Re: CortexM3 GCC 4.3.2

["Yann E. MORIN" <yann dot morin dot 1998 at anciens dot enib dot fr>]

Vivek,
All,

On Tuesday 18 November 2008 14:23:59 Vivek Kumar Gupta wrote:
> I understand that now mcpu is deprecated so I have not used in setting.

-mcpu is not deprecated for ARM. To my knowledge, -mcpu is deprecated only
for i386 & x86_64.

> When I use Architure level as "armv7m" and Tune for CPU as "cortex-m3"
> [ALL  ]    For  real value is 
> [ALL  ]    For cortex-m3 real value is cortexm3
> [ALL  ]    Unknown arch used in --with-arch=armv7m

According the gcc manual, the real name is armv7-m.

> [ALL  ]    For cortex-m3 real value is cortexm3
> [ALL  ]    For cortex-m3 real value is cortexm3
> [ALL  ]    Unknown arch used in --with-arch=armv7-m

After grepping for "real value is" through the gcc sources, the above error
message comes from gcc-4.3.2/gcc/config.gcc.

According to that file, the only supported arch to be used with --with-arch=
are:  armv[23456]  armv2a       armv3m       armv4t
      armv5t       armv5te      armv6j       armv6k
      armv6z       armv6zk      iwmmxt       ep9312

Looks like it's missing some recent values... :-( OK, svn blame tells us that
the piece of code responsible for this check was last touched at revision
88937, which was committed in Oct 2004. More than four years ago... :-(

So armv7-m can not be a default arch. In your case, to generate code for the
Cortex-M3, I'd simply set -mpcu and -mtune. Or if you feel brave, you could
try to come up with a new patch to gcc...

Regards,
Yann E. MORIN.

BTW, it took me approximately 20 minutes to come up with these results with a
little bit of grep, a litle bit of www, and a little bit of svn blame... ;-)
Which is not so much for someone that is directly concerned with the problem,
but is quite some time for someone that is not, and is doing it on its spare
time instead of doing its own stuff... Not saying that questions shouldn't be
asked, but even a little research would have answered the question much faster
than posting and waiting for the answer...
YEM.

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