Re: [PATCH 02/28] ARM: GICv3 ITS: parse and store ITS subnodes from hardware DT

[Julien Grall <julien.grall@arm.com>]

On 27/02/17 11:43, Andre Przywara wrote:
> Hi,

Hi Andre,

> On 06/02/17 12:58, Julien Grall wrote:
>> Hi Andre,
>>
>> On 30/01/17 18:31, Andre Przywara wrote:
>>> Parse the DT GIC subnodes to find every ITS MSI controller the hardware
>>> offers. Store that information in a list to both propagate all of them
>>> later to Dom0, but also to be able to iterate over all ITSes.
>>> This introduces an ITS Kconfig option.
>>>
>>> Signed-off-by: Andre Przywara <andre.przywara@arm.com>
>>> ---
>>>  xen/arch/arm/Kconfig             |  4 +++
>>>  xen/arch/arm/Makefile            |  1 +
>>>  xen/arch/arm/gic-v3-its.c        | 71
>>> ++++++++++++++++++++++++++++++++++++++++
>>>  xen/arch/arm/gic-v3.c            | 12 ++++---
>>>  xen/include/asm-arm/gic_v3_its.h | 57 ++++++++++++++++++++++++++++++++
>>>  5 files changed, 141 insertions(+), 4 deletions(-)
>>>  create mode 100644 xen/arch/arm/gic-v3-its.c
>>>  create mode 100644 xen/include/asm-arm/gic_v3_its.h
>>>
>>> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig
>>> index 2e023d1..bf64c61 100644
>>> --- a/xen/arch/arm/Kconfig
>>> +++ b/xen/arch/arm/Kconfig
>>> @@ -45,6 +45,10 @@ config ACPI
>>>  config HAS_GICV3
>>>      bool
>>>
>>> +config HAS_ITS
>>> +        bool "GICv3 ITS MSI controller support"
>>> +        depends on HAS_GICV3
>>
>> Should not this be disabled by default until the last patch of the
>> series in order to avoid potential issue if bisecting Xen?
>
> It should work without it, as we only ever map something driven by Dom0,
> which does not learn about the virtual until the very last patch.
> Actually enabling it early on allows fine-grained build and runtime
> testing and bisecting, so we can pinpoint breakages in the VGIC
> subsystem to a particular patch.
>
> So do you see any real issues with that? Or was that just a feeling?

Just a feeling. If you say it should be ok, then I am happy with that.

Cheers,

-- 
Julien Grall

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