Re: [PATCH for-4.5 v2 2/2] xen: arm: Enable physical address space compression (PDX) on arm32

[Ian Campbell <ian.campbell@citrix.com>]

On Fri, 2014-09-12 at 16:00 -0700, Julien Grall wrote:
> > +/* Sets all bits from the most-significant 1-bit down to the LSB */
> > +static u64 __init fill_mask(u64 mask)
> > +{
> > +    while (mask & (mask + 1))
> > +        mask |= mask + 1;
> > +    return mask;
> > +}
> 
> The function is the same on x86. Shall we create an helper?

I'll see what I can do.

> > diff --git a/xen/include/asm-arm/config.h b/xen/include/asm-arm/config.h
> > index 1c3abcf..59b2887 100644
> > --- a/xen/include/asm-arm/config.h
> > +++ b/xen/include/asm-arm/config.h
> > @@ -126,7 +126,12 @@
> >   #define CONFIG_SEPARATE_XENHEAP 1
> >
> >   #define FRAMETABLE_VIRT_START  _AT(vaddr_t,0x02000000)
> > -#define VMAP_VIRT_START  _AT(vaddr_t,0x10000000)
> > +#define FRAMETABLE_SIZE        MB(128-32)
> 
> I would add a comment about why the frametable size is "MB(128-32)".

There is a big comment just above here which gives an overview of the
virtual address space layout. I don't think it needs repeating here.

Ian.