illegal instruction - create compile variants ?

[Kevin Kofler]

David Timms wrote:
> Should I be suggesting to upstream to attempt to detect CPU before
> running non-available instructions, eg as part of app startup ?

Yes, this is the ONLY solution that's acceptable for binary packaging in 
distributions. Otherwise, we can only build the most generic version. (The 
current packages which enable whatever happens to be supported on the build 
system are completely broken and shouldn't have passed review.)

> Can that even be done (reliably) ?

Yes, all the packages which have WORKING support for SSE etc. in Fedora do 
that. See e.g.
https://projects.kde.org/projects/kde/kdelibs/repository/revisions/master/entry/solid/solid/backends/shared/cpufeatures.cpp
https://projects.kde.org/projects/kde/kdelibs/repository/revisions/master/entry/solid/solid/backends/udev/cpuinfo.cpp
https://projects.kde.org/projects/kde/kdelibs/repository/revisions/master/entry/solid/solid/backends/udev/udevprocessor.cpp
for the implementation Solid (in kdelibs) uses.

        Kevin Kofler