Messages in this thread | | | Subject | Re: [regression bisected] HR-timers bug >=2.6.25 | From | Peter Zijlstra <> | Date | Fri, 16 May 2008 19:31:56 +0200 |
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On Fri, 2008-05-16 at 10:26 -0700, Justin Madru wrote: > Peter Zijlstra wrote: > > The kernel doesn't hang, right? My reading of the description tells me > > the splash just doesn't work. > > > > If it does hang the kernel, an NMI trace collected over serial or > > netconsole (regular console being out of the question since its > > graphical stuff :/) would be most helpful. > > I've seen it blank out in 2 different ways. > > 1) Usplash completely finishes. Then screen goes blank for the usual mode change/screen refreshing, > doing several refreshes of a blank screen. But, the screen then stays black. > I do still hear the gdm sound, and can switch to a console. > Pressing ctrl+alt+f1 makes the screen "refresh" again, but stay blank/black. I can still login but blindly. > > 2) More rarely. Usplash hasn't finished (but near the end). The usplash screen fades out to black. > It's like a screen burn in, or after image; the screen slowly fades out to black. > After this the computer is _seemingly_unresponsive_ - Only alt+sysrq+b seems to work. (I have to hard reset) > After I reboot the backlight is at the lowest level. > > Anyways, I think I can figure out how to set up a netconsole, but > is there something more to setup a NMI trace? I found Documentation/networking/netconsole.txt > But, it doesn't say anything about a NMI trace.
those can be obtained by adding:
nmi_watchdog=[12]
to the kernel boot parameters - it depends a bit on the hardware which of the two choices works best, just start with 1 and if that doesn't work try 2.
This enabled the NMI watchdog and that will print a backtrace when it times out after 30 or so seconds.
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