Bug#613670: linux-image-2.6.32-bpo.5-686: EDID checksum failure kills X while switched away using KVM switch

[Jonathan Nieder <jrnieder@gmail.com>]

Hi Conrad,

Conrad Hughes wrote:

> I'm using a keyboard-video-mouse (KVM) switch to switch between a number
> of computers; before squeeze, this worked brilliantly.  Since upgrading
> to squeeze, a few minutes after I switch to another computer, my squeeze
> install kills X completely.  All I'm seeing is the following in
> /var/log/syslog:
[...]
> [drm:edid_is_valid] *ERROR* EDID checksum is invalid, remainder is 130
> [drm:edid_is_valid] *ERROR* Raw EDID:
> <3>00 ff ff ff ff ff ff 00 ff ff ff ff ff ff ff ff
> <3>ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
[...]
> A similar problem has turned up in Microsoft Windows 7, where continuous
> checking of EDID results in the OS switching to default monitor
> resolution after the user switches away (or even turns off their monitor
> in some cases).  Microsoft apparently blame this on obsolete KVM
> hardware and AFAICS have not offered a facility to disable the
> continuous checking; I hope there might be a means of disabling the
> check in Debian though

Thanks for reporting it, and sorry for the slow response.  I wonder if
the change v2.6.35-rc1~18^2~2 (drm/edid: Allow non-fatal checksum
errors in CEA blocks, 2010-05-25[1]) would help here.

Could you test v2.6.35 or later (e.g., by grabbing a kernel from sid
or experimental with initramfs-tools + linux-base from
squeeze-backports)?

Jonathan

[1] https://bugs.freedesktop.org/28229