Re: A question of grant table version

[Ian Campbell <Ian.Campbell@citrix.com>]

On Sat, 2011-04-09 at 02:28 +0100, hotmaim wrote:
> Hi
> 
> I have a question on grant table version.
> In 2.6.31 pvops kernel, there is a gnttab_request_version to request using version 2.
> But this cannot be found in 2.6.3236 pvops kernel, that is it uses version 1.
> 
> So, the fact is newer kernel use older grant table version, it doesn,t make sense to me.
> Could someone comfirm it is on purpose?

Unless you specifically need the new functionality of grant table v2
(transitive grants or sub page grants) there is no difference/benefit
between v1 and v2.

The only user of that new functionality was netchannel2, which has not
been carried forward from 2.6.31 and hence current kernels still use v1
grant tables with no loss of functionality.

People are working on introducing the interesting features of
netchannel2 as protocol extensions to netchannel1 and it is likely that
this will also involve reintroducing the use of grant table v2 in newer
kernels.

Ian.