Month: January 2024

I’m just writing this down in case anyone has a similar issue.

As per Building Red Hat Enterprise Linux 9 for the x86-64-v2 microarchitecture level | Red Hat Developer, back in 2020, AMD, Intel, Red Hat, and SUSE collaborated to define three x86-64 microarchitecture levels on top of the x86-64 baseline. The three microarchitectures group together CPU features roughly based on hardware release dates:

• x86-64-v2 brings support (among other things) for vector instructions up to Streaming SIMD Extensions 4.2 (SSE4.2)  and Supplemental Streaming SIMD Extensions 3 (SSSE3), the POPCNT instruction (useful for data analysis and bit-fiddling in some data structures), and CMPXCHG16B (a two-word compare-and-swap instruction useful for concurrent algorithms).
• x86-64-v3 adds vector instructions up to AVX2, MOVBE (for big-endian data access), and additional bit-manipulation instructions.
• x86-64-v4 includes vector instructions from some of the AVX-512 variants.

This is a great idea and goal except when you have perfectly good old hardware that, while end-of-life is still working and you find it doesn’t support the new compile target.

This nice little awk script from the fine folks over at stackexchange will show you what microarchitecture your cpu supports by looking at the /proc/cpuinfo flags. I’ve included a local copy here and as you can see it’s pretty simple.

#!/usr/bin/awk -f

BEGIN {
    while (!/flags/) if (getline < "/proc/cpuinfo" != 1) exit 1
    if (/lm/&&/cmov/&&/cx8/&&/fpu/&&/fxsr/&&/mmx/&&/syscall/&&/sse2/) level = 1
    if (level == 1 && /cx16/&&/lahf/&&/popcnt/&&/sse4_1/&&/sse4_2/&&/ssse3/) level = 2
    if (level == 2 && /avx/&&/avx2/&&/bmi1/&&/bmi2/&&/f16c/&&/fma/&&/abm/&&/movbe/&&/xsave/) level = 3
    if (level == 3 && /avx512f/&&/avx512bw/&&/avx512cd/&&/avx512dq/&&/avx512vl/) level = 4
    if (level > 0) { print "CPU supports x86-64-v" level; exit level + 1 }
    exit 1
}

Running the awk script on my test system reveals :

$ ./testarch.awk
CPU supports x86-64-v1

The implications of this are annoying for me. I was trying to get awx to work on my little play system, but as the awx container is based on centos9 and compiled requiring at least x86-64-v2 then the awx container just wont start – yes I know there is more to awx than just this container, but it highlights the point nicely in the following command.

$ docker run --rm  ghcr.io/ansible/awx:latest
Fatal glibc error: CPU does not support x86-64-v2

This seems to have started somewhere after awx release 19.5.0