Re: Panic when starting X with Intel KMS

Al 17/07/2013 21:05, En/na Gustau Pérez i Querol ha escrit:
> Hi,
>
>    I'm having panics or hard freezes when starting X with an Intel 
> video card. The machine is able to start old X+twm without problems 
> but when I try gnome3 (in normal or fallback mode, doesn't matter) the 
> machine panics or hard freezes.
>
>    This doesn't happen when running X with vesa. With vesa the gnome 
> is able to start in fallback (no composition) mode. Also, an old i386 
> with an nvidia card is able to run that gnome3 with composition so I'd 
> say it has to do with the intel card.
>
>    These are the specs of the machine:
>
>      FreeBSD 10.0-CURRENT #4 r+3dc57aa: Wed Jul 17 15:13:07 CEST 2013
>      root_at_portgus:/usr/obj/usr/src/sys/CUSTOM amd64
>      FreeBSD clang version 3.3 (tags/RELEASE_33/final 183502) 20130610
>      RAM: 8GB
>      Video Card: Intel chipid=0x00468086
>
>    The debugging knobs in the kernel config are there. I can also 
> confirm that I can break to the debugger with CTRL+ALT+ESC before 
> starting X. The world was build without debug symbols.
>
>    Because the machine runs with an Intel card, I had to use my $work 
> dockstation to obtain a serial port and do the debug via serial port 
> with another machine.
>
>   When starting X, either the machine freezes hard (and so no 
> CTRL+ALT+ESC) or the machine panics. It has never executed X without 
> panics or freezes.
>
>    I was able to obtain a core dump, the results are at:
>
>         https://dl.dropboxusercontent.com/u/2094962/core.txt.4
>
>    I was unable to dive any further because the dump only shows the 
> kernel side of things. The bt only seems to show the kernel side and 
> the user side of things seems to be corrupt.
>
>    Any other info I can obtain from the machine in the moment of the 
> panic, let me know. I can easy do the debug via serial port.
>
>    Gus
>

    Reading the backtrace I see this:

          panic: pmap_release: pmap resident count -398580 != 0

    which comes from amd64/amd64/pmap.c:1936. I suspect that 
pmap->pm_stats.resident_count being negative is a bug.

    Can this be caused by a userspace process? If that's possible, any 
idea why I get a corrupted stack an thus I'm not able to find the root 
of the problem.

    G.


-- 
    Salut i força,

    Gustau

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O O O Gustau Pérez i Querol
O O O Unitat de Gestió dels departaments
O O O Matemàtica Aplicada IV i Enginyeria Telemàtica

       Universitat Politècnica de Catalunya
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