3.5.x boot hang after conflicting fb hw usage <driver> vs VESA VGA - removing generic driver

[Dave Airlie]

On Sat, Aug 18, 2012 at 8:28 AM, Randy Dunlap <rdunlap at xenotime.net> wrote:
> On 08/17/2012 03:25 PM, Justin M. Forbes wrote:
>
>> for <driver>, we have verified cases on inteldrmfb, radeondrmfb, and
>> cirrusdrmfb.
>>
>> This is the last message displayed before the system hangs.  This seems
>> to be hitting a large number of users in Fedora, though certainly not
>> everyone.  This started happening with the 3.5 updates, and is still an
>> issue.  It appears to be a race condition, because various things have
>> allowed boot to continue for some users, though there is no clear work
>> around. Has anyone else run across this?  Any ideas.  For more
>> background we have the following bugs:
>>
>> inteldrmfb:
>> https://bugzilla.redhat.com/show_bug.cgi?id=843826
>>
>> radeondrmfb:
>> https://bugzilla.redhat.com/show_bug.cgi?id=845745
>>
>> cirrusdrmfb <kvm>:
>> https://bugzilla.redhat.com/show_bug.cgi?id=843860
>>
>> It should be noted that the conflicting fb hw usage message is not new,
>> it has been around for a while, but this is the last message seen before
>> the hang.
>
>
> Hi,  (adding dri-devel mailing list)
>
>
> I started seeing this problem on 3.5-rc6.
>
> AFAICT, the system is not actually hung, it's just that no output
> is showing up on the real (physical) output device (display) -- it's
> going somewhere else (or to the bit bucket).
>

Can we bisect this at all?

I worry the intel one will bisect to where we moved the conflict
resolution earlier, but I'd like to see if applying that patch earlier
causes the issue, since radeon has it.

I haven't reproduced this on any hw I own, I also can't get it under qemu.

Dave.