Kernel v3.13 hang during boot now that dpm is enabled for radeon driver - Radeon HD4870
Submitted by Ome..@..il.com
Assigned to Default DRI bug account
Created attachment 95961
Kernel log for session with manual radeon module loading with modesetting enabled
Flagged as major as this prevents kernel boot if the user doesnt know how to disable the functionality with the kernel boot parameters.
Originally reported in https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=741619 , Debian kernel v3.13 enables dpm by default - partway through the boot process (when cryptsetup is opening encrypted disks), the kernel hangs (confirmed with no response to ping).
The kernel boots fine with radeon.dpm=0.
Following instructions (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=741485#10) I booted with radeon.modeset=0, made sure X wasn't running and radeon was unloaded, then modprobe'd radeon modeset=1 - after a small delay everything hung.
I have attached kern.log (REISUB FTW this time it seems?), there is an X log but that simply gave up after finding no modesetting support, before the point where I reloaded radeon.
kern.log is verbose as I always boot with full debugging information, but in this case its useless as nothing appears to be logged associated with the radeon load (and I'm assuming the magic sync worked).
In terms of fighting the issue, I have C and C++ experience but no real kernel debugging EXP and certainly nothing todo with the graphical stack.
uname -a: Linux omega1 3.13-1-amd64 #1 SMP Debian 3.13.5-1 (2014-03-04) x86_64 GNU/Linux
X server: 1.15.0
Attachment 95961, "Kernel log for session with manual radeon module loading with modesetting enabled":