BSP for MIPS32 4KC

[mikeci at acm.org]

Hi!

See the inline answers:

>
> OK, it seems we have some problems communicating.  I know you have a
> working BSP, but we can't just commit changes without understanding the
> implications.  I think we really must identify what MIPS32 means, so
> please answer the following questions;
>
> - What revision is your processor, R3000 or R4000?
My processor is MIPS 4Kc which is based on MIPS32 architecture.

> - What is the Register width?  (this is 32, from above)

32 bit registers.

> - Why will __mips == 3 not work?

Problem is that you can mix modules compiled with mips=1 and mips2 with
modules compiled with mips=3 and mips=4. Anyway, this makes life difficult
because than you need to pass cpu= to gcc. By using mips=32 you can
support all MIPS32 cpus. All the gcc libraries are compiled with mips=1,
and you can't mix them. Then, again I don't know how can you distinguish
between libraries compiled with mips=3 and mips=1. Is there a support in
the gcc for this?

> - Do you need CP1 support or not?  Your patch simply deletes the
>   mathco support, which isn't appropriate for commiting into RTEMS
> because other MIPS bsp's use it.  To resolve this, I think we'll need
> to do bsp #includes in the cpukit code, or test for
>   -msoft-float, which shouldn't be all that horrible, but we have to
> know what we're doing.

My processor doesn't have CP1, and I had problems with the code dealing
with floating point. I don't know why this code was included in my code
even when defining -msoft-float and setting appropriate constants in cpu.h
(MIPS_HAS_FPU).  This is the reason why I deleted that part. For all
other, this must be left in.


> Thanks,
>
> Gregm