Patchwork Make -kernel for linux work with bochsbios

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Submitter Alexander Graf
Date Nov. 17, 2009, 4:49 p.m.
Message ID <1258476556-32472-1-git-send-email-agraf@suse.de>
Download mbox | patch
Permalink /patch/38660/
State New
Headers show

Comments

Alexander Graf - Nov. 17, 2009, 4:49 p.m.
While trying to run -kernel with -bios pc-bios/pcbios.bin, I realized
that I was actually writing data to %es, but only set up %ds to a 32-bit
segment we want to write to.

So at the end of the day the data hasn't actually been copied. Oops.

So here's a fix to set ES instead of DS, which makes -kernel work with
BOCHS bios again (and actually makes the code do the correct thing)!

Signed-off-by: Alexander Graf <agraf@suse.de>
---
 pc-bios/optionrom/linuxboot.S |   10 +++++-----
 1 files changed, 5 insertions(+), 5 deletions(-)
Alexander Graf - Nov. 30, 2009, 1:10 p.m.
Alexander Graf wrote:
> While trying to run -kernel with -bios pc-bios/pcbios.bin, I realized
> that I was actually writing data to %es, but only set up %ds to a 32-bit
> segment we want to write to.
>
> So at the end of the day the data hasn't actually been copied. Oops.
>
> So here's a fix to set ES instead of DS, which makes -kernel work with
> BOCHS bios again (and actually makes the code do the correct thing)!
>   

ping
Paolo Bonzini - Nov. 30, 2009, 1:50 p.m.
On 11/30/2009 02:10 PM, Alexander Graf wrote:
> Alexander Graf wrote:
>> While trying to run -kernel with -bios pc-bios/pcbios.bin, I realized
>> that I was actually writing data to %es, but only set up %ds to a 32-bit
>> segment we want to write to.
>>
>> So at the end of the day the data hasn't actually been copied. Oops.
>>
>> So here's a fix to set ES instead of DS, which makes -kernel work with
>> BOCHS bios again (and actually makes the code do the correct thing)!
>>
>
> ping

ACK

Paolo

Patch

diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S
index 08c1ca6..ecd9cf2 100644
--- a/pc-bios/optionrom/linuxboot.S
+++ b/pc-bios/optionrom/linuxboot.S
@@ -102,11 +102,11 @@  copy_kernel:
 	mov		$1, %eax
 	mov		%eax, %cr0
 
-	/* So we can set DS to a 32-bit segment */
+	/* So we can set ES to a 32-bit segment */
 	mov		$0x10, %eax
-	mov		%eax, %ds
+	mov		%eax, %es
 
-	/* We're now running in 16-bit CS, but 32-bit DS! */
+	/* We're now running in 16-bit CS, but 32-bit ES! */
 
 	/* Load kernel and initrd */
 	read_fw_blob(FW_CFG_KERNEL)
@@ -118,9 +118,9 @@  copy_kernel:
 	mov		$0, %eax
 	mov		%eax, %cr0
 
-	/* DS = CS */
+	/* ES = CS */
 	mov		%cs, %ax
-	mov		%ax, %ds
+	mov		%ax, %es
 
 	jmp		boot_kernel