Re: [PATCH 6/6] virtio ring helper

Rusty Russell
2007-09-23T11:40:07Z

On Sun, 2007-09-23 at 12:05 +0200, Avi Kivity wrote:
> Rusty Russell wrote:
> > On Thu, 2007-09-20 at 14:43 +0200, Avi Kivity wrote:
> >> 32 bits of page numbers give 44 bits of physical address on x86. That's
> >> 16TB per guest. Admittedly it's smaller on a VAX.
> >
> > I like to feel that I make these mistakes to ensure others are paying
> > attention. However, it does mean that I can just put an address in
> > there and increase the length field to 32 bits. Much rejoicing.
> >
>
> Why are we sending page numbers anyway? See below.

Perhaps I was unclear. I already changed to a 64-bit address. I
haven't send out another set of patches because I'm changing to Arnd's
explicit virtio bus too. Will send out a new set tomorrow at this rate.

> Where one of the flags is VRING_DESC_INDIRECT, which means that the
> memory within (address, length) is a bunch of descriptors instead of raw
> data.

If that's all we wanted, it's fairly easy to do as a future extension
even if we didn't change it today. My concern was the allocation and
management of those sg pages; hence my desire for a patch 8)

Rusty.