Mailing List Archive: CFLAGS question

CFLAGS question

Oct 24, 2004, 3:42 PM

Post #1 of 3 (164 views)

should you use both mcpu and march? i read that one keeps the
compatibility with other cpus and the other streamlines it for just your
cpu type, well....im my case, im not using biniaries for any other
machine on here, why would you need both? i have right now
CFLAGS="-mcpu=pentium4 -march=pentium4 -O3 -pipe -fomit-frame-pointer"
am i slowing myself down by keeping compatibility with other cpus? do i
really need it? im looking for suggestions here.

thanks

nick

--
gentoo-user@gentoo.org mailing list

Re: CFLAGS question [ In reply to ]

glennpj at charter

Oct 24, 2004, 8:10 PM

Post #2 of 3 (160 views)

Permalink

On Sun, 2004-10-24 at 22:42 +0000, Nick Smith wrote:

> should you use both mcpu and march? i read that one keeps the
> compatibility with other cpus and the other streamlines it for just your
> cpu type, well....im my case, im not using biniaries for any other
> machine on here, why would you need both? i have right now
> CFLAGS="-mcpu=pentium4 -march=pentium4 -O3 -pipe -fomit-frame-pointer"
> am i slowing myself down by keeping compatibility with other cpus? do i
> really need it? im looking for suggestions here.

You do not need both but having -mcpu will not slow you down as the
-march option implies the -mcpu (-mtune) option for the i386 platform.
Thus you are not actually keeping compatibility for other CPUs. Note
that this is not necessarily the case for other architectures.

--
Glenn Johnson <glennpj@charter.net>

--
gentoo-user@gentoo.org mailing list

Re: CFLAGS question [ In reply to ]

res0r9lm at tampadsl

Oct 24, 2004, 8:53 PM

Post #3 of 3 (171 views)

Permalink

Glenn Johnson wrote:

>On Sun, 2004-10-24 at 22:42 +0000, Nick Smith wrote:
>
>
>
>>should you use both mcpu and march? i read that one keeps the
>>compatibility with other cpus and the other streamlines it for just your
>>cpu type, well....im my case, im not using biniaries for any other
>>machine on here, why would you need both? i have right now
>>CFLAGS="-mcpu=pentium4 -march=pentium4 -O3 -pipe -fomit-frame-pointer"
>>am i slowing myself down by keeping compatibility with other cpus? do i
>>really need it? im looking for suggestions here.
>>
>>
>
>You do not need both but having -mcpu will not slow you down as the
>-march option implies the -mcpu (-mtune) option for the i386 platform.
>Thus you are not actually keeping compatibility for other CPUs. Note
>that this is not necessarily the case for other architectures.
>
>
>
The reason to use -mcpu or -mtune is some ebuilds strip -march

--
gentoo-user@gentoo.org mailing list