Messages in this thread Patch in this message | | | Date | Thu, 3 Nov 2016 13:02:16 -0700 (PDT) | From | Michal Necasek <> | Subject | Re: 4.8.2 not booting in 32-bit VM without I/O-APIC |
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Hi Thomas,
Sorry for the delay. I can confirm that the problem is fixed in 4.9.0-rc3 and prefill_possible_map no longer crashes (as it did in 4.9.0-rc2). Thank you!
Just a side question, is the previous fix in commit ff8560512b (x86/boot/smp: Don't try to poke disabled/non-existent APIC) actually still required or would the no-op APIC driver take care of it?
Regards, Michal
----- Original Message ----- From: tglx@linutronix.de To: michal.necasek@oracle.com Cc: prarit@redhat.com, ville.syrjala@linux.intel.com, michael.thayer@oracle.com, knut.osmundsen@oracle.com, frank.mehnert@oracle.com, linux-kernel@vger.kernel.org Sent: Friday, October 28, 2016 9:37:31 PM GMT +01:00 Amsterdam / Berlin / Bern / Rome / Stockholm / Vienna Subject: Re: 4.8.2 not booting in 32-bit VM without I/O-APIC
On Fri, 28 Oct 2016, Thomas Gleixner wrote:
> On Fri, 28 Oct 2016, Michal Necasek wrote: > > > > Sorry if I wasn't clear. No, it doesn't work for us. The ff8560512b8d > > commit fixes the APIC poking on machines where there is no local APIC > > available (and thus fixes the committer's machine), but it doesn't work > > in our case, where there is a local APIC but no I/O APIC, no ACPI MADT, > > and no MP tables. > > > In other words, for us boot_cpu_has(X86_FEATURE_APIC) is true but the > > APIC has not been set up yet because init_apic_mappings() hasn't been > > run.
Right. That mapping setup is an utter trainwreck as we do it from multiple places, but there is no reason why we can't move it before the call to prefill_possible_map().
Thanks,
tglx
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index bbfbca5fea0c..b59fdba3cbdf 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -1221,11 +1221,13 @@ void __init setup_arch(char **cmdline_p) */ get_smp_config(); + /* Make sure apic is mapped before prefill_possible_map() */ + init_apic_mappings(); + prefill_possible_map(); init_cpu_to_node(); - init_apic_mappings(); io_apic_init_mappings(); kvm_guest_init();
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