[OE-core] [PATCH 3/3] Add basic PowerPC core tune config
Kumar Gala
galak at kernel.crashing.org
Tue Jul 26 15:22:57 UTC 2011
On Jul 26, 2011, at 8:59 AM, Richard Purdie wrote:
> On Tue, 2011-07-26 at 08:47 -0500, Kumar Gala wrote:
>> On Jul 26, 2011, at 7:44 AM, Richard Purdie wrote:
>>
>>> Signed-off-by: Richard Purdie <richard.purdie at linuxfoundation.org>
>>> ---
>>> meta/conf/machine/include/powerpc/arch-powerpc.inc | 45 +++++++++++++++++++-
>>> meta/conf/machine/include/tune-ppc603e.inc | 12 ++++-
>>> meta/conf/machine/include/tune-ppce300c2.inc | 12 ++++-
>>> meta/conf/machine/include/tune-ppce500.inc | 13 ++++--
>>> meta/conf/machine/include/tune-ppce500mc.inc | 12 ++++-
>>> meta/conf/machine/include/tune-ppce500v2.inc | 12 ++++-
>>> 6 files changed, 88 insertions(+), 18 deletions(-)
>>
>> One thing I'm wondering about as we do this is the ability to pass
>> --with-cpu to gcc & [e]glibc configure to pickup proper optimized cfgs
>> & libs for a given target.
>
> As far as I can tell, gcc 4.x has no --with-cpu option. We pass the
> correct march and mtune options to the compiler at runtime through
> CFLAGS and friends.
Hmm, gcc still supports this:
http://gcc.gnu.org/install/configure.html
--with-cpu=cpu
--with-cpu-32=cpu
--with-cpu-64=cpu
Specify which cpu variant the compiler should generate code for by default. cpu will be used as the default value of the -mcpu= switch. This option is only supported on some targets, including ARM, i386, M68k, PowerPC, and SPARC. The --with-cpu-32 and --with-cpu-64 options specify separate default CPUs for 32-bit and 64-bit modes; these options are only supported for i386, x86-64 and PowerPC.
http://gcc.gnu.org/install/specific.html
powerpc-*-*
You can specify a default version for the -mcpu=cpu_type switch by using the configure option --with-cpu-cpu_type.
> You're already found the way to pass configuration to *libc using values
> in TARGET_FPU to pickup the right configuration.
>
> Is there a use case we're missing?
Yes, for [e]glibc we have optimized libc functions for a given / specific PPC processor. So we need someway to tell configure this.
- k
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