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

[Maxim Levitsky]

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 @#$%^& OS
>
> So we're doing something wrong.  Please try the appended patch.
>
> > I then proceeded to test recently posted low memory corruption patch, and
> > it did show that that @#$%^& BIOS does corrupt low memory 
> > I then reserved all low memory, but system began to hand after first suspend,
> > in exactly same way, but as expected I soon discovered, that that forces real
> > mode page to be above 1M, ok, then I reserved almost all low memory except
> > 100K window in the middle, so low allocations will work, but be placed in
> > region bios less likely to corrupt, and still that didn't help, still same hang.   
> >  

More information, I compiled kernels back to 2.6.19, and they all have exactly the same issue.


Any ideas?

Best regards,
	Maxim Levitsky
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