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@xen.org>]

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@amazon.com>
>>>
>>> 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@amazon.com>
>>> Reported-by: Corey Minyard <minyard@acm.org>
>>> ---
>>>   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@mvista.com>
> 
> for all three patches.

Thank you for the testing! I will fix the bug and resend the series.

Cheers,

-- 
Julien Grall