Remove sub-arch/variants selection from the menuconfig

Yann E. MORIN yann.morin.1998 at
Tue Jan 26 22:19:03 UTC 2010

Bernhard, All,

On Tuesday 26 January 2010 19:48:10 Bernhard Reutner-Fischer wrote:
> >On Monday 25 January 2010 21:49:25 Yann E. MORIN wrote:
> >> It is not the responsibility of the C library to select what sub-arch
> >> to generate code for. Rely on the user to:
> >> - either use a compiler that is configured to generate optimised code
> >>   for the target actual target,
> >> - or set UCLIBC_EXTRA_CFLAGS with the correct incantation of -march,
> >>   -mcpu, and the likes.

> With this approach we will just break e.g. sparc who do not (AFAICS)
> have means to distinguish their ISAs?

My gcc (Debian 4.3.4-6~bpo50+1) has -mcpu= and -mtune= flags (and can
be configured with --with-cpu= and --with-tune= flags) to specify the
processor generation, and thus the acceptable instruction set. The
possible values are (from man gcc):
  Sparc arch     Implementation
  v7             cypress
  v8             supersparc, hypersparc
  sparclite      f930, f934, sparclite86x
  sparclet       tsc701
  v9             ultrasparc, ultrasparc3, niagara, niagara2

The -mcpu=[Sparc arch] flag only sets the instruction set, while the
-mcpu=[Implementation] flag sets the instruction set, and optimises for
the scpecific implementation. The -mtune=[whatever] flag only sets the
scheduling optimisations.

Or I don't get what you meant by "ISA". Which has quite a high probability!

> Also -mlittle-endian/-ml/-mel/-EL vs. -mbig-endian/-mb/-meb/-EB/ is just
> stupid.

I do agree, and those should go as well. Furthermore, I think that the
ABI stuff (eg. ARM EABI vs. OABI) should also disapear. There are
preprocessor macros that can be used to determine the current ABI.

Also, the soft- vs. hard-float (at least for ARM) is also configurable,
changes the ABI, and should be testable with preprocessor /tricks/. We
already discussed this on the list with Khem back in April. I'll dig up
the archives.

I'll be able to look into those, but only after FOSDEM. Please poke me
if you don't see anything from me arounf Feb` 15th.

Yann E. MORIN.

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