Messages in this thread | | | Date | Mon, 17 Dec 2012 14:11:06 +0100 | From | Bernd Schubert <> | Subject | Re: [regression] 3.7 ends in APIC panic |
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On 12/17/2012 11:00 AM, Borislav Petkov wrote: > + Suresh. > > On Mon, Dec 17, 2012 at 10:34:46AM +0100, Bernd Schubert wrote: >> On 12/16/2012 09:39 PM, Borislav Petkov wrote: >>> On Sun, Dec 16, 2012 at 08:46:06PM +0100, Bernd Schubert wrote: >>>> Hmm, I read it the other way around - x2apic depends on interrupt >>>> remapping, but interrupt remapping can be used without x2apic. >>> >>> Ok, you're right. X2APIC should depend on IRQ_REMAP: >>> https://lwn.net/Articles/289881/ >>> >>>> The help text of CONFIG_IRQ_REMAP also says "x2APIC enhancements or to >>>> support platforms with CPU's having > 8 bit APIC ID, say Y." I guess >>>> may CPU has the latter? >>> >>> I think it is what Yinghai said - you obviously need x2apic kernel >>> support if you have IRQ_REMAP on. >>> >>>> Can the kernel panic a bit improved to help user to understand what >>>> needs to be enabled? >>> >>> Well, your kernel enables IRQ_REMAP properly: >>> >>> [ 0.031115] Enabled IRQ remapping in x2apic mode >>> >>> I guess at that stage we could probably check for x2apic support and >>> scream loudly if it is not present... IMHO. >>> >> Hmm, I think that would the wrong place, > > It has to be the right place because this "Enabled IRQ..." printk above > is from the IRQ remapping code which detects an x2apic mode in your > case. > >> as the initial 3.7.0 configuration didn't have IRQ_REMAP enabled. > > Huh, so why do I see the above message in your dmesg output in > http://marc.info/?l=linux-kernel&m=135540103415652 then?
Oh huh, that is the dmesg from 3.4.7, which booted fine. I just sent it hoping it would help to see where the issue comes from. When I run "make oldconfig" for 3.7.0 I accidentally unset CONFIG_IRQ_REMAP, wich also unset CONFIG_X86_X2APIC :(
> > Ok, let's sort things out here. Your .config has > > # CONFIG_IRQ_REMAP is not set > > but in the original dmesg you sent, the printk above comes from > intel_irq_remapping.c which gets enabled by CONFIG_IRQ_REMAP. > > So, can you try enabling only CONFIG_IRQ_REMAP and leave > CONFIG_X86_X2APIC off to confirm the original observation?
No need, as I said above, the printk comes from a different kernel with a different config. With either CONFIG_IRQ_REMAP=false or CONFIG_X86_X2APIC=false the booting ends in a kernel panic.
> > Also, I'd guess your machine can boot with both options off?
No, only partly with "noapic", but that makes ahci to fail to detect disks later on.
> >> And that was the reason why x2apic got disabled during the "make >> oldconfig" process... >> >> Is this message an indication for missing x2apic? >> >> "smpboot: weird, boot (#255) not listed by the BIOS" > > It's an indication that something is fishy with the apic IDs. > > Thanks. >
Cheers, Bernd
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