Re: RFC: being more anal about iospace accesses..

[Matthew Wilcox <willy@debian.org>]

On Wed, Sep 15, 2004 at 09:28:01PM -0700, Linus Torvalds wrote:
> Indeed. Once created, the cookie is "bus-agnostic", which is very much the 
> point. Unlike the original pci DMA interfaces, there are no real bus 
> assumtions in the interfaces once set up. 

In designing the new iomap interface for PA, I noticed a problem.

2004/09/14 torvalds   |  * They do _not_ update the port address. If you
2004/09/14 torvalds   |  * want MMIO that copies stuff laid out in MMIO
2004/09/14 torvalds   |  * memory across multiple ports, use "memcpy_toio()"
2004/09/14 torvalds   |  * and friends.

That implies you can pass an iomap cookie to memcpy_toio(), which makes
designing the iomap interface significantly harder.  Could I ask for
iocopy_to(), iocopy_from() and ioset() interfaces too?

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain