[Buildroot] [PATCH 02/11] arch: MIPS: Add config option BR2_GCC_TARGET_TUNE
Yann E. MORIN
yann.morin.1998 at free.fr
Thu Apr 3 22:12:15 UTC 2014
Paul, All,
On 2014-04-03 23:50 +0200, Paul Cercueil spake thusly:
> This patch would pass the same value to --with-arch and --with-tune, unless
> you define a different value for BR2_GCC_TARGET_TUNE in your defconfig.
I see what you expect, but since BR2_GCC_TARGET_TUNE is a prompt-less
option, setting it in a defconfig will be overriden when you use that
defconfig.
For example:
$ cat defconfig
BR2_MIPS=y
BR2_GCC_TARGET_ARCH="FOO-YEM"
$ make BR2_DEFCONFIG=$(pwd)/defconfig defconfig
[...]
$ grep FOO .config
[empty, nada, zilch]
So, even if you set it in your defconfig, BR2_GCC_TARGET_ARCH is lost.
Ditto for BR2_GCC_TARGET_TUNE.
> We
> use that for the Ingenic jz4740 processor, which is a mips32 processor but
> running better the code tuned for mips32r2.
Oh, I see. But that's not gonna happen with this code, I'm afraid.
Can you double-check that it is indeed working for you? Because if it
does, we have a really big bug in Kconfig (Oh, no, not one more...)
Regards,
Yann E. MORIN.
> On 03/04/2014 23:19, Yann E. MORIN wrote:
> >Paul, All,
> >
> >On 2014-04-03 23:01 +0200, Paul Cercueil spake thusly:
> >>This option is actually already used in GCC's package.
> >>
> >>This allows to optimize the toolchain for a specific MIPS processor
> >>while supporting more than one family of processors.
> >Is that really needed? man gcc says:
> >
> > When this option is not used, GCC optimizes for the processor
> > specified by -march.
> >
> >Since this patch would pass the same value to --with-arch and
> >--with-tune, and since this is the default of gcc, is it really
> >needed?
> >
> >Neither ACKing nor NAKing this patch. Can you explain a bit more why we
> >would want that, given the above explanations?
> >
> >Regards,
> >Yann E. MORIN.
> >
> >>Signed-Off-By: Paul Cercueil <paul at crapouillou.net>
> >>---
> >> arch/Config.in.mips | 10 ++++++++++
> >> 1 file changed, 10 insertions(+)
> >>
> >>diff --git a/arch/Config.in.mips b/arch/Config.in.mips
> >>index 20951e0..e4160a2 100644
> >>--- a/arch/Config.in.mips
> >>+++ b/arch/Config.in.mips
> >>@@ -83,6 +83,16 @@ config BR2_GCC_TARGET_ARCH
> >> default "mips64" if BR2_mips_64
> >> default "mips64r2" if BR2_mips_64r2
> >>+config BR2_GCC_TARGET_TUNE
> >>+ default "mips1" if BR2_mips_1
> >>+ default "mips2" if BR2_mips_2
> >>+ default "mips3" if BR2_mips_3
> >>+ default "mips4" if BR2_mips_4
> >>+ default "mips32" if BR2_mips_32
> >>+ default "mips32r2" if BR2_mips_32r2
> >>+ default "mips64" if BR2_mips_64
> >>+ default "mips64r2" if BR2_mips_64r2
> >>+
> >> config BR2_MIPS_OABI32
> >> bool
> >> default y if BR2_mips || BR2_mipsel
> >>--
> >>1.9.0
> >>
> >>_______________________________________________
> >>buildroot mailing list
> >>buildroot at busybox.net
> >>http://lists.busybox.net/mailman/listinfo/buildroot
>
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