Messages in this thread | | | Date | Tue, 22 Jul 2008 11:10:56 -0700 | From | Suresh Siddha <> | Subject | Re: [PATCH] x86: add apic probe for genapic 64bit v2 |
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On Tue, Jul 22, 2008 at 11:05:17AM -0700, Yinghai Lu wrote: > On Tue, Jul 22, 2008 at 10:57 AM, Suresh Siddha > <suresh.b.siddha@intel.com> wrote: > > Yinghai, though not directly realted to this probe cleanup, what is this > > 'max_physical_apicid' doing. > > > > I don't understand the need for this commit. > > > >> commit e0da33646826b66ef933d47ea2fb7a693fd849bf > >> Author: Yinghai Lu <yhlu.kernel@gmail.com> > >> Date: Sun Jun 8 18:29:22 2008 -0700 > >> > >> x86: introduce max_physical_apicid for bigsmp switching > >> > >> a multi-socket test-system with 3 or 4 ioapics, when 4 dualcore cpus or > >> 2 quadcore cpus installed, needs to switch to bigsmp or physflat. > >> > >> CPU apic id is [4,11] instead of [0,7], and we need to check max apic > >> id instead of cpu numbers. > > > > for logical flat, it really shouldn't matter how large the physical apic id > > is. In logical flat, OS programs the LDR and the limitation is the > > number of cpu's which is '8'. > > before i clean up 32bit, 64bit already used max_physical_apicid to > check if need to switch to physflat.
No. It was introduced by your commit e0da33646826b66ef933d47ea2fb7a693fd849bf
we were using num_possible_cpus > 8 check before.
> for 32bit, if not switch to bigsmp, cpu with physical apic id >=8 can > not be started by BSP.
why?
thanks, suresh
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