Comment # 27 on bug 903874 from Andi N Kleen

Ok this is a known problem.

What happens is that the ucode update disables TSX, so disables a bit in the
CPUID. It also makes the TSX instructions fault.

But you have a TSX enabled platform and glibc pthread is using TSX. It only
checks the CPUID at the beginning.

So if you load the ucode update after you started a program using pthreads it
has already checked TSX CPUID and may be using it, and suddenly it gets
disabled, so it gets these faults.

The recommended way to handle it is to load this update only with the early
microcode update from the initrd. This does the update when nothing is running
that could be already using TSX.

Alternatively you can disable TSX in the glibc. The first option is better.