Subject: Re: HW question & sbic sync patch
To: None <firstname.lastname@example.org.Hawaii.Edu>
From: Niklas Hallqvist <email@example.com>
Date: 08/21/1994 14:21:10
>>>>> "Tim" == Tim Newsham <firstname.lastname@example.org.Hawaii.Edu> writes:
>> >> How about cachectl? Is it an expensive operation to toggle
Michael> Cachectl only deals with pushing the data cache and
Michael> invalidating the caches. Enabling/disabling the cache done
Michael> by manipulating the CACR to control whether caching is
Michael> enabled or not, or by manipulating the cache control bit(s)
Michael> in the MMU pages for a finer control (at a page leve).
>> I have no reference on any m68k MMU. Could you help me out,
>> describing what needs to be done for 68551, 68030 & 68040,
Tim> on the 030 (which is supposed to be a subset of the 68551 I
Tim> think) you just set the "Cache Inhibit" bit in page table entry
Tim> for the page in question. You can also set the Cache Inhibit in
Tim> any higher level tables to refer to all the pages under that
Tim> entry. The bit is PG_CI in the amiga/include/pte.h file.
Tim> (hmm.. the include only has defines for PG_CI and not SG_CI so
Tim> maybe the segment tables dont have a CI bit).
Great, now I just go to my code and add that bit... Hmm, it's already
there, has someone cracked into my NetBSD system and added this code
or is my subconsious mind much smarter than me? Nah, as always it was
MLH who beat me to the punch, by using that bit in the Z3 support that
I copied. Thanks Michael & Tim.
I'm now close to having a bridgecard framework together with a GoldenGateII
lower layer as well as the isa com driver ready. In order for you to taste
how it's used in a config file, look at this:
ggbus0 at ztwobus0
isabus0 at ggbus0
com0 at isabus0 port 0x3f8 irq 4
com1 at isabus0 port 0x2f8 irq 3
Neat, no? If we are lucky other bridgecards will have drivers written
to this framework, imagine the CrossLink:
clbus0 at ztwobus0
isabus0 at clbus0
then use the same device drivers as you would use for the GoldenGate.
For those of you with intelligent bridges like the A2386 and such,
you ought to be able to write some communication protocol in a likewise
bridge independent way, so it would work as an intelligent isa-bus
adapter fitting this framework. However, you have to do that yourself,
I'm not up to it for the moment.
I have good hopes to have the ed ethernet driver ported soon as well
as there is already a volunteer willing to help out. Are there other
volunteers for beta-testing and device driver porting? Contact me.