Re: [PATCH/RFC 01/09] iommu/ipmmu-vmsa: Disable IPMMU when address expansion is not needed

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Magnus,

On Tue, Mar 19, 2019 at 2:45 PM Magnus Damm <magnus.damm@gmail.com> wrote:
> On Thu, Feb 21, 2019 at 1:10 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote:
> > On Wed, Feb 20, 2019 at 3:55 PM Magnus Damm <magnus.damm@gmail.com> wrote:
> > > --- 0001/drivers/iommu/ipmmu-vmsa.c
> > > +++ work/drivers/iommu/ipmmu-vmsa.c     2019-02-20 22:59:28.589893396 +0900
> >
> > > @@ -797,6 +798,12 @@ static bool ipmmu_slave_whitelist(struct
> > >         if (!soc_device_match(soc_rcar_gen3_whitelist))
> > >                 return false;
> > >
> > > +       /* In case all system memory fits within 32 bits of physical space
> > > +        * then assume the IPMMU will not be needed for address expansion.
> > > +        */
> > > +       if (memblock_end_of_DRAM() <= SZ_4G)
> >
> > Can this give a compiler warning on arm32 when CONFIG_ARM_LPAE=n?
>
> Not sure how, can you elaborate?

SZ_4G is 0x100000000ULL, which is always 64-bit.
memblock_end_of_DRAM() returns a physaddr_t, which is 32-bit if
CONFIG_ARM_LPAE=n, in which case the comparison is always true.

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds