From 4713c69fa2319fceb5dd939d72a35e8b97c26878 Mon Sep 17 00:00:00 2001 From: Avi Kivity Date: Thu, 24 Dec 2009 15:38:50 +0200 Subject: [PATCH] linuxboot: fix gdt address calculation 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 Signed-off-by: Anthony Liguori (cherry picked from commit d0652aa8ac8d82e077acf8e781557f4c4367dcf5) --- pc-bios/optionrom/linuxboot.S | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S index c4c9109b67..8aebe51ee5 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) -- GitLab