Re: [Xen-devel] PoD, 4.2, and current/maximum reservation

[James Harper <james.harper@xxxxxxxxxxxxxxxx>]

> >
> > As James said, this ought to run without xenbus having initialized
> > (so it can be done as early as possible). Hence the need for doing
> > this via hypercalls. The "classic" Xen balloon driver does so too, btw.
> >
> 
> We just use xenbus in the Citrix PV drivers and rely on the zero page sweep
> code in Xen to prevent a memory scrub from crashing the domain.
> 

I was using the difference between current_reservation and maximum_reservation 
but maximum_reservation doesn't appear to return the value in 4.2 that it did 
in 4.1 (based on one user report). current_reservation still appears to though 
so as long as I figure out how much physical memory is in the system (harder 
than it seems but a requirement even if you are using xenbus) I should be back 
in business.

> One problem with Windows can be SKU memory limits i.e. the OS cannot
> actually allocate from all the memory that is given to the domain so the 
> target
> cannot necessarily be met.
> 

Like giving memory=2GB, maxmem=6GB to an XP32 system and wondering why things 
don't work? I guess that's a case of don't do that :)

Windows has too many secrets.

James

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