Re: [Buildroot] [PATCH v2 1/3] arch: add support for mcf5441x Colfdire

[Thomas Petazzoni via buildroot <buildroot@buildroot.org>]

Hello,

On Wed, 10 Apr 2024 19:12:09 +0200
Jean-Michel Hautbois <jeanmichel.hautbois@yoseli.org> wrote:

> The m68k family ony has one Coldfire variant, namely the 5208. Add the
> support for the MCF5441x CPU family in the configuration file.
> This covers MCF54410, MCF54415, MCF54416, MCF54417 and MCF54418.

Interesting. I always thought that Coldfire meant "no MMU" and 68k
meant "MMU", but I was wrong. The family of 68k and coldfire is quite
messy, difficult to find clear and reliable sources of information.

> +config BR2_GCC_TARGET_ARCH
> +	default "cf"            if BR2_m68k_cf5441x

The problem with this is that "cf" is not a valid value for gcc -march=
option. Look at the documentation at:
https://gcc.gnu.org/onlinedocs/gcc-13.2.0/gcc/M680x0-Options.html

The valid values of -march are:

  Permissible values of arch for M680x0 architectures are: ‘68000’,
  ‘68010’, ‘68020’, ‘68030’, ‘68040’, ‘68060’ and ‘cpu32’. ColdFire
  architectures are selected according to Freescale’s ISA classification
  and the permissible values are: ‘isaa’, ‘isaaplus’, ‘isab’ and
  ‘isac’. 

What happens when you don't specify -march? Do you know which of isaa,
isaaplus, isab and isac the MCF5441x corresponds to?

Best regards,

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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