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From: "engelke at in dot tum.de" <sourceware-bugzilla@sourceware.org>
To: glibc-bugs@sourceware.org
Subject: [Bug dynamic-link/29953] New: Invalid x86_non_temporal_threshold without cache info
Date: Mon, 02 Jan 2023 17:33:37 +0000 [thread overview]
Message-ID: <bug-29953-131@http.sourceware.org/bugzilla/> (raw)
https://sourceware.org/bugzilla/show_bug.cgi?id=29953
Bug ID: 29953
Summary: Invalid x86_non_temporal_threshold without cache info
Product: glibc
Version: 2.36
Status: UNCONFIRMED
Severity: minor
Priority: P2
Component: dynamic-link
Assignee: unassigned at sourceware dot org
Reporter: engelke at in dot tum.de
CC: hjl.tools at gmail dot com
Target Milestone: ---
When cpuid reports no information on a shared cache (e.g., in an emulator), the
x86_non_temporal_threshold will be set to zero, causing memcpy/memset to behave
wrong for mid-sized operations. sysdeps/x86/dl-cacheinfo.h indicates that the
minimum value must be 0x4040, but this is not enforced for the default value
(see also commit b446822b6ae).
In the emulator, `/lib64/ld-linux-x86-64.so.2 --list-tunables` reports:
glibc.cpu.x86_non_temporal_threshold: 0x0 (min: 0x0, max:
0xffffffffffffffff)
Setting the tunable explicitly (env
GLIBC_TUNABLES=glibc.cpu.x86_non_temporal_threshold=0x4040) avoids the problem.
As a side note, ld.so won't load any DSO on x86-64 ("CPU ISA level is lower
than required") when the cpuid vendor not listed in sysdeps/x86/cpu-features.c,
as the feature bits in cpuid leaf 1 are not decoded in get_common_indices
(family is NULL).
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next reply other threads:[~2023-01-02 17:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-02 17:33 engelke at in dot tum.de [this message]
2023-01-02 21:21 ` [Bug dynamic-link/29953] " goldstein.w.n at gmail dot com
2023-01-03 0:05 ` goldstein.w.n at gmail dot com
2023-01-03 12:49 ` engelke at in dot tum.de
2023-01-03 16:23 ` hjl.tools at gmail dot com
2023-01-03 17:52 ` goldstein.w.n at gmail dot com
2023-01-03 17:55 ` hjl.tools at gmail dot com
2023-01-03 18:00 ` goldstein.w.n at gmail dot com
2023-01-03 18:04 ` hjl.tools at gmail dot com
2023-01-03 18:13 ` goldstein.w.n at gmail dot com
2023-01-03 18:22 ` hjl.tools at gmail dot com
2023-01-03 18:39 ` engelke at in dot tum.de
2023-01-03 19:24 ` goldstein.w.n at gmail dot com
2023-01-03 21:58 ` cvs-commit at gcc dot gnu.org
2023-01-25 21:05 ` decui at microsoft dot com
2023-03-13 17:59 ` fweimer at redhat dot com
2023-03-13 18:00 ` fweimer at redhat dot com
2023-03-13 18:00 ` fweimer at redhat dot com
2023-03-13 18:17 ` hjl.tools at gmail dot com
2023-03-15 22:18 ` cvs-commit at gcc dot gnu.org
2023-04-20 15:52 ` cvs-commit at gcc dot gnu.org
2023-04-20 15:53 ` cvs-commit at gcc dot gnu.org
2023-05-08 16:44 ` fw at deneb dot enyo.de
2023-05-08 17:09 ` fweimer at redhat dot com
2023-05-08 17:09 ` fweimer at redhat dot com
2023-07-17 7:29 ` fweimer at redhat dot com
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