The first (re)boot after updating F-21 on my laptop (after not updating it for a while) failed to boot, after some debugging I've come to the conclusion, that either a recent glibc change, or a recent intel cpu microcode update has caused me to hit the same issue as documented here. https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=762195 I assume this is caused by a microcode update which now disables hle on haswell while some processes are already using it (e.g. systemd*). As a workaround I've created an /etc/modprobe.conf.d/blacklist.conf file with the following line in there: blacklist microcode Which stops the microcode update from applying. Likely the microcode update is disabling hle for a good reason though, and a proper fix would be for glibc to recognize cpu-s with the errata in question and have it not trying to use hle there at all.
Please test the latest glibc and provide karma so we can push this into f21 quickly. *** This bug has been marked as a duplicate of bug 1146967 ***