Re: [PATCH for-4.14 3/3] xen/arm: plat: Allocate as much as possible memory below 1GB for dom0 for RPI

[Julien Grall <julien@xxxxxxx>]

Hi Corey,

On 19/05/2020 01:02, Corey Minyard wrote:
> On Mon, May 18, 2020 at 08:36:08PM +0000, Volodymyr Babchuk wrote:
> > Hi Julien,
> >
> > On Mon, 2020-05-18 at 12:30 +0100, Julien Grall wrote:
> > > From: Julien Grall <jgrall@xxxxxxxxxx>
> > >
> > > The raspberry PI 4 has devices that can only DMA into the first GB of
> > > the RAM. Therefore we want allocate as much as possible memory below 1GB
> > > for dom0.
> > >
> > > Use the recently introduced dma_bitsize field to specify the DMA width
> > > supported.
> > >
> > > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx>
> > > Reported-by: Corey Minyard <minyard@xxxxxxx>
> > > ---
> > >   xen/arch/arm/platforms/brcm-raspberry-pi.c | 1 +
> > >   1 file changed, 1 insertion(+)
> > >
> > > diff --git a/xen/arch/arm/platforms/brcm-raspberry-pi.c 
> > > b/xen/arch/arm/platforms/brcm-raspberry-pi.c
> > > index b697fa2c6c0e..ad5483437b31 100644
> > > --- a/xen/arch/arm/platforms/brcm-raspberry-pi.c
> > > +++ b/xen/arch/arm/platforms/brcm-raspberry-pi.c
> > > @@ -43,6 +43,7 @@ static const struct dt_device_match rpi4_blacklist_dev[] 
> > > __initconst =
> > >   PLATFORM_START(rpi4, "Raspberry Pi 4")
> > >       .compatible     = rpi4_dt_compat,
> > >       .blacklist_dev  = rpi4_blacklist_dev,
> > > +    .dma_bitsize    = 10,
> > I'm confused. Should it be 30?
> Indeed it should.  I just tested this series, and Linux fails to boot
> with this set to 10.  With it set to 30 it works.
>
> With this set to 30, you can have a:
>
> Tested-by: Corey Minyard <cminyard@xxxxxxxxxx>
>
> for all three patches.
Thank you for the testing! I will fix the bug and resend the series.

Cheers,

--
Julien Grall