Bug 1856398

Summary: glibc: Build with -moutline-atomics on aarch64
Product: Red Hat Enterprise Linux 8 Reporter: Florian Weimer <fweimer>
Component: glibcAssignee: DJ Delorie <dj>
Status: CLOSED ERRATA QA Contact: Sergey Kolosov <skolosov>
Severity: high Docs Contact:
Priority: high    
Version: 8.4CC: ashankar, bgray, codonell, davdunc, dj, frival, fweimer, jlinton, mas, mnewsome, msalter, pfrankli, sipoyare, vmukhame
Target Milestone: rcKeywords: FutureFeature, Patch, Triaged
Target Release: 8.4   
Hardware: aarch64   
OS: Linux   
Whiteboard:
Fixed In Version: glibc-2.28-136.el8 Doc Type: No Doc Update
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2021-05-18 14:36:34 UTC Type: Enhancement
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On: 1821994, 1828472    
Bug Blocks: 1809132, 1877113, 1894575    
Attachments:
Description Flags
moutline-atomics.patch none

Description Florian Weimer 2020-07-13 14:17:26 UTC
We should build glibc with -moutline-atomics on aarch64, to avoid a critical performance regression in the mutex implementation on certain CPUs.

This depends on a GCC change. After that, it is just a three-line glibc.spec change.

Comment 1 Florian Weimer 2020-07-14 17:11:46 UTC
*** Bug 1818100 has been marked as a duplicate of this bug. ***

Comment 2 Florian Weimer 2020-07-14 17:12:02 UTC
*** Bug 1828473 has been marked as a duplicate of this bug. ***

Comment 3 Florian Weimer 2020-07-20 16:18:39 UTC
Created attachment 1701786 [details]
moutline-atomics.patch

Marek provided me with a test build of GCC, and I was able to build glibc with it, using the attached patch. The resulting glibc builds on a system with LSE atomics and selects the expected code path, including in the dynamic loader (so its ELF constructor was executed).

Once we know the GCC version with the patch, we should probably tighten the gcc build dependency as well.

Comment 4 Jeremy Linton (ARM) 2020-07-27 21:27:49 UTC
I found this right before opening a defect requesting much the same thing so +one... :)

Comment 16 errata-xmlrpc 2021-05-18 14:36:34 UTC
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (Moderate: glibc security, bug fix, and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHSA-2021:1585