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Re: [microblaze-uclinux] [patch] memory management initialisationcleanup
Hi All,
Yasushi SHOJI wrote:
> At Mon, 02 Aug 2004 15:28:12 +1000,
> John Williams wrote:
>>Yasushi SHOJI wrote:
>>>John Williams wrote:
>>>>Not quite sure what you mean here - __pa() and __va() macros are already
>>>>defined for microblaze in asm-microblaze/page.h They just reduce to
>>>>identity functions of course since physical == virtual for nommu system.
>>>
>>>oops that was bad example. I just wanted to say that, because we only
>>>have physical address in microblaze right now, we don't need to use
>>>__phys_to_virt() and friends in arch/microblaze/*.
>>
>>I tend to feel that these things should stay in, even if they #define
>>down to nothing. It's like using copyfromuser() in uClinux device
>>drivers. You don't need to use it, and it translates to simple
>>memcpy(), but it's still good practice.
>
> Yes, it is good practice to have copy_from_user() in _device driver_,
> eventhough the device driver is only for mmu-less. you never know
> when the driver will be ported to other arch.
>
> however, because arch/microblaze/* depend to mmu-less cpu, we should
> have as clean code as we can. (well we need to define what _clean_
> means; i guess i'm a minimalis)
I wouldn't take any short cuts here. I would keep the code
in a fashion that allows an MMU to be added and still use
the existing code. If it can be added (and there is no real
reason it cannot) then someone will probably do it one day.
The trend in 2.6 with uClinux is that we coexist in the
architecture branch - so whether you have an MMU or not is no
more than a CONFIG_MMU define.
Regards
Greg
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