Dear Peter Senna Tschudin, On Tue, 4 Mar 2014 22:26:37 +0100, Peter Senna Tschudin wrote: > I have reported a bug more than two years ago and it is still > affecting me. The bug report gives some information: > > https://bugzilla.redhat.com/show_bug.cgi?id=787299 > > I have tried basic debug instructions from: > https://www.kernel.org/doc/Documentation/power/basic-pm-debugging.txt > > And everything works as expected when: > # echo freeze > /sys/power/state > # echo disk > /sys/power/state > > I have asked for help for fixing it: > https://lkml.org/lkml/2013/11/1/186 > > But I don't have a serial port. How can I debug this issue without a > "real" serial port? Or what else can I try? How can I explore the hint > about the problem only happening with VT-d enabled in BIOS? How can I > explore the hint about the problem not happening if the option > nox2apic is passed to the Kernel? Something I would try in this situation is to boot with mem=<some value smaller than the amount of RAM>, and then have the kernel write some debugging informations manually at a fixed location in RAM that has been reserved by lowering the amount of RAM using mem=. Then, when you reboot, you can dump what has been left in this memory location. Of course this requires that 1/ this memory location is not overwritten by the BIOS/bootloader and 2/ that you can do a warm reset to not loose the contents of the memory. Since I don't do much x86 kernel hacking, I never had to do that on x86, but I've used this trick a few times on ARM platforms. If that works, then it means you can put some debugging details all over the kernel to find where things hand exactly during the resume process. Another embedded trick is to find a LED that you can easily turn on/off. It is very useful to see if you reach a given portion of code or not. Thomas -- Thomas Petazzoni, CTO, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com _______________________________________________ Kernelnewbies mailing list Kernelnewbies@xxxxxxxxxxxxxxxxx http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
