[Bug 789607] New: Currently emulating unsupported memory accesses in /lib/tls glibc libraries.
https://bugzilla.novell.com/show_bug.cgi?id=789607 https://bugzilla.novell.com/show_bug.cgi?id=789607#c0 Summary: Currently emulating unsupported memory accesses in /lib/tls glibc libraries. Classification: openSUSE Product: openSUSE 12.2 Version: Final Platform: i686 OS/Version: Other Status: NEW Severity: Normal Priority: P5 - None Component: Basesystem AssignedTo: bnc-team-screening@forge.provo.novell.com ReportedBy: per@computer.org QAContact: qa-bugs@suse.de Found By: --- Blocker: --- User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:11.0) Gecko/20100101 Firefox/11.0 Hardware: temp65: HP Proliant DL380G3, dual 2.8GHz HT Xeon, 4Gb memory, RAID5 Software: openSUSE 12.2, xen-4.2.0 built from source. This is from a xenhost on openSUSE 12.2: *************************************************************** ** WARNING: Currently emulating unsupported memory accesses ** ** in /lib/tls glibc libraries. The emulation is ** ** slow. To ensure full performance you should ** ** install a 'xen-friendly' (nosegneg) version of ** ** the library, or disable tls support by executing ** ** the following as root: ** ** mv /lib/tls /lib/tls.disabled ** ** Offending process: mount (pid=45) ** *************************************************************** /lib/tls does not exist. Andreas, the following do exist: # ls -1 /lib/i686/nosegneg/ libc-2.15.so libc.so.6 libm-2.15.so libm.so.6 libpthread-2.15.so libpthread.so.0 librt-2.15.so librt.so.1 libthread_db-1.0.so libthread_db.so.1 I don't know if they're being used or not. It is entirely possible that I just need to build xen with the right configure option. Reproducible: Always -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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Per Jessen
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Andreas Jaeger
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Per Jessen
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--- Comment #3 from Andreas Jaeger
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--- Comment #4 from Andreas Schwab
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--- Comment #5 from Per Jessen
Who is producing that warning?
I am assuming it is some xen startup script/process. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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--- Comment #6 from Per Jessen
(In reply to comment #4)
Who is producing that warning?
I am assuming it is some xen startup script/process.
I should have added that it is in the dmesg output. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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--- Comment #7 from Andreas Jaeger
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--- Comment #8 from Andreas Schwab
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--- Comment #9 from Per Jessen
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--- Comment #10 from Andreas Schwab
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--- Comment #11 from Per Jessen
What is this xen running then?
Right now, nothing. I've just finished installing it. Maybe I'm misunderstanding your question. (In reply to comment #7)
Can you grep around and figure out where it comes from?
/usr/src/linux-3.4.11-2.16/arch/x86/kernel/fixup.c::do_fixup_4gb_segment -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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--- Comment #12 from Per Jessen
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--- Comment #13 from Per Jessen
/usr/src/linux-3.4.11-2.16/arch/x86/kernel/fixup.c :
Hmm, this comment seems pretty critical:
* **** NOTE **** * Issues with the binary rewriting have caused it to be removed. Instead * we rely on Xen's emulator to boot the kernel, and then print a banner * message recommending that the user disables /lib/tls.
Okay, I don't know now - when googling the warning message, the postings go back at least 6 years, so it's nothing new. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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--- Comment #14 from Per Jessen
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Andreas Jaeger
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Andreas Jaeger
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Jan Beulich
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--- Comment #17 from Andreas Jaeger
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Andreas Jaeger
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--- Comment #19 from Per Jessen
Ok, since this is only a problem of 32-bit Hypervisor, I'm removing this from our spec file for glibc now:
%ifarch i386 i486 i586 # Add this to avoid performance penalty on Xen for 32-bit x86 # Note on i686 we build a special library BuildFlags="$BuildFlags -mno-tls-direct-seg-refs" %endif
Why not leave it in, is it causing a problem? Anyway, I wasn't expecting a fix, I know that we don't "support" 32bit xen. I had just hoped for some help with resolving this issue. What I don't understand is - if we've been building glibc with this support up until now, why do I see this problem in 12.2? Btw, https://bugzilla.redhat.com/show_bug.cgi?id=708406 discussed the use of "hwcap 1 nosegneg" only 6 months ago. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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--- Comment #20 from Andreas Jaeger
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--- Comment #21 from Per Jessen
I made some changes for 12.2 and rearranged the code - and added a nosegneg i686 library. Might be that something was wrong there. These are the change entries: Tue Jan 3 19:42:17 UTC 2012 - aj@suse.de
- Compile unwind-dw2-fde-glibc.c with -fno-strict-aliasing (patch glibc-strict-aliasing.diff) - Build on i686 a separate library for usage under Xen.
Okay, I got the (wrong) impression this had been in place for a while.
------------------------------------------------------------------- Tue Jan 3 15:36:12 UTC 2012 - aj@suse.de
- Only use -mno-tls-direct-seg-refs on 32-bit x86, it's not needed on x86-64.
Btw. the spec file change is just one change of a couple similar that might cause performenace penalties for every user using glibc - and we build the nosegneg library that meant building and installing the i686 glibc twice.
I guess the idea is to build those nonegseg libraries separately and then enable their use with ldconfig. It looks like that is what Redhat is doing. If I understand your change correctly, we will now not be building those libraries, so I will just have to do that myself? Btw, adding "hwcap 1 nosegneg" didn't seem to make a difference, maybe I'll take a closer look at what RH actually did to fix this. -- Configure bugmail: https://bugzilla.novell.com/userprefs.cgi?tab=email ------- You are receiving this mail because: ------- You are on the CC list for the bug.
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--- Comment #22 from Andreas Jaeger
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