On Tuesday 24 May 2022 13:52:47 Segher Boessenkool wrote:

On Tue, May 24, 2022 at 08:12:55PM +0200, Pali Rohár wrote:

quoted

On Tuesday 24 May 2022 12:59:55 Segher Boessenkool wrote:

quoted

On Tue, May 24, 2022 at 11:39:39AM +0200, Pali Rohár wrote:

quoted

gcc e500 compiler does not support -mcpu=powerpc option. When it is
specified then gcc throws compile error:

  gcc: error: unrecognized argument in option ‘-mcpu=powerpc’
  gcc: note: valid arguments to ‘-mcpu=’ are: 8540 8548 native

What?  Are you using some modified version of GCC, perhaps?

Hello! I'm using official gcc version, no special modification.

quoted

No version of GCC that isn't hamstrung can have this output.

gcc for e500 cores has really this output when you pass -mcpu=powerpc.

Upstream gcc dropped support for e500 cores during development of
version 9.

This isn't true.  The SPE instruction extension is no longer supported
(because it wasn't maintained).  Everything else still works.

quoted

But you can still compile and install gcc 8.5.0 (last version
of gcc 8) which has this full e500 support.

Really, you can easily try it. Debian 10 (Buster) has gcc 8.3.0 in its
default installation and also provides packages with cross compilers.
Just run 'sudo apt install gcc-powerpc-linux-gnuspe' on desktop amd64
version of Debian 10, it will install e500 cross compiler.

-mcpu=8540 specify e500v1 and -mcpu=8548 specify e500v2

Aha.  Right, because this config forces -mspe it requires one of these
CPUs.

You can use a powerpc-linux compiler instead, and everything will just
work.  These CPUs are still supported, in all of GCC 9 .. GCC 12 :-)


Segher

Ok. I can use different "generic" powerpc compiler (It should work fine
as you said, as it has also -mcpu=8540 option). But I think that
compilation of kernel should be supported also by that gcc 8.5.0 e500
compiler.

It is really annoying if for compiling kernel is needed different
compiler than for compiling rest of the system (userspace and
bootloader). And for user applications it should be really used e500
SPE-capable compiler due to performance reasons.