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

[Dave Airlie]

On Tue, Aug 21, 2012 at 8:45 AM, Randy Dunlap <rdunlap at xenotime.net> wrote:
> On 08/19/2012 10:22 PM, Dave Airlie wrote:
>
>> On Mon, Aug 20, 2012 at 3:13 PM, Randy Dunlap <rdunlap at xenotime.net> wrote:
>>> On 08/17/12 15:55, Dave Airlie wrote:
>>>
>>>> On Sat, Aug 18, 2012 at 8:54 AM, Dave Airlie <airlied at gmail.com> wrote:
>>>>> 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 guess I'll have to try again.  My first attempt did not
>>> prove anything, I think because the conflict does not happen
>>> 100% of the time (i.e., it feels like a timing problem).
>>>
>>>>> 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.
>>>
>>> Do you know of a specific commit that I could revert and test?
>>
>> 9f846a16d213523fbe6daea17e20df6b8ac5a1e5
>>
>> might work, but it just changes the timing mostly.
>>
>> also testing 3.4 with that on top would be good.
>
>
> That commit doesn't apply cleanly to 3.4, but reverting
> it on 3.5-rc6 (where I first saw the problem) allows me to boot
> 3.5-rc6 multiple times without a problem.
>
> Maybe Justin can get more stable testing done also..

Randy do you have a vga= on your kernel command line?

Dave.