Re: I need some serious help to debug suspend to ram problem

[Maxim Levitsky]

Rafael J. Wysocki wrote:
> On Sunday, 21 of September 2008, Maxim Levitsky wrote:
> > Maxim Levitsky wrote:
> > > Rafael J. Wysocki wrote:
> > > > On Saturday, 20 of September 2008, Maxim Levitsky wrote:
> > > > > Hi,
> > > > >
> > > > > I hit a dead end when trying to understand why my notebook can't 
> > > > > resume from suspend to ram
> > > > > if this is done two times a row.
> > > > >
> > > > > Single suspend/resume cycle works almost perfectly (beep that goes 
> > > > > through the sound card is muted... no morse code for me... :-(
> > > > >
> > > > > )
> > > > >
> > > > > I compiled a minimal kernel (absolutely nothing but disk drivers, all 
> > > > > experimental option like nohz
> > > > > turned off)
> > > > >
> > > > > But I had to turn SMP, since without it system won't resume first 
> > > > > time I suspend it.
> > > > > (How could this affect suspend?)
> > > > It could if the system is 64-bit.  In which case please have a look at
> > > > http://bugzilla.kernel.org/show_bug.cgi?id=11237
> > > >
> > > > > With SMP and minimal kernel (of course  no closed drivers), I get 
> > > > > same behavior,
> > > > > first resume works second hangs.
> > > > >
> > > > > I then added some debug code to real mode wakeup code, I put there in 
> > > > > first
> > > > > place instructions, that will save some magic value to rtc (to alarm
> > > > > registers that I know are preserved during boot cycle), and I 
> > > > > discovered   sad thing that first time bios does pass control to 
> > > > > linux, but second time
> > > > > (when it hangs), it doesn't.
> > > > >
> > > > > I tried to update bios, and I got same results.
> > > > >
> > > > > Of course it does work with that @#$%^& OS
> > > > So we're doing something wrong.  Please try the appended patch.
> > > Thanks a lot, but this didn't help.
> > >
> > > It still has same pattern, first suspend/resume works perfectly, second 
> > > suspend/resume hangs hard.
> > > It always happens like this, first resume always work (unless I turn off 
> > > smp in kernel (I test this again), or reserve all low memory)
> > >
> > > Also note that if I suspend the system to ram, resume, and then suspend 
> > > to disk, then I can suspend to ram and resume, it seems that
> > >
> > > on suspend to ram cycle somehow arms BIOS or something else, so second 
> > > resume in a row doesn't work.
> > >
> > > I run 32 bit kernel here, this is a long story (this bios doesn't turn 
> > > fan on when running 64-bit version, I could update it, and I know that 
> > > fan issue is fixed there, but new bios introduces bigger bug, namely it 
> > > makes fan to run almost always regardless of 32/64 type of os.
> > > And it doesn't fix this suspend/resume issue, I tested this. I could 
> > > start/stop fan manually with a script, but this could fail, and maybe I 
> > > will do so someday.)
> > >
> > > The bugzilla seems to be unrelated here, since bios does pass control 
> > > there, but corrupts memory.
> > > Here I also have seen that bios corrupts memory, but everything resumes 
> > > fine first time, and on second time,
> > > bios doesn't pass control (I put set of instructions in beginning of 
> > > wakeup real mode assembly file, no page tables, GDT/LDT are used there)
> > I did same test for kernel without SMP, yes it hangs on first resume, but bios
> > does pass control to linux, so while this is a minor bug, it is unrelated.
>
> Still, I'd be interested in debugging this one too, if possible.  That may be
> easier too. ;-)

I take a look at that.

> > I also tested noapic, pci=nommconf. No luck.
> >
> > Pattern is always the same, first resume works always, second doesn't.
> > It is sad since first resume is almost perfect (when I have free time I need to look at sound codec datasheet
> > and fix few issues there, anyways here alsa has few issues, all this is trivial, I already fixed all issues with desktop
> > which has a sigmatel codec)
>
> If you have more than 2 GB of RAM, you can try iommu=soft .
>
> I guess that all of the /sys/power/pm_test tests are passed?

Well, I didn't run /sys/power/pm_test. 
But this system has rock solid suspend to disk, I use it always.

iommu? I don't think this mobo has it, it has PM965/GM965/GL960
(according to lspci)


Best regards,
	Maxim  Levitsky
> Thanks,
> Rafael

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