[Amiga] Linux and a 68040
Ronan Mullally
I'm posting this for someone who's had a go at getting the 680x0 version
(v0.04 or v0.05 I think) working on their 68040... I myself know nothing,
about Amigas....
Forwarded message:
Question: what is supposed to happen if you type:
bootstrap -k vmlinux -r ramdisk.img ? My machine crashes :( If
it's supposed to work, then it might be because I've got AGA, perhaps
because I've got an A4000, and perhaps because the MMU in my EC030
isn't quite up to the job. I hope it's one of the first two! The MMU
works very well with Enforcer, and *seems* to be OK, but then again...
--
Ronan Mullally
-----------------------------------------------------------
320 Sutton Park, Sutton, | Fidonet: 2:263/151 (TOPPSI)
Dublin 13, Ireland | Internet: ro...@bermuda.ucd.ie
--
Ronan Mullally /------------------------------
---------------------------------------| Fax: +353-1-6767984
Systems & Software Engineering, | Voice: +353-1-6767551 x258
Fitzwilliam Court, Dublin 2, Ireland. | Internet: mull...@sse.ie
Philip Mucci
have no MMU, period. This in turn means that you will never be able to
run a full fledged Unix on your machine without getting a new processor.
(Minix runs without an MMU because it doesn't do VM.)
As for Linux, it will be a while before it makes it to an 040.
This is because the 040 implements a subset of the MMu instructions
of an 030 thus making the port difficult. Once the 030 is *functional*,
then someone (with an 040) will pick up on getting the appropriate
stuff ported. I'll post any news I receive here. If you are interested
in helping out with the 040 stuff (which means you are intimate with 040
MMU programming) send me email and I will put you in touch with
the appropriate persion.
_Phil
Hamish Macdonald
>>>>> In message <CBurq...@sse.ie>,
>>>>> mull...@sse.ie (Ronan Mullally) wrote:
Ronan> Question: what is supposed to happen if you type:
Ronan> bootstrap -k vmlinux -r ramdisk.img ?
If you have a 68040 it's going to crash, because Linux/68k doesn't yet
support the 68040.
If you have a 68EC030, it's going to crash, because you don't have a
functioning MMU.
If you have AGA with a full 68030, I don't know what would happen,
because I don't know of anybody who has tried this yet. I don't know
if the current display code can display anything on AGA graphics.
Ronan> [...] and perhaps because the MMU in my EC030 isn't quite up to
Ronan> the job. I hope it's one of the first two! The MMU works very
Ronan> well with Enforcer, and *seems* to be OK, but then again...
If you have a 68EC030, then the MMU doesn't work at all. You just
*think* it does because enforcer catches *some* illegal accesses.
Enforcer can catch illegal accesses to non-existent memory, because
the computer hardware generates a bus fault, which enforcer can
decode. Enforcer uses the MMU to protect certain chunks of valid
memory in the Amiga (e.g. ROM, exception vectors). If your MMU
doesn't work, then enforcer won't catch any accesses (e.g. a write to
ROM) to these areas.
If you run the "lawbreaker" program which comes with enforcer, you'll
probably find that it only catches one enforcer hit (an access to a
non-existent address). If your MMU was functioning properly, it would
catch a number of hits, including a few accesses to low memory.