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From: "Metzger, Markus T" <>
To: Tom de Vries <>
Cc: "" <>
Subject: RE: [PATCH] [gdb/testsuite] Add have_linux_btrace_bug
Date: Mon, 13 Feb 2023 19:17:33 +0000	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Hello Tom,

>The linux kernel commit 670638477aed ("perf/x86/intel/pt: Opportunistically
>use single range output mode"), added in version v5.5.0 had a bug that was
>fixed by commit ce0d998be927 ("perf/x86/intel/pt: Fix sampling using
>single range output") in version 6.1.0.
>The bug manifested for intel microarchitectures Rocket Lake, Raptor Lake and
>Alder Lake.

Actually, it's a h/w bug that got exposed by using single-range output.  It affects
Core processors starting from Ice Lake and it only affects Processor Trace.  Also,
it is only exposed by the py-record-btrace test, which does a lot of single-stepping.

It might be better to just add an XFAIL for that one test.  I'm not sure if maintaining
a processor list makes sense.  The kernel patch disables single-range for > 1 page
for all processors and does not try to maintain a list of affected processors.  We might
want to do the same in GDB and either disable that test for kernels between 5.5 and
6.1, or setup an XFAIL.

The Branch Trace Store issue you found seems to affect all btrace tests on ADL
E-cores.  This is a different issue.  I can reproduce it and I am currently debugging it.


Intel Deutschland GmbH
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  reply	other threads:[~2023-02-13 19:18 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-13 18:10 Tom de Vries
2023-02-13 19:17 ` Metzger, Markus T [this message]
2023-02-14 10:59   ` [PATCH] [gdb/testsuite] Add xfail in gdb.python/py-record-btrace.exp Tom de Vries
2023-02-14 11:34     ` Metzger, Markus T

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