Re: [Xen-devel] Insane contiguous physical memory requirements in blkbk/blktap

["Stephen C. Tweedie" <sct@xxxxxxxxxx>]

Hi,

On Thu, 2006-10-05 at 17:19 +0100, Keir Fraser wrote:

> >> This is easily fixable. Anywhere we use the virtual address to compute an
> >> offset into a state structure, we can instead store the appropriate 'slot
> >> index' in a spare field in the appropriate 'struct page'.

> I'm thinking of netback. That's the one driver where I think we use a
> virtual address (actually page-struct pointer) as a handle to
> driver-internal state.

OK, I was looking at blkback in this case.  Indexing is easy, we already
have page->index for that purpose, and I don't think there's anything
else using that for these pages once they are detached from the main VM.

Is there any reason we're not using memory in the vmalloc area for these
things?  That memory is *supposed* to be allocated out for virtual use
on demand.

--Stephen



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