GCC4 and volatile effects on xorg-x11

[Thomas Winischhofer]

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Thomas Winischhofer wrote:
> Lonni J Friedman wrote:
> 
>>>On 7/17/05, Jim Cornette <jim-cornette at insight.rr.com> wrote:
>>>
>>>
>>>>Hi,
>>>>I am new to the list and could not find discussions from the last two
>>>>months on GCC4 optimizations which cause misbehaving xorg-x11 servers on
>>>>various cards. The problems seem to effect Intel, MGA, cyberblade and
>>>>varous other drivers. Replacing the libvgahw.a file with a version
>>>>compiled for a previous distribution of Fedora Core 3 will get X up and
>>>>running again. Recent tests show that using lesser optimization will
>>>>allow X to work on a larger amount of hardware, but not all hardware is
>>>>made to work again with gcc4 and reduced optimization.
>>>>
>>>>A thread on the gcc list that refers to this problem is listed below.
>>>>
>>>>http://gcc.gnu.org/ml/gcc/2005-07/msg00699.html
>>>>
>>>>I use the compiled binaries from distributions mostly. I do not know a
>>>>lot about coding. I think people are working on resolving the changes
>>>>which caused the many failures with X on certain hardware.
>>>>
>>>>Ny troubles are with an Intel 815 displaying a blue border with wrapped
>>>>text when changing to a virtual terminal. On an Intel 865G, the
>>>>terminals are blank. Changing the libvgahw.a fixes both issues. Using
>>>>lessor compilation errors fixes the Intel 815 but not the Intel 865G.
>>>>
>>>>X seems to work great in the GUI. The problem is with the virtual terminals.
>>>>
>>>
>>>
>>>FWIW, I'm also seeing identical behavior here with those two intel
>>>chipsets.  These two bugs seem to be relevant:
>>>https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=161242
>>>https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=160420
>>>
>>>
> 
> 
> This affects all drivers that are using mmio for accessing i/o ports.

.... through the vgaHW module, to be exact.

> The visual effects might be different on different hardware, though.
> 
> I suggest you file a bug at freedesk.org's bugzilla (unless someone else
>  already did).
> 


- --
Thomas Winischhofer
Vienna/Austria
thomas AT winischhofer DOT net          http://www.winischhofer.net/

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