On Thu, Aug 15, 2013 at 12:41 PM, Kerin Millar <kerfra...@fastmail.co.uk> wrote: >> I use -mtune=native rather than -march=native, that way I can use some >> advanced processor features if they are available, but my system will >> still run if moved to a different host. > > > That's not how -mtune works. If -march is unspecified, it will default to > the lowest common denominator for the platform which prevents the use of any > distinguished processor features. For an amd64 install, that would be > "-march=x86-64". > > Instead, -mtune affects everything that -march doesn't. Though it doesn't > affect the instructions that *can* be used, it may effect which of the > allowed instructions are used and how. For instance, gcc includes processor > pipeline descriptions for different microarchitectures so as to emit > instructions in a way that tries to avoid pipeline hazards:
Thanks very much for the clarification, I appreciate it.
