Re: [Xen-devel] [RFC] [0/4] User-space grants for Console and XenStore

[Derek Murray <Derek.Murray@xxxxxxxxxxxx>]

On 2 May 2007, at 13:46, Keir Fraser wrote:

> It should be easy to support the old way and choose dynamically at  
> run time.
> We should somehow tag the values passed to or stored in xenstore  
> explicitly
> as being grant-refs, at the very least.
At present, I don't store the grant-refs in xenstore, because they  
are constant (always 0 for xenstore, 1 for the console). I suppose I  
can see an argument where two different tool stacks are used with  
different conventions, but the same console and xenstore daemons are  
used. The tricky part is getting the grant references out of the  
domain builder without changing the interface to xc_linux_build().  
Would it be reasonable to assume that the current versions of xend  
and libxc are consistent, and therefore the fixed grant references  
could be written into xenstore (from constants in the Python code) at  
the same time as the console and xenstore mfns are?
> I would like to continue to avoid dependence on particular dom0 kernel
> features, so new tool stack on old kernel (with no gnttab driver)  
> should
> really continue to work.
This should be quite simple: if the call to xc_gnttab_open() fails,  
it could set a flag which determines the method to be used. All that  
needs to be done in the mean time is to add stub functions to  
xc_solaris.c - I'll do that.
Regards,

Derek.


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