From: Steve Rossi <srossi@ccrl•mot.com>
To: Dan Malek <dan@netx4•com>
Cc: Embedded Linux PPC List <linuxppc-embedded@lists•linuxppc.org>
Subject: Re: allocating non-cacheable regions
Date: Thu, 01 Jun 2000 08:01:44 -0500 [thread overview]
Message-ID: <39365EB8.427CD744@ccrl.mot.com> (raw)
In-Reply-To: 39358E65.145F7EA3@embeddededge.com
Dan Malek wrote:
>
> > .... How can I make it so that
> > reads as well as writes to a particular page bypass the cache?
>
> You need to invalidate the data cache for this address and the TLB
> entry for this address when you set the flag. Those drivers in your
> example get away with it because the caches/TLB have been invalidated
> and not yet touched at this point. You also need to ensure you are not
> multiple mapping the same physical address....
>
I'm invalidating the TLB entry via a call to flush_tlb_page as in the examples
that you pointed me to - which simply maps to tlbia on 8xx. But I haven't yet
figured out how to invalidate the data cache for the entire page. I'm trying
invalidate_dcache_range() - but I'm having really strange problems with it. If
I compile the driver into the kernel with a call to invalidate_dcache_range(),
the kernel won't boot. (It'll get as far as "Uncompressing Linux ..." and
it'll hang). The same happens if I export invalidate_dcache_range in
ppc_ksyms.c in an attempt to load the driver as a module. I haven't looked
into what is going on here - but I do know that it is being caused by the
invalidate_dcache_range being present. Am I totally off base here? Should
I even be using invalidate_dcache_range or is there another method for
invalidating the data cache? A pointer to an example would be sufficient if
anyone has one.
Thanks,
Steve
--
-------------------------------------------------------
Steven K. Rossi srossi@ccrl•mot.com
Staff Engineer
Multimedia Communications Research Laboratory
Motorola Labs
-------------------------------------------------------
** Sent via the linuxppc-embedded mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2000-06-01 13:01 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2000-05-03 15:47 allocating non-cacheable regions Steve Rossi
2000-05-03 19:52 ` Dan Malek
2000-05-04 6:45 ` MPC860 enet driver dony
2000-05-31 20:53 ` allocating non-cacheable regions Steve Rossi
2000-05-31 22:12 ` Dan Malek
2000-05-31 22:39 ` Tom Roberts
2000-06-01 13:01 ` Steve Rossi [this message]
2000-06-01 20:10 ` Steve Rossi
2000-06-02 14:24 ` Steve Rossi
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