Messages in this thread | | | From | Jesse Barnes <> | Subject | Re: PCI MSI breaks when booting with nosmp | Date | Mon, 21 Apr 2008 13:40:20 -0700 |
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On Monday, April 21, 2008 1:20 pm Jean Delvare wrote: > Hi Andi, > > Le lundi 21 avril 2008, Andi Kleen a écrit : > > Jesse Barnes <jbarnes@virtuousgeek.org> writes: > > > Ok, I see this too on my desktop machine. It looks like we're not > > > getting interrupts setup correctly in the nosmp case. Still digging > > > through to see why though... > > > > NoSMP disables the io-apic and a lot of modern systems don't work without > > APIC. > > > > If you just want to run with a single cpu for testing etc. always use > > maxcpus=1 (not 0, that will disable the APIC too) > > In my case, booting with noapic works fine, so I don't think that the > problem is related to APIC being disabled.
One difference between noapic and nosmp is that in the nosmp case even the local APIC setup won't occur in native_smp_prepare_cpus(), due to smp_sanity_check() returning -1 in the setup_max_cpus == 0 case.
So we either need smp_sanity_check to do a little more APIC setup if max_cpus == 0 or shuffle things around in native_smp_prepare_cpus(). Since the former is already done for 32 bit builds for the NMI vector, maybe we should just make it unconditional so that MSI works?
Jesse -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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