Re: [Xen-devel] Claim mode and HVM PoD interact badly

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 10.01.14 at 16:41, Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> wrote:
> On Fri, Jan 10, 2014 at 03:10:48PM +0000, Wei Liu wrote:
>> On Fri, Jan 10, 2014 at 09:58:07AM -0500, Konrad Rzeszutek Wilk wrote:
>> > --- a/tools/libxc/xc_hvm_build_x86.c
>> > +++ b/tools/libxc/xc_hvm_build_x86.c
>> > @@ -335,7 +335,12 @@ static int setup_guest(xc_interface *xch,
>> >  
>> >      /* try to claim pages for early warning of insufficient memory 
>> > available */
>> >      if ( claim_enabled ) {
>> > -        rc = xc_domain_claim_pages(xch, dom, nr_pages - cur_pages);
>> > +        unsigned long nr = nr_pages - cur_pages;
>> > +
>> > +        if ( pod_mode )
>> > +            nr = target_pages - 0x20;
>> > +
>> 
>> Yes it should work because this makes nr smaller than d->tot_pages and
>> d->max_pages. But according to the comment you pasted above this looks
>> like wrong fix...
> 
> It should be: 
> 
> tot_pages = 128MB
> max_pages = 256MB
> nr = 256MB - 0x20.
> 
> So tot_pages < max_pages > nr && nr > tot_pages
> 
> If I got my variables right.
> Which means that 'nr' is greater than tot_pages but less than max_pages.

But that seems conceptually wrong: As was said before, the guest
should only get 128Mb allocated, hence it would be wrong to claim
almost 256Mb for it.

Jan


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