Messages in this thread | | | Date | Fri, 18 May 2012 08:46:01 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v6 04/12] x86/smpboot.c: Don't offline CPU0 if any irq can not be migrated out of it and remove CPU0 check in smp_callin() |
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* H. Peter Anvin <hpa@zytor.com> wrote:
> On 05/14/2012 05:17 AM, Ingo Molnar wrote: > > > > * Tony Luck <tony.luck@intel.com> wrote: > > > >> Biggest code impact of that is the extra code to bring cpu0 > >> back online using NMI instead of INIT. We can't use INIT > >> because if cpu0 gets one, it just resets the whole machine :-( > >> But obviously we'd like to avoid special cases where there is > >> a sane way to do so. > > > > Could we just standardize on NMI bringup during regular bootup? > > > > The first instance has to be SIPI because you can't give the > CPU an NMI without the IDT being setup. We *could* assume > that the processor is parked in real mode with the valid > real-mode IDT set up (in which case the vector at physical > address 8 applies) but that seems to assume a lot from the > BIOS for little gain. In particular I suspect that UEFI-based > BIOSes may very well park the CPU in protected or long mode.
Ok, fair enough.
Thanks,
Ingo
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