On Tuesday 21 Feb 2017 21:26:20 Walter Dnes wrote:
> On Tue, Feb 21, 2017 at 10:19:16PM +0000, Mick wrote
> 
> > Perhaps I do not understand ... why should the chrooted system need
> > to use different flags?
> 
> See
> https://gcc.gnu.org/onlinedocs/gcc-4.9.4/gcc/i386-and-x86-64-Options.html#i
> 386-and-x86-64-Options
> 
>   The desktop is "-march=ivybridge" and the netbook is "-march=bonnell".
> Neither of them can run the other's "-march=native" code.  "ivybridge"
> does not have MOVBE, while "bonnell" does not have SSE4.1, SSE4.2,
> POPCNT, AVX, AES, PCLMUL, FSGSBASE, RDRND and F16C.  gcc will gladly
> build for whatever Intel cpu you tell it to.  I can build "bonnell" code
> on the "ivybridge".  But I can't run it on the "ivybridge" machine.
> 
>   As a compromise, I suppose I could declare the chroot "-march=core2".
> "core2" is "bonnell" minus MOVBE, so both the netbook and the desktop
> could run that code, with the netbook getting some, but not all, of the
> possible optimization.
> 
>   I have a "hot backup" to my desktop, which has a "silvermont" cpu.
> That's a newer Atom cpu, and it can run "bonnell" code, no problem.  But
> the "ivybridge" machine is not that old, and I prefer to keep my
> machines until they start dying.

I probably misunderstood your intent.  I thought you have 3 PCs and want to 
build binary packages for the oldest/slowest PC only, within a chroot on the 
fastest PC.  The 2 faster PCs build their own packages and do not need a 
chroot build environment.
-- 
Regards,
Mick

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