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To: "Adam J. Richter" <adam@yggdrasil.com>
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Subject: Re: [parisc-linux] Untested port of parisc_device to generic device 
 interface
In-Reply-To: Message from "Adam J. Richter" <adam@yggdrasil.com> 
   of "Sat, 09 Nov 2002 16:23:59 PST." <200211100023.QAA27139@baldur.yggdrasil.com> 
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From: "J.E.J. Bottomley" <James.Bottomley@steeleye.com>
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adam@yggdrasil.com said:
> 
> 	I'd like to know more about what these machines look like in the real
> world.  Specifically, I am interested in the trade-off of having a
> parameter to wback_fake_consistent so that it could be enabled or
> disabled on an individual basis.

Actually, so would I.  I can suspect why there might exist machines like this 
(say the consistent attribute is settable at the pgd level)

> 	I suspect that the parameter is not worth the clutter because these
> "partially consistent" machines either have a large amount of
> consistent memory, so the case of the allocation failing in the is not
> worth supporting, or it is easy to check for consistent memory on them
> with something like "if ((unsigned long) vaddr < 0xwhatever)", but I'm
> just guessing. 

Well, if it has to be done, it can be done by making alloc_consistent return a 
handle rather than an address and making wback/invalidate take the handle (but 
it's certainly not ideal).

James


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