > 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. Wow, I wonder how it worked for me... Paolo
On 12/24/2009 07:38 AM, Avi Kivity wrote: > 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> > Applied. Thanks. Regards, Anthony Liguori > --- > pc-bios/optionrom/linuxboot.S | 5 +++-- > 1 files changed, 3 insertions(+), 2 deletions(-) > > diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S > index c4c9109..8aebe51 100644 > --- a/pc-bios/optionrom/linuxboot.S > +++ b/pc-bios/optionrom/linuxboot.S > @@ -86,9 +86,10 @@ copy_kernel: > /* Now create the GDT descriptor */ > movw $((3 * 8) - 1), -16(%bp) > mov %cs, %eax > + movzwl %ax, %eax > shl $4, %eax > - addl $gdt, %ebx > - movl %ebx, -14(%bp) > + addl $gdt, %eax > + movl %eax, -14(%bp) > > /* And load the GDT */ > data32 lgdt -16(%bp) >
diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S index c4c9109..8aebe51 100644 --- a/pc-bios/optionrom/linuxboot.S +++ b/pc-bios/optionrom/linuxboot.S @@ -86,9 +86,10 @@ copy_kernel: /* Now create the GDT descriptor */ movw $((3 * 8) - 1), -16(%bp) mov %cs, %eax + movzwl %ax, %eax shl $4, %eax - addl $gdt, %ebx - movl %ebx, -14(%bp) + addl $gdt, %eax + movl %eax, -14(%bp) /* And load the GDT */ data32 lgdt -16(%bp)
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> --- pc-bios/optionrom/linuxboot.S | 5 +++-- 1 files changed, 3 insertions(+), 2 deletions(-)