Re: [Xen-devel] [v2 10/11] log-dirty: refine common code to support PML

[Kai Huang <kai.huang@xxxxxxxxxxxxxxx>]

On 04/16/2015 11:51 PM, Jan Beulich wrote:
> > > > On 15.04.15 at 09:03, <kai.huang@xxxxxxxxxxxxxxx> wrote:
> > @@ -190,9 +196,15 @@ static int hap_enable_log_dirty(struct domain *d, bool_t 
> > log_global)
> >       d->arch.paging.mode |= PG_log_dirty;
> >       paging_unlock(d);
> >   
> > +    /* enable hardware-assisted log-dirty if it is supported */
> > +    p2m_enable_hardware_log_dirty(d);
> I don't see that you would anywhere avoid setting up software
> log-dirty handling - is that on purpose? If so, is there really a
> win from adding PML?
>
> >       if ( log_global )
> >       {
> > -        /* set l1e entries of P2M table to be read-only. */
> > +        /*
> > +         * switch to log dirty mode, either by setting l1e entries of P2M table
> > +         * to be read-only, or via hardware-assisted log-dirty.
> > +         */
> >           p2m_change_entry_type_global(d, p2m_ram_rw, p2m_ram_logdirty);
> Or did I miss you changing the behavior of this anywhere (as the
> changed comment suggests)?
Both of your comments are done in patch 11.

And I think even without patch 11, there's no harm with this patch as 
p2m_enable_hardware_log_dirty will essentially do nothing and write 
protection will be used for log-dirty :)
Thanks,
-Kai
> Jan
>
>
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