Re: [Xen-devel] [PATCH for-4.5] libxl_set_memory_target: only remove videoram from absolute targets

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Wed, 3 Dec 2014, Konrad Rzeszutek Wilk wrote:
> On Wed, Dec 03, 2014 at 06:20:41PM +0000, Stefano Stabellini wrote:
> > If the new target is relative to the current target, do not remove
> > videoram again: it has already been removed from the current target.
> 
> Please explain:
>  - Is this an regression?

No, it is not.


>  - How often does it occur?

Every time the user creates a domain and memory needs to be freed in
dom0 for the allocation.


>  - Is it fatal?

No, it causes the new target for dom0 to be lower than it actually
needs to be by videram amount. However I realize now that the videoram
for dom0 is 0 so the bug wouldn't cause any troubles at the moment.

I guess it might be best to postpone this fix to 4.6.


>  - Are there work-arounds?
> 
> Thanks!
> > 
> > Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
> > 
> > diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
> > index de23fec..2aa83bd 100644
> > --- a/tools/libxl/libxl.c
> > +++ b/tools/libxl/libxl.c
> > @@ -4741,13 +4741,17 @@ retry_transaction:
> >          goto out;
> >      }
> >  
> > +    videoram_s = libxl__xs_read(gc, t, libxl__sprintf(gc,
> > +                "%s/memory/videoram", dompath));
> > +    videoram = videoram_s ? atoi(videoram_s) : 0;
> > +
> >      if (relative) {
> >          if (target_memkb < 0 && abs(target_memkb) > current_target_memkb)
> >              new_target_memkb = 0;
> >          else
> >              new_target_memkb = current_target_memkb + target_memkb;
> >      } else
> > -        new_target_memkb = target_memkb;
> > +        new_target_memkb = target_memkb - videoram;
> >      if (new_target_memkb > memorykb) {
> >          LIBXL__LOG(ctx, LIBXL__LOG_ERROR,
> >                  "memory_dynamic_max must be less than or equal to"
> > @@ -4763,9 +4767,6 @@ retry_transaction:
> >          abort_transaction = 1;
> >          goto out;
> >      }
> > -    videoram_s = libxl__xs_read(gc, t, libxl__sprintf(gc,
> > -                "%s/memory/videoram", dompath));
> > -    videoram = videoram_s ? atoi(videoram_s) : 0;
> >  
> >      if (enforce) {
> >          memorykb = new_target_memkb;
> > @@ -4780,7 +4781,6 @@ retry_transaction:
> >          }
> >      }
> >  
> > -    new_target_memkb -= videoram;
> >      rc = xc_domain_set_pod_target(ctx->xch, domid,
> >              new_target_memkb / 4, NULL, NULL, NULL);
> >      if (rc != 0) {
> 

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