Gentoo Archives: gentoo-dev

From: Luca Barbato <lu_zero@g.o>
To: gentoo-dev@l.g.o
Subject: Re: [gentoo-dev] Replacing cpu-feature USE flags
Date: Thu, 06 Jul 2006 22:50:53
Message-Id: 44AD92AF.305@gentoo.org
In Reply to: [gentoo-dev] Replacing cpu-feature USE flags by "Diego 'Flameeyes' Pettenò"
1 Diego 'Flameeyes' Pettenò wrote:
2 [summary:provide a way to enable simd features by extracting them from
3 the ones supported by the cflags selected and the compiler]
4
5 Pros:
6 - automagic : you just carefully select your cflags and your apps will
7 have all the simd goodness you may dream/want/expect.
8 - less useflags around
9 - simpler life when building stages (given we gut cpuinfo checks in
10 configures)
11
12 Cons:
13 - assumes gcc
14 - per ebuild cflags feat isn't ready yet
15 - makes less simple to have certain corner case
16
17 Alternatives:
18
19 - as PPC we provide a default cflags & use tuned per certain cpu
20 families using profiles, amd64 could provide a nocona profile that bans
21 3dnow* useflags.
22
23 - have simdflags as use_expand to keep them on a single place and
24 improve the description
25
26 - as before but provide an eclass that uses flameeyes infrastructure to
27 warn about possible mismatch between what the cflags could do and what
28 you expect to obtain eg: -mcpu=nocona use 3dnow would issue a warning
29 and disable it
30
31 - as the one before again but with a var to decide if follow the use or
32 the gcc check.
33
34
35 lu
36
37 --
38
39 Luca Barbato
40
41 Gentoo/linux Gentoo/PPC
42 http://dev.gentoo.org/~lu_zero
43
44 --
45 gentoo-dev@g.o mailing list

Replies

Subject Author
Re: [gentoo-dev] Replacing cpu-feature USE flags Simon Stelling <blubb@g.o>