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

Anthony Liguori
2007-05-22T13:08:43Z

Eric Van Hensbergen wrote:
> On 5/22/07, Avi Kivity <avi-atKUWr5tajBWk0Htik3J/w@public.gmane.org> wrote:
>> Anthony Liguori wrote:
>> >>
>> >> In a PV environment why not just pass an initial cookie/hash/whatever
>> >> as a command-line argument/register/memory-space to the underlying
>> >> kernel?
>> >>
>> >
>> > You can't pass a command line argument to Windows (at least, not
>> easily
>> > AFAIK). You could get away with an MSR/CPUID flag but then you're
>> > relying on uniqueness which isn't guaranteed.
>> >
>>
>> In the general case, you can't pass a command line argument to Linux
>> either. kvm doesn't boot Linux; it boots the bios, which boots the boot
>> sector, which boots grub, which boots Linux. Relying on the user to
>> edit the command line in grub is wrong.
>>
>
> I didn't think we were talking about the general case, I thought we
> were discussing the PV case.

It is still useful to use PV drivers with full virtualization so it's
something that ought to be considered.

Regards,

Anthony Liguori

> In the PV case, having bios/bootloader
> is unnecessary overhead. To that same end, I don't see Windows in the
> PV case unless they magically want to to coordinate PV standards with
> us, in which case we certainly can negotiate a more sane discovery
> mechanism.
>
> -eric