crosscompiler and porting notes

[Wenqi Chen]

codesourcery revison of GCC-4.3 does seem to support armv7-a compiler
flag/NEON instruction set.

2009/5/19 Mark Tinguely <tinguely at casselton.net>:
>
> sorry for the blank reply. It should have said
>
> Looking at the current sources for the GNU assembler, it appears to me that
> the "gas" sources do not have some new and important ARMv7 commands such as
> "dmb", "dsb", and "isb" (barriers). There ARMv6 equivalent command, but
> are not recommended.
>                        ---
> I looked at the Cortex document, the first thing that changed in ARMv7
> is the information registers (for example information on the caches).
> You will need to replace the CPU information and intialization code.
>
> It would be nice to get an ARMv7 ARM. Someone with authority, like the
> FreeBSD Foundation may be needed.
>                        ---
> You will need to write a new cpufunc_asm_XXX.S file of routines. The
> existing routines assume the pmap will flush the caches on context change.
>                        ---
> I would suggest you start by using the existing memory model of flushing
> caches on context changes until we learn more on the Cortex cache - are they
> *really* not effected by the cache coloring problem.
>
> If you can get the console working, and are willing to put some test
> code into somewhere like pmap_bootstrap(), to test if the cache coloring
> is really fixed, I would write it up.
>                        ---
> I have some rough code for the new ARMv6/ARMv7 TLS registers, the tlb ASID
> and load and store exclusive. You have plenty to do to get the board up
> to single user, without having to worry about this other stuff.
>
> --Mark.
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-- 
WC