I believe the most obvious issues we were having was the gsasl tests indirectly triggered by gnutls28 the unrar-free tests triggered by libarchive. Both of which do include valgrind use. In addition to flag being obviously incompatible with valgrind, it also caused issues with gdb for me, and some segmentation faults in gsasl outside any debugging tools (although I did not investigate these in much detail). There are also claims from upstream about the implementation on 32-bit arm being questionable, and no other distros s Mate Kukri
FTR there is no issue in Debian with any of the above in my tests. Also the packages don't seem to use valgrind at any point: not when building, not in the autopkgtests. Full build logs including autopkgtest output here: https://people.debian.org/~ema/armhf-stack-clash-protection/ What exactly did not work in Ubuntu and how? Perhaps there are additional jobs running valgrind in CI that may explain the failures? Thanks, Emanuele