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Re: [PATCH v2 01/12] xen/trace: Don't over-read trace objects


  • To: "andrew.cooper3@xxxxxxxxxx" <andrew.cooper3@xxxxxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>
  • From: Dario Faggioli <dfaggioli@xxxxxxxx>
  • Date: Fri, 24 Sep 2021 14:51:25 +0000
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  • Thread-topic: [PATCH v2 01/12] xen/trace: Don't over-read trace objects

On Mon, 2021-09-20 at 18:25 +0100, Andrew Cooper wrote:

> There is one buggy race record, TRC_RTDS_BUDGET_BURN.  As it must
> remain
> __packed (as cur_budget is misaligned), change bool has_extratime to
> uint32_t
> to compensate.
> 
Mmm... maybe my understanding of data alignment inside structs is a bit
lacking, but what the actual issue here, and what would we need to do
to fix it (where, by fix, I mean us being able to get rid of the
`__packed`)?

If rearranging fields is not enough, we can think about making
priority_level and has_extratime smaller, or even combining them in
just one field and decode the information in xentrace.

Of course, I can send a patch for that myself, even as a followup of
this series when it's in, as soon as we agree about the best way
forward.

Thanks and Regards
-- 
Dario Faggioli, Ph.D
http://about.me/dario.faggioli
Virtualization Software Engineer
SUSE Labs, SUSE https://www.suse.com/
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