Am 27.06.2010 um 11:50 schrieb Avi Kivity [off-list ref]:

On 06/27/2010 12:38 PM, Alexander Graf wrote:

quoted

Am 27.06.2010 um 10:16 schrieb Avi Kivity [off-list ref]:

quoted

On 06/26/2010 02:24 AM, Alexander Graf wrote:

quoted

One of the most obvious registers to share with the guest  
directly is the
MSR. The MSR contains the "interrupts enabled" flag which the  
guest has to
toggle in critical sections.

So in order to bring the overhead of interrupt en- and disabling  
down, let's
put msr into the shared page. Keep in mind that even though you  
can fully read
its contents, writing to it doesn't always update all state.  
There are a few
safe fields that don't require hypervisor interaction. See the  
guest
implementation that follows later for reference.

You mean, see the documentation for reference.

It should be possible to write the guest code looking only at the  
documentation.

*shrug* since we're writing open source I don't mind telling people  
to read code for a reference implemenration.

It's impossible to infer from the source what's a guaranteed part of  
the interface and what is just an implementation artifact.  So  
people rely on implementation artifacts (or even bugs) and that  
reduces our ability to change things.

quoted

If well written, that's more comprehensible than documentation  
anyways :).

If the documentation is poorly written, yes.

I think I start to agree. I guess i should just list all fields of the  
MSR that are ok to modify inside the guest context.

Alex