KMS and Radeon RS880 (HD 4200)

Godfrey Benitez xlistmail at
Wed Jul 14 16:02:17 PDT 2010

On Wed, 7/14/10, alexdeucher wrote:
> On Wed, Jul 14, 2010 at 8:29 AM, xlistmail wrote:
> > I have an AMD 785G-based motherboard with built-in Radeon
> > graphics identified by lspci as "ATI Technologies Inc RS880
> > [Radeon HD 4200]". I can easily get month-long uptimes
> > when Kernel Mode Setting is disabled. However, when KMS
> > is enabled, the screen locks within two days of running
> > continuously, sometime even less. By lock, I mean the monitor
> > turns black. The keyboard still appears responsive, I can
> > toggle Num Lock and Caps Lock on and off,  and I can issue
> > Ctrl-Alt-Delete to reboot the computer.
> >
> > The bug appears to be randomly triggered. It has happened
> > while I am running widely different programs like Firefox
> > and Abiword. (Surprisingly, the bug has yet to happen
> > when I'm playing a presumably graphics-intensive 3D game
> > like Glest). Interestingly, however, the bug happens more
> > frequently (it happens faster) when I choose to reboot the
> > computer (hot restart) rather than shut it down and then
> > turn it back on (cold start).
> >
> > The kernel log (kern.log) shows a string of error messages
> > that begins (trimmed to avoid spamming the list):
> That's a GPU lockup.  Unfortunately, unless you have a reliable test
> case, it's very hard to track down the cause.
> > Jul 14 16:45:19 localhost kernel: [121762.072083] [drm:radeon_fence_wait]
> > *ERROR* fence(ffff880076f71a40:0x0130ECFB) 504ms timeout going to reset GPU
> > Jul 14 16:45:19 localhost kernel: [121762.072096] radeon 0000:01:05.0: GPU
> > softreset
> > Jul 14 16:45:19 localhost kernel: [121762.072101] radeon 0000:01:05.0:
> > R_008010_GRBM_STATUS=0xA27334AC


Thanks for the reply. I was just hoping there was some other magic
option I could pass to modprobe besides "radeon modeset=(0|1)"?
modinfo gives several other options for the radeon module, omitting
the obviously nonrelevant ones like benchmark, tv and testing:

no_wb:Disable AGP writeback for scratch registers (int)
dynclks:Disable/Enable dynamic clocks (int)
r4xx_atom:Enable ATOMBIOS modesetting for R4xx (int)
vramlimit:Restrict VRAM for testing (int)
agpmode:AGP Mode (-1 == PCI) (int)
gartsize:Size of PCIE/IGP gart to setup in megabytes (32,64, etc)
connector_table:Force connector table (int)
new_pll:Select new PLL code for AVIVO chips (int)

Also, while I'm running without KMS at the moment, I remember seeing a BIOS
warning when I restarted my system after the X freeze. If I recall correctly
it mentioned something about a "sync flood". My IGP is using a combination
of UMA plus sideport memory (with no option to run on Sideport alone.)

Is there a difference in the way the kernel handles modesetting so that
user mode doesn't crash?


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