Re: [Xen-devel] PVH dom0 creation fails - the system freezes

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Wed, Jul 25, 2018 at 06:29:25PM +0200, Juergen Gross wrote:
> On 25/07/18 18:12, Roger Pau Monné wrote:
> > On Wed, Jul 25, 2018 at 05:05:35PM +0300, bercarug@xxxxxxxxxx wrote:
> >> On 07/25/2018 05:02 PM, Wei Liu wrote:
> >>> On Wed, Jul 25, 2018 at 03:41:11PM +0200, Juergen Gross wrote:
> >>>> On 25/07/18 15:35, Roger Pau Monné wrote:
> >>>>>> What could be causing the available memory loss problem?
> >>>>> That seems to be Linux aggressively ballooning out memory, you go from
> >>>>> 7129M total memory to 246M. Are you creating a lot of domains?
> >>>> This might be related to the tools thinking dom0 is a PV domain.
> >>> Good point.
> >>>
> >>> In that case, xenstore-ls -fp would also be useful. The output should
> >>> show the balloon target for Dom0.
> >>>
> >>> You can also try to set the autoballoon to off in /etc/xen/xl.cfg to see
> >>> if it makes any difference.
> >>>
> >>> Wei.
> >> Also tried setting autoballooning off, but it had no effect.
> > 
> > This is a Linux/libxl issue that I'm not sure what's the best way to
> > solve. Linux has the following 'workaround' in the balloon driver:
> > 
> > err = xenbus_scanf(XBT_NIL, "memory", "static-max", "%llu",
> >                &static_max);
> > if (err != 1)
> >     static_max = new_target;
> > else
> >     static_max >>= PAGE_SHIFT - 10;
> > target_diff = xen_pv_domain() ? 0
> >             : static_max - balloon_stats.target_pages;
> 
> Hmm, shouldn't PVH behave the same way as PV here? I don't think
> there is memory missing for PVH, opposed to HVM's firmware memory.

There's memory missing for PVH, eg: the console page, the TSS for real
mode (if required), the identity page tables for running in
protected mode (if required) and the memory used to store the ACPI
tables.

Roger.

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/xen-devel