Re: ARMLinux on ARM710 / Kinetic
On Sun 04 Feb, Richard Atterer wrote:
> Does ARMLinux run on pre-StrongARM processors now (in my case, an
> ARM710 inside my RiscPC)? IIRC, there was some discussion about this a
> few months ago and somebody said "there are a few problems now, but it
> should work soon". So, does it?
Yes. No problems that I am aware of (specific to ARM6/7 that is :-). There
were some reported a while back (which is what you are referring to above),
but it seems this was spurious.
> On a related issue, are there any problems with those Kinetic upgrade
> cards from Castle?
Yes. DMA doesn't work if you have one in, so the kernel will boot as far as
the first HD access and then things go wrong. This can be worked around by
putting on the 'behave as a normal StronARM' link at which point it works
fine, but the extra memory and speed are not available.
We've done some work on supporting this but didn't finish. It looks as if
support is quite strightforward for 2.4 kernels (harder on 2.2 kernels due to
changes in the number of dicontiguous memory blocks supported).
We have all the specs from Castle and can reveal them to selected people in
order to get the device supported (Castle are indeed a bit nervous about
everyone knowing about their hardware, but have at least made the info
available on acceptable terms).
This is approx what needs doing (notes from tak-shing chan who looked at
1. CONFIG_DISCONTIGMEM support for RPC (arch/arm/config.in,
refer to their SA1100 counterparts);
2. Separating DMA memory from normal memory (not sure how
hard this is, it could involve lots of rewrites in
arch/arm/mm/init.c and related places);
3. DMA access to normal memory should be disallowed (this
might be easy when  is done);
[Russell says there is a thing already there to limit DMA access to a
small region, W]
4. Special initialisation code for the SDRAM Configuration
register and the VRAM Flag Config Register
should be added to arch/arm/kernel/setup.c.
There is also a question of what do you do about the fact that you have a
load of fast memory and load of slow memory - is there any way to
preferentially allocate the fast stuff?
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