Messages in this thread | | | Date | Tue, 24 Apr 2012 11:05:18 +0900 (JST) | Subject | Re: [PATCH 2/2] Enter 2nd kernel with BSP | From | HATAYAMA Daisuke <> |
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From: Andi Kleen <andi@firstfloor.org> Subject: Re: [PATCH 2/2] Enter 2nd kernel with BSP Date: Mon, 23 Apr 2012 03:49:15 -0700
>> Split logic into BSP's and AP's: BSP waits for AP halting. >> >> Don't remove variable crashing_cpu for debugging use; useful for >> determining one what CPU crash happens. > > Fenghua has this patchkit to allow offlining the BSP. What happens then? > > It would be good to understand why initializing APs from other APs > should not work. Not aware of such a limitation in x86. > > AFAIK when we online a random cpu after boot there is no effort to do it > from BSP. Why does that work and not from the kexec boot? >
Hello Andi,
I have yet to test what I explain here, so I'm sorry I say these with ``would''.
APs to APs case would be entirely my misunderstanding. The problematic case would be APs to BSP case only.
native_cpu_up avoids to wake up cpu with boot_cpu_physical_apicid, but the boot_cpu_physical_apicid would be just a boot cpu now, which could be non-BSP on the 2nd kernel; equal to crashing cpu on the 1st kernel. It would need to check explicitly whether a given cpu is BSP or not and this would be better fix here. This is suggested by Eric.
Thanks. HATAYAMA, Daisuke
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