Looks like it would be intentional according to https://www.mozilla.org /en-US/firefox/53.0/releasenotes/ :
"Ended Firefox Linux support for processors older than Pentium 4 and AMD Opteron" Also, for Windows, they require SSE2 since Firefox 49. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1697800 Title: [regression] firefox dies with SIGILL on machines without SSE2 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/firefox/+bug/1697800/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
