Re: [ECOS] Choosing a HAL for M68331

[Jesper Skov <jskov at redhat dot com>]

>>>>> "Per" == Per Østergaard <per@k64.dk> writes:

Per> Hi I'm about to make a port for the Motorola 68331,=20

Per> Which of the mbx860- or mbx821-HAL is the best choice for
Per> starting a = port ?

There is no such things as mbx860 and mbx821 HALs. There is an MBX
platform HAL which primarily provides details about the memory layout
of the MBX board and early startup code.

The mpc8xx variant HAL and QUICC HAL provide support for the various
8xx CPUs - but the difference is only in caching sizes, IIRC.

The QUICC HAL implements drivers for the SMC serial controller. This
should be usable with no or few changes on the m68k as far as I
understand what Moto did with the MPC8xx series (basically took the
68k QUICC controller logic and slapped it on the side of a PPC die).



But since you're talking m68k, you need to create a new
architecture. There will not be much that can be shared between the
PPC and the m68k HALs.  M68k porting has been mentioned on this list a
few times in the past - you may want to try and coordinate efforts
with other interested parties.

As for the QUICC HAL - it's just a simple serial HAL driver for the
SMC. You can simply clone that into the new m68k tree.

So you'll get:

 hal/m68k/arch/...          [clone an existing architecture, change to
                             support generic m68k family]
 hal/m68k/683xx/...         [I don't know how much (if at all) the
                             68331 differs from (say) a 68030, but if
                             there are big differences
                             (CPU/CACHE/MMU), they should probably go
                             in a variant HAL]
 hal/m68k/<platform>/...    [basically memory layout and startup code
                             for your platform. hal_diag/plf_stub
                             serial functions should call QUICC HAL
                             functions]
 hal/m68k/quicc/...         [basically copy of hal/powerpc/quicc. Will
                             need to fix addresses etc.]


Cheers,
Jesper