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SubjectRe: [RFC] VBE DDC bios call stalls boot
On Sun, Apr 23, 2006 at 12:08:27PM -0700, Yum Rayan wrote:

> There is a bios call to check if read EDID is supported. My first
> thought was that before doing read EDID, video.S should first check to
> see if the hardware supports the read EDID feature. Unfortunately that
> bios call too ends up in the woods until I physically
> disconnect/reconnect my CPU video output that feeds into the KVM.

Is this how your patch looked when you tried this ?

Dave

--- linux-2.6.15/arch/i386/boot/video.S~ 2006-01-06 01:26:06.000000000 -0500
+++ linux-2.6.15/arch/i386/boot/video.S 2006-01-06 01:28:40.000000000 -0500
@@ -1951,9 +1951,18 @@ store_edid:
stosl

movw $0x4f15, %ax # do VBE/DDC
- movw $0x01, %bx
+ movw $0x00, %bx # INSTALLATION CHECK / CAPABILITIES
movw $0x00, %cx
- movw $0x00, %dx
+ movw $0x00, %dx
+ movw $0x140, %di
+ int $0x10
+ cmpb $0x01, %ah
+ je no_edid
+
+ movw $0x4f15, %ax # do VBE/DDC
+ movw $0x01, %bx # READ_EDID
+ movw $0x00, %cx
+ movw $0x00, %dx
movw $0x140, %di
int $0x10

--- linux-2.6.15/arch/i386/boot/video.S~ 2006-01-06 02:55:20.000000000 -0500
+++ linux-2.6.15/arch/i386/boot/video.S 2006-01-06 02:55:28.000000000 -0500
@@ -1966,6 +1966,7 @@ store_edid:
movw $0x140, %di
int $0x10

+no_edid:
popw %di # restore all registers
popw %dx
popw %cx
--
http://www.codemonkey.org.uk
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