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Re: Debugging return.exp on ARM
- From: Pedro Alves <palves at redhat dot com>
- To: Simon Marchi <simon dot marchi at ericsson dot com>, gdb at sourceware dot org
- Cc: Yao Qi <qiyaoltc at gmail dot com>
- Date: Thu, 26 May 2016 20:11:36 +0100
- Subject: Re: Debugging return.exp on ARM
- Authentication-results: sourceware.org; auth=none
- References: <574712FC dot 5090409 at ericsson dot com>
On 05/26/2016 04:15 PM, Simon Marchi wrote:
> Given that we give the right input to the kernel, even in the cases that
> fail, I assume that the problem must be something like wrong cache invalidation
> or memory barrier/sequencing.
>
> I ran this test in a loop and got these results:
>
> ODroid XU-4:
> 263 fails
> 737 successes
>
> Firefly RK3288:
> 336 fails
> 163 success
>
> First, is anybody able to reproduce the problem on other boards? Then, does anybody
> have an idea what could cause this?
- I'd suspect something odd with caches / barriers too.
Did you try sprinkling in memory barrier instructions, and
see whether it makes a difference?
- I'd also try "si" + "info regs" instead of "next" after the return,
and see if a register with a bad value pops up always at some
specific instruction.
- I'd try to see if pinning the thread to a core makes a difference.
- Might help to show the kernel version.
Thanks,
Pedro Alves