On 04/08/2013 01:35:13 PM, Wolfgang Denk wrote:
Dear sun york-R58495,
In message
<c707e9f4d8007146bf8dc1424b113ac70b3a6...@039-sn2mpn1-012.039d.mgd.msft.net>
you wrote:
>
> I think it is best to keep this patch as it and stick with the
> original flush_cache name. It uses the existing function
> flush_cache() which is available for most (if not all)
architectures.
> Splitting the dcache and icache not only adds more code, but
> architecture-dependent code.
As mentioned before: reusing existing code is fine, but we already
have commands for cache handling, and adding arbitrary new ones to
implement combinations of functions makes does not scale. Assume
tomorrow someone needs to add more ganular handling for example
regarding L2 caches, etc. Would you suggest to add another set of new
commands, then? This makes no sense.
Maybe "cache" should be the toplevel command, with "icache" and
"dcache" refactored to be subcommands? Of course, then you're making
an incompatible interface change. How much is consistency worth?
Please implement IC related operations as subcommands to the "icache"
command, and DC releated ones as subcommands to "dcache".
The whole point of the patch is to expose the existing flush_cache()
functionality, which is not split into icache/dcache. From the user's
perspective, it's a command to flush the specified region out of *all*
caches. It's an implementation detail that some hardware or
architectures accomplish this using separate dcache and icache
instructions. If you make the interface be "icache/dcache", how would
you handle hardware where the flushing mechanism (or even the cache
itself) is not split?
[In the example of L2 cache above, it would be for example sufficient
to add a "-L2" option to the "icache" / "dcache" commands.]
Would it? On our chips L2 cache is (more or less) unified. There's no
separate icache/dcache flush.
-Scott
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