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Re: [Qemu-devel] [PATCH 4/5] tcg: reorder removal from lists in tb_phys_
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From: |
Paolo Bonzini |
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Subject: |
Re: [Qemu-devel] [PATCH 4/5] tcg: reorder removal from lists in tb_phys_invalidate |
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Date: |
Mon, 28 Mar 2016 22:58:08 +0200 |
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User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 |
On 28/03/2016 20:42, Sergey Fedorov wrote:
> On 17/03/16 16:46, address@hidden wrote:
>> First the translation block is invalidated, for which a simple write
>> to tb->pc is enough. This means that cpu-exec will not pick up anymore
>> the block, though it may still execute it through chained jumps. This
>> also replaces the NULLing out of the pointer in the CPUs' local cache.
>
> Although, using 'tb->pc' to mark a TB as invalid is probably not such a
> good idea. There may be some cases when PC could become equal to -1. For
> example, ARMv6-M uses PC >= 0xFFFFFFF0 to perform exception return. So
> we'd better introduce a separate 'tb->valid' or 'tb->invalid' flag.
It is also possible to use tb->flags for that. I suspect that all-ones
tb flags is never valid, but it could also be a #define.
Paolo
[Qemu-devel] [PATCH 3/5] tcg: always keep jump target and tb->jmp_next consistent, sergey . fedorov, 2016/03/17
[Qemu-devel] [PATCH 5/5] tcg: move tb_invalidated_flag to CPUState, sergey . fedorov, 2016/03/17