Re: [PATCH] arm64: dts: Fix GIC reg sizes for APM X-Gene

[Feng Kan <fkan@apm.com>]

On Wed, Mar 11, 2015 at 10:31 AM, Marc Zyngier <marc.zyngier@arm.com> wrote:
> On 11/03/15 17:19, Feng Kan wrote:
>> On Wed, Mar 11, 2015 at 7:53 AM, Marc Zyngier <marc.zyngier@arm.com> wrote:
>>> On 27/01/15 07:03, Pranavkumar Sawargaonkar wrote:
>>>> In APM X-Gene, GIC register space is 64K aligned while the sizes mentioned
>>>> in the dt are 4K aligned. This breaks KVM when kernel is built with 64K page
>>>> size due to size alignment checking in vgic driver for VCPU Control and
>>>> VCPU register.
>>>>
>>>> This patch corrects the sizes to be inline with the hardware spec.
>>>
>>> This patch may be correct, but it is useless. The firmware on my APM
>>> system (some version of u-boot) repaints the DT at boot time, negating
>>> the effect of this patch.
>> We have updated u-boot to reflect this change. I can supply you with a updated
>> image if you wish.
>
> That would be useful, thanks.
>
> But more importantly, why bother upstreaming your DT into the kernel
> tree if your firmware is going to overwrite whatever we provide?
We did tried to submit a version upstream but was rejected.

>
> Either the firmware let the user provide its own DT (and doesn't touch
> it other than to change the CPU enable method, insert a /memreserve/ or
> similar things), or the firmware always provide its own DT, and doesn't
> let the user provide its own. Corrupting the user DT is a disaster, as
> we just found.
Yes, the intent of the change is listed in the link below. It is not a
justification by any means,
just the effects of things appearing in layers.
http://lists.infradead.org/pipermail/linux-arm-kernel/2014-September/288574.html

>
> Thanks,
>
>         M.
>
>>>
>>> Another system I can remove from my 64k-capable list.
>>>
>>>         M.
>>>
>>>> CC: linux-arm-kernel@lists.infradead.org
>>>> CC: kvmarm@lists.cs.columbia.edu
>>>> CC: arnd@arndb.de
>>>> CC: marc.zyngier@arm.com
>>>> CC: christoffer.dall@linaro.org
>>>> CC: jcm@redhat.com
>>>> Signed-off-by: Pranavkumar Sawargaonkar <psawargaonkar@apm.com>
>>>> Signed-off-by: Tushar Jagad <tjagad@apm.com>
>>>> Signed-off-by: Feng Kan <fkan@apm.com>
>>>> ---
>>>>  arch/arm64/boot/dts/apm/apm-storm.dtsi |    8 ++++----
>>>>  1 file changed, 4 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/arch/arm64/boot/dts/apm/apm-storm.dtsi b/arch/arm64/boot/dts/apm/apm-storm.dtsi
>>>> index f1ad9c2..65f0e6d 100644
>>>> --- a/arch/arm64/boot/dts/apm/apm-storm.dtsi
>>>> +++ b/arch/arm64/boot/dts/apm/apm-storm.dtsi
>>>> @@ -81,10 +81,10 @@
>>>>               compatible = "arm,cortex-a15-gic";
>>>>               #interrupt-cells = <3>;
>>>>               interrupt-controller;
>>>> -             reg = <0x0 0x78010000 0x0 0x1000>,      /* GIC Dist */
>>>> -                   <0x0 0x78020000 0x0 0x1000>,      /* GIC CPU */
>>>> -                   <0x0 0x78040000 0x0 0x2000>,      /* GIC VCPU Control */
>>>> -                   <0x0 0x78060000 0x0 0x2000>;      /* GIC VCPU */
>>>> +             reg = <0x0 0x78010000 0x0 0x10000>,     /* GIC Dist */
>>>> +                   <0x0 0x78020000 0x0 0x20000>,     /* GIC CPU */
>>>> +                   <0x0 0x78040000 0x0 0x10000>,     /* GIC VCPU Control */
>>>> +                   <0x0 0x78060000 0x0 0x20000>;     /* GIC VCPU */
>>>>               interrupts = <1 9 0xf04>;       /* GIC Maintenence IRQ */
>>>>       };
>>>>
>>>> --
>>>> 1.7.9.5
>>>>
>>>>
>>>
>>>
>>> --
>>> Jazz is not dead. It just smells funny...
>>
>
>
> --
> Jazz is not dead. It just smells funny...