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Sender: Richard Henderson <rth7680@gmail.com>
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Date: Fri, 06 Sep 2013 08:20:46 -0700
From: Richard Henderson <rth@twiddle.net>
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Subject: Re: [Qemu-devel] [Bug] qemu-sparc64 broken
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To: Peter Maydell <peter.maydell@linaro.org>
Cc: Stefan Weil <sw@weilnetz.de>, qemu-devel <qemu-devel@nongnu.org>

On 09/06/2013 08:15 AM, Peter Maydell wrote:
> On 6 September 2013 16:12, Richard Henderson <rth@twiddle.net> wrote:
>> On 09/05/2013 09:53 PM, Stefan Weil wrote:
>>> After lots of SIGSEGV, the program indeed finishes successfully,
>>> so my report was wrong - SIGSEGV is not a fatal signal for sparc64.
>>> That's interesting - thank you for this information.
>>
>> It's not just sparc64.
>>
>> That's changed page detection, for determining when to invalidate
>> translation blocks.  For self-modifying code, and more.
> 
> Yeah, but in practice sparc64 does this a huge number of
> times on simple binaries in a way that other linux-user
> guests I looked at just don't. Presumably it's just that
> gcc has for some reason put writable data next to code
> for that target.

It's the (old?) PLT scheme for sparc -- it modifies code on linking.
If you use LD_BIND_NOW=1 it can help speed things up when debugging.


r~