Re: [MiNT] Sparemint Coldfire

[Paul Wratt <paul.wratt@gmail.com>]

(could not post this for 3 days now, bit late, but still relevant)

Great work Mark, and unfortunately I dont have anything to contribute
yet, soon hopefully (but hard without any hardware)

2010/1/3 Vincent Rivière <vincent.riviere@freesbee.fr>:
> Mark Duckworth wrote:
>>
>> In the coming weeks I will be rebuilding all of sparemint for coldfire.
>
> Excellent. But it will be a lot of work.
> The main problem is that the only compiler for ColdFire is GCC 4.x, most
> SpareMiNT sources are really outdated. As I have already underlined, old
> software often need some minor patches to be compatible with GCC 4.x.
> We would probably have more chances to have a ColdFire distribution with
> Alan's Gentoo which use up to date packages.
> And also, there is the problem that the RPMs can't be cross-compiled...
>
Again, SRC2PKG should be able to do this no problem, unless you
specifically mean:
"v4e RPM's created with v4e RPM"

>> I will be using m5474 arch and -mcpu=5474 cflag.  So a package for
>> coldfire will look like 'aalib-1.2-1.m5474mint.rpm.
>
> Currently, we have 3 ColdFire processors around:
> - The ACP computer use the MCF5474
> - The Freescale evaluation boards use the MCF5484 and the MCF5485
>
> All of these use a V4e core and are fully compatible. The only
> differences are the clock speed and the additional hardware controllers
> built into the processors.
>
> The same compiler options can be used for all V4e processors. In the GCC
> sources, the 5475 has been chosen arbitrarily as the default model for
> the V4e family. For example, the m68k-linux use the 5475 CPU for the V4e
> multilib. So I did the same in the m68k-atari-mint patches, and in the
> MiNTLib, etc.
>
> I really believe there are no differences by compiling with -mcpu=5474
> or -mcpu=5475 or any other V4e CPU. I have explicitly verified that any
> V4e CPU option links the correct V4e multilibs from the m5475 directory.
> However it could be theoretically possible to write sources that behave
> differently on specific processors by using specific defines, but I
> really believe no one does that because there is no good reason.
>
would this not make more sense then:
aalib-1.2-1.m5474-v4e-mint.rpm
aalib-1.2-1.m5475-v4e-mint.rpm
aalib-1.2-1.v4e-mint.rpm

> So when compiling for ColdFire, I recommend using the -mcpu=5475 option
> as it is the GCC default choice, until someone finds a difference
> between the the different CPU models.
>


>> But if that doesn't work I'll be building everything on real coldfire
>> hardware depending on how far away Didier is from having firetos run without
>> cf68klib.
>
> Note that thanks to the CF68KLib, FireTOS can run both 68000 and
> ColdFire executables. Of course the ColdFire ones are faster. It could
> be theoretically possible to run the standard 68000 EasyMiNT on FireTOS
> on the evaluation boards, then to use GCC to build native ColdFire RPMs,
> and progressively replace the 68000 binaries by ColdFire ones for
> improved speed.
>
this looks like a good way to go, presuming that v4e does not need any
patches applied to source, or is that the point of the previous
comments, that it still needs minimal patching (compared to other 68k
variant output).

BTW: why is there still a need to patch is the source is C/C++, wasn't
that the point of another discussion re: ASM. I do however understand
the need to patch for GCC 4.x "strictness" due to the age of
sources...

> Good luck.
>
> --
> Vincent Rivière
>