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From: Kumar Gala <galak@kernel.crashing.org>
Subject: Re: Discussion about iopa()
Date: Fri, 9 Feb 2007 16:46:57 -0600
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev list <linuxppc-dev@ozlabs.org>,
	Tabi Timur-B04825 <timur@freescale.com>
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On Feb 9, 2007, at 4:06 PM, Benjamin Herrenschmidt wrote:

> On Fri, 2007-02-09 at 12:13 -0500, Dan Malek wrote:
>> On Feb 8, 2007, at 4:26 PM, Benjamin Herrenschmidt wrote:
>>
>>> I'm really not fan of it.
>>
>> That's because I think it's a terribly useful function
>> and the first step toward some orthogonal VM APIs. :-)
>
> No, I think it's very inefficient to walk the page tables, even  
> worse if
> you have PTEs in HIGHMEM. I think it's better to keep track the  
> physical
> address from alloc time, something similar than dma_alloc_coherent but
> for use with that MURAM thingy.

My feeling is to leave the code alone until we have the dma mapping  
api setup to handle MURAM.  If we can't do alloc/map/free with the  
same mechanism I dont see the value in just doing 'map'.  It just  
makes the code more confusing w/o any big gain.

Truthfully the normal system memory size should be cleaned up to use  
the dma mapping API instead of straight allocations and mapping like  
its using now.

- k