One quick question about SMP on ARM

One quick question about SMP on ARM

[rocky]

Hi, all

I am puzzled these day on three issues for SMP ARM in terms of hardware:
1: Is MMU global or per cpu ?
2: Is MicroTLB/MainTLB global or per cpu ?

I read the code, each cpu has to set its own pgd base addr into TBBR0,so I draw the conclusion MMU is per cpu;
ASID is shared between each cpu, while when ASID rollover from 0xff back to 0x0, each cpu has to call local_flush_tlb_all to invalidate I/D tlb; Does that mean MicroTLB/MainTLB is also per cpu; then why all cpu shared ASID from 0x0~0xff ?


I am really confused about this ? any tips
Thanks

rocky









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One quick question about SMP on ARM

[Catalin Marinas]

2011/2/28 rocky <bill_carson@126.com>:
> I am puzzled these day on three issues for SMP ARM in terms of hardware:
> 1: Is MMU global or per cpu ?

Both (if you mean a set of page tables).

> 2: Is MicroTLB/MainTLB global or per cpu ?

Per CPU.

> I read the code, each cpu has to set its own pgd base addr into TBBR0,so I
> draw the conclusion MMU is per cpu;

Yes, but they could also point to the same TTB, for example when a
multithreaded application has threads running on different CPUs.

> ASID is shared between each cpu, while when ASID rollover from 0xff back to
> 0x0, each cpu has to call local_flush_tlb_all to invalidate I/D tlb; Does
> that mean MicroTLB/MainTLB is also per cpu; then why all cpu shared ASID
> from 0x0~0xff ?

Because of point 1 above.

-- 
Catalin