Re: [PATCH/RFC 7/9] Virtual network guest device driver

ron minnich
2007-05-22T17:00:42Z

On 5/22/07, Eric Van Hensbergen <ericvh-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:

> I'm not opposed to supporting emulation environments, just don't make
> a large pile of crap the default like Xen -- and having to integrate
> PCI probing code in my guest domains is a large pile of crap.

Exactly. I'm about to start a pretty large project here, using xen or
kvm, not sure. One thing for sure, we are NOT going to use anything
but PV devices. Full emulation is nice, but it's just plain silly if
you don't have to do it. And we don't have to do it. So let's get the
PV devices right, not try to shoehorn them into some framework like
PCI.

What happens to these schemes if I want to try, e.g., 2^16 PV devices?
Or some other crazy thing that doesn't play well with PCI -- simple
example -- I want a 256 GB region of memory for a device. PCI rules
require me to align it on 256GB boundaries and it must be contiguous
address space. This is a hardware rule, done for hardware reasons, and
has no place in the PV world. What if I want a bit more than the basic
set of BARs that PCI gives me? Why would we apply such rules to a PV?
Why limit ourselves this early in the game?

thanks

ron