On 07/11/16 at 21:52 +0100, Lucas Nussbaum wrote: > Hi, > > On 06/11/16 at 17:41 -0200, Henrique de Moraes Holschuh wrote: > > On Sun, 06 Nov 2016, Ben Hutchings wrote: > > > It's worth noting that TSX is broken in 'Haswell' processors and is > > > supposed to be disabled via a microcode update. I don't know whether > > > glibc avoids using it on these processors if the microcode update is > > > not applied. (Linux doesn't appear to hide the feature flags.) > > > > It does avoid it. For glibc libpthreads, Debian has blacklisted Intel > > TSX use [in libpthreads] on all of Haswell and much of Broadwell. > > > > But anything else *will* attempt to use it, people query cpuid directly > > for these things. You need a hypervisor that filters cpuid(). > > How can one know what glibc does on a given CPU? (preferably without > access to the hardware) > > I could try to run an archive rebuild on hardware where glibc leverages > TSX to see what happens.
I did an archive rebuild on Amazon EC2 using m4.16xlarge instances, that use a CPU with TSX enabled. I've filed bugs for the packages that failed during that rebuild, but don't fail on m4.large instances: https://bugs.debian.org/cgi-bin/pkgreport.cgi?tag=qa-ftbfs-20161111;users=debian...@lists.debian.org It's not impossible that some of them are caused by problems with building in parallel, unrelated to TSX. L.