RE: [Xen-devel] help to understand is_running _on_xen ?

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> Gautham Kampalapur Shankar, TLS, Chennai
> Sent: 04 June 2007 16:05
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Subject: [Xen-devel] help to understand is_running _on_xen ?
> 
> 
>    I don't  understand why we check this condition 
> is_running_on_xen  ?In all drivers(front & back) code we are 
> checking this condition ?what is this function stands for ? 
> what it does ?

If you search for "is_running_on_xen" in the Linux tree, you'll find
that the x86 definition of this is "1" - so any test for this,
currently, means that it's "true". IA64 is different, at least in the
exact implementation. 

I can't explain this in any othe way than that the plan is to allow for
drivers to check if they are running on a native platform or running on
top of Xen, and make decisions (such as "not attempt to make
hypercalls") based on which case it is - so if we're not running on Xen,
don't make hypercalls to Xen, because it wont work!

--
Mats
> 
> 



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