Re: [Xen-devel] VP problematic for backend drivers on IA64?

[Gerd Hoffmann <kraxel@xxxxxxx>]

  Hi,

> I think it's a pretty ugly hack; struct page has a very specific
> meaning in Linux. Minimizing changes in Linux by subverting this
> meaning does not strike me as the right thing to do.

Well, not exactly nice indeed, but any other solution involves touching
all block drivers ...

> at all - Linux is never going to look at the page (kmap it). Having

Depends.  If it's actually DMA'ing directly it doesn't, which should be
true in 99% of all cases.  But there are some corner cases:  If the
block layer needs bounce buffers it will attempt to kmap() the page to
copy the data.  The same is true for drivers which don't DMA (floppy.c
for example).

cheers,

  Gerd

-- 
Gerd 'just married' Hoffmann <kraxel@xxxxxxx>
I'm the hacker formerly known as Gerd Knorr.
http://www.suse.de/~kraxel/just-married.jpeg

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