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Re: [Xen-users] What does viridian=1 do?



Am 31.08.2009 17:10, schrieb Matthieu Patou:
On 08/21/2009 02:15 PM, James Harper wrote:

Am 21.08.2009 04:23, schrieb James Harper:
So for faster IO you need GPLPV drivers.
I still would vote for further investigation and development on
viridian
enlighten IO. It would bring us out of the hell with driver signing,
and
would also make a lot of stuff easier from the users stand.
The work of James Harper is pretty good but for 2008 x64 more than
just
far away from ready for production.

Yes, definitely that would be good.

Feel free to start working on it :) I believe the needed viridian
interfaces
can be seen at least from linux hyper-v driver (linux-ic). Also
iirc ms
released some docs about the interfaces.


You are talking about reverse engineering a backend driver to match the
frontend driver in Linux. That would certainly be an interesting
project,
but
I wonder how Microsoft would feel about it :)

James

Uhm, James you have the best knowledge about this topic (the other way
around), would you say this is a real gap?

I'm not at all familiar with HyperV aside from a little bit of knowledge
about what viridian=1 does, and only then because viridian=1 crashed
gplpv
due to a bug in the way I had implemented my cpuid calls.

The point I was making is that Microsoft have provided the open source
drivers to better allow other operating systems to integrate with their
product. If you reverse engineer that to make their operating systems
work
better with xen then they might get a little bit upset... or they might
not... I'm not a Microsoft lawyer :)

Guessing how the otherside should behave is not for the faint of heart I
suppose. Ask the guys from samba on how they struggle to make samba a
Domain controller ...
Concerning upsetting Microsoft I don't see the problem that's what Samba
team is doing and there is a lot of project in the wild doing the same
with MS products and other products. Problem starts if you use patented
software methods (and well at least in US mainly for the moment as for
UE software patents are not valid).

I have 0 knowledge of HyperV technology but maybe the drivers for a
guest Windows into a Windows host are not by default installed in the
guest but proposed by the host to the guest in a similar way of how it
works with virtualbox or vmware (but it seems that starting from w2k8
this drivers are already installed ... is it true ? is it true also for
Windows 7 ?).

I found some documentation about the functional spec of HyperV
http://www.microsoft.com/downloads/details.aspx?FamilyID=91e2e518-c62c-4ff2-8e50-3a37ea4100f5&DisplayLang=en

Also some basic support is included into WinXP and 2003 R2 with latest servicepacks.

Florian
There may well be some technical limitations that prevent a HyperV
compatible backend layer being added to Xen... I don't know enough about
either to say.

If it could be done, then a whole lot of things would 'just work', and as
you say it could solve a lot of driver issues.

Or is the GPLPV-driver on the
way to fill it anyway soon, especially are there plans to get the
drivers signed? As I see it there wouldn't be any other proper solutions
for this topic.

I'm trying to fix a few bugs in the shutdown/suspend/resume/etc paths
at the
moment and it's proving a long and frustrating exercise, and I haven't
had a
lot of time to work on it lately.
Matthieu.

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