• Linus Torvalds's avatar
    x86: Fix booting with "no387 nofxsr" · 8ccb3dcd
    Linus Torvalds authored
    
    
    Jesper Juhl reported that testing the software math-emulation by forcing
    "no387" doesn't work on modern CPU's.
    
    The reason was two-fold:
     - you also need to pass in "nofxsr" to make sure that we not only don't
       touch the old i387 legacy hardware, it also needs to disable the
       modern XMM/FXSR sequences
     - "nofxsr" didn't actually clear the capability bits immediately,
       leaving the early boot sequence still using FXSR until we got to
       the identify_cpu() stage.
    
    This fixes the "nofxsr" flag to take effect immediately on the boot CPU.
    
    Debugging by Randy Dunlap
    Acked-by: default avatarRandy Dunlap <rdunlap@xenotime.net>
    Cc: Jesper Juhl <jesper.juhl@gmail.com>
    Cc: Andi Kleen <ak@suse.de>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    8ccb3dcd