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From: Peter Maydell <peter.maydell@linaro.org>
Date: Tue, 27 Jun 2017 10:23:38 +0100
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Subject: Re: [Qemu-devel] [PATCH v9 04/26] target: [tcg] Add generic
 translation framework
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To: Richard Henderson <rth@twiddle.net>
Cc: =?UTF-8?B?QWxleCBCZW5uw6ll?= <alex.bennee@linaro.org>, Paolo Bonzini <pbonzini@redhat.com>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, QEMU Developers <qemu-devel@nongnu.org>

On 27 June 2017 at 04:22, Richard Henderson <rth@twiddle.net> wrote:
> On 06/26/2017 11:21 AM, Peter Maydell wrote:
>>
>> x86 definitely gets this totally wrong. I would be unsurprised
>> to find that other variable-length-insn targets do too.
>
>
> For x86, doing this optimally is difficult.  We *could* fix it simply by
> single-stepping when executing within the last 15 bytes of the page.

My feeling is that the "longjump out of translate.c on insn aborts"
approach is pretty confusing and ideally we should get rid of that
entirely in favour of having the translate code handle an error
return from the "load byte/short/word" functions it calls. That might
then make it easier to bail out on page-crossing instructions.

thanks
-- PMM