I'm running a small-form-factor PC with an 855GM chipset, and X hangs during startup leaving me with a blank screen on my VGA output. This happens in 2.4.0 from git, in the current git head (commit 27e9506fda86e90fd67de1715fa32d23aaa8a683), and in 2.3.2-2+lenny1 from Debian sid. It does _not_ happen in 2.3.2-2+lenny2, and the only difference between those two is that 2.3.2-2+lenny1 includes a cherry-picked patch from 2.4.0 that force-enables pipe A on 855GM, and 2.3.2-2+lenny2 doesn't.
This is the backtrace I get from gdb when attaching to the hung X process (using the git head version of the intel driver):
0xb7b0a5da in i830_crt_detect (output=0x9db1818) at i830_crt.c:285
285 while ((dsl = INREG(pipe_dsl_reg)) <= vsample)
#0 0xb7b0a5da in i830_crt_detect (output=0x9db1818) at i830_crt.c:285
#1 0x080f64b0 in xf86ProbeOutputModes (scrn=0x9daf0e0, maxX=2048, maxY=2048)
#2 0x080f6e24 in xf86InitialConfiguration (scrn=0x9daf0e0, canGrow=0)
#3 0xb7b15d10 in I830PreInit (pScrn=0x9daf0e0, flags=<value optimized out>)
#4 0x080ab42f in InitOutput (pScreenInfo=0x8210bc0, argc=3, argv=0xbf9a6f84)
#5 0x08074591 in main (argc=3, argv=0xbf9a6f84, envp=0xbf9a6f94)
I'm running the core server version 1.4.2-2 from Debian sid. I'll attach my config and log.
Created attachment 18072 [details]
Created attachment 18073 [details]
There's also a separate bug in Debian's bug tracker describing this problem on a laptop: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=493096
reassign to Jesse.
Can you see what vsample value it's waiting for at that point? It looks like the current logic is tight in that it can result in a border size of 1, but it should eventually work...
In the meantime I'll try hooking a monitor to my 855 laptop and seeing what happens.
I can't reproduce on my 855 laptop... can you enable the modedebug option and attach a new log?
ping bug reporter...
Sadly, I don't have time to respond to my xorg bugs with anything like reasonable speed anymore. See my comments in bug #11368 for more.
Hm, this doesn't seem to happen in 2.4.2-1 from Debian experimental. I'm fine with assuming it got fixed since 2.4.0.