Request for testers: glibc update to work around Intel TSX errata microcode_ctl problems.

[Hans de Goede]

Hi All,

On 09/26/2014 08:34 PM, Carlos O'Donell wrote:
> Developers.
> 
> Testers wanted immediately for:
> 
> https://admin.fedoraproject.org/updates/glibc-2.18-16.fc20
> 
> and
> 
> https://admin.fedoraproject.org/updates/glibc-2.20-4.fc21
> 
> For Fedora 21 and Fedora 20 we will be disabling Intel TSX
> support in POSIX threads effective immediately. This disabling
> of TSX support in POSIX threads is in order to prevent users
> from crashing their systems when they upgrade microcode_ctl.
> 
> The upgrade to the new microcode_ctl applies the microcode
> update for the Intel errata HSW136 and makes all TSX instructions
> invalid opcodes. This means that any process on your system
> already using POSIX threads, and already using TSX, will fault
> with invalid opcode errors when it tries to execute TSX
> instructions.
> 
> The best solution is for the microcode update to be done before
> userspace starts as part of a single-threaded init process or
> something similar.
> 
> Until we support updating microcode in early bootup we won't
> enable TSX in POSIX threads. The glibc maintainers have decided
> not add code to detect which devices the errata applies to, nor 
> will code be added to re-read the cpuid values at every TSX usage.
> We are going with the simples approach which is to disable TSX
> for POSIX threads.

I've just tested the F-21 update for this, and I'm afraid that the
problem is still present there. I've also regenerated my initrd to make
sure that that included the new glibc too, but that did not help.

Regards,

Hans



> 
> Cheers,
> Carlos.
>