Raw device, raw device, raw device.
Look at Stephens code - its one step from O_DIRECT on a file working too, its
designed to do that next.
> > HDTV chipsets want capture to DMA 1600x1200x24bit data to memory targets.
> > The existing bttv sick 'vmalloc and look the other way' approach isnt as
> > good as locking pages for this (Disk I/O issues aside)
>
> Umm.. That's what I said. You can lock down pages _easily_ in the page
> cache. You just increment their usage count.
>
> And that has absolutely NOTHING to do with raw device access. What you do
> is you make "sendfile()" work for the "copy to page cache" case too.
Its only relevant because some of Stephens code also happens to do this. Im
quite happy to consider the two items seperately. And we do need DMA to locked
user pages (under kernel control!) for devices that generate a lot of data.
As Ingo pointed out I can then DMA to an mmap and sendfile the result if
I wish. This makes me happy.
Alan
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