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References: <1458222382-6498-1-git-send-email-sergey.fedorov@linaro.org>
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From: Sergey Fedorov <serge.fdrv@gmail.com>
Message-ID: <56F97AFE.2020401@gmail.com>
Date: Mon, 28 Mar 2016 21:42:06 +0300
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Subject: Re: [Qemu-devel] [PATCH 4/5] tcg: reorder removal from lists in
	tb_phys_invalidate
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To: sergey.fedorov@linaro.org, qemu-devel@nongnu.org
Cc: Paolo Bonzini <pbonzini@redhat.com>, Richard Henderson <rth@twiddle.net>, Peter Crosthwaite <crosthwaite.peter@gmail.com>

On 17/03/16 16:46, sergey.fedorov@linaro.org 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.

Kind regards,
Sergey