Re: [Xen-devel] [PATCH 3/3] xen/arm: fix mask calculation in init_pdx

[Julien Grall <julien.grall@xxxxxxx>]

Hi Jan,

On 5/6/19 10:06 AM, Jan Beulich wrote:
> > > > On 03.05.19 at 22:50, <sstabellini@xxxxxxxxxx> wrote:
> > --- a/xen/arch/arm/setup.c
> > +++ b/xen/arch/arm/setup.c
> > @@ -481,10 +481,15 @@ static paddr_t __init next_module(paddr_t s, paddr_t *end)
> >   static void __init init_pdx(void)
> >   {
> >       paddr_t bank_start, bank_size, bank_end;
> > -
> > -    u64 mask = pdx_init_mask(bootinfo.mem.bank[0].start);
> > +    u64 mask;
> >       int bank;
> >   
> > +    /*
> > +     * We always map the first 1<<MAX_ORDER of RAM, hence, they are left
> "... pages of RAM." ?
>
> > +     * uncompressed.
> > +     */
> > +    mask = pdx_init_mask(1ULL << (MAX_ORDER + PAGE_SHIFT));
> PAGE_SIZE << MAX_ORDER?
Hmmm, I am not entirely convince this will give the correct value 
because PAGE_SIZE is defined as (_AC(1, L) << PAGE_SHIFT.
> I wonder whether pdx_init_mask() itself wouldn't better apply this
> (lower) cap
Do you mean always returning (PAGE_SIZE << MAX_ORDER) or capping the 
init mask?
Note that the later will not produce the same behavior as this patch.

Cheers,

--
Julien Grall

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