Re: i5 and invalid instructions

[David Laight <david%l8s.co.uk@localhost>]

On Tue, Nov 13, 2012 at 09:28:18AM +0000, Jaap Boender wrote:
> Hello all,
> 
> Just got my new work laptop, a Dell with an Intel i5-3320m processor. The 
> first thing I did after installing NetBSD was compile a new kernel and 
> distribution, with the cpuflags package installed.
> 
> cpuflags activates -march=native, which in my case enables everything up to 
> SSE4, AVX and all those other newfangled optimisations new processors have. 
> However, after installing the distribution, every command I try to run core-
> dumps with "Illegal instruction"...

AVX doubles the size of the registers so needs the kernel to detect
this and save the much larger register area on each process switch.

Possibly the first such instruction (in a process) could be allowed
to fault, then be rerun with AVX enabled (for that process) and the
larger resgister save/restore done.

        David

-- 
David Laight: david%l8s.co.uk@localhost