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Re: [PATCH v4] xen/arm: Allow QEMU platform to be built with GICv2


  • To: Dongjiu Geng <gengdongjiu1@xxxxxxxxx>
  • From: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>
  • Date: Mon, 17 Jan 2022 11:38:33 +0000
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  • Delivery-date: Mon, 17 Jan 2022 11:39:04 +0000
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  • Thread-topic: [PATCH v4] xen/arm: Allow QEMU platform to be built with GICv2

Hi,

> On 17 Jan 2022, at 11:12, Dongjiu Geng <gengdongjiu1@xxxxxxxxx> wrote:
> 
> Bertrand Marquis <Bertrand.Marquis@xxxxxxx> 于2022年1月17日周一 17:00写道:
>> 
>> Hi,
>> 
>>> On 17 Jan 2022, at 06:40, Dongjiu Geng <gengdongjiu1@xxxxxxxxx> wrote:
>>> 
>>> It turns out that QEMU has been supporting GICv2 virtualization since
>>> v3.1.0. So remove the dependencies on GICv3. If we want to use GICv3,
>>> we can select the QEMU_LEGACY configuration.
>> 
>> I am bit puzzled by this change introducing a legacy option actually 
>> selecting the newest GIC interface.
>> 
>> Can’t we do the opposite and introduce a QEMU_GICV2 instead ?
>> 
>> Also why do we need to remove gic-v3 support ? The code should actually 
>> select which gic to use depending on the device tree.
> 
> QEMU platfrom only select GICv3,  so I remove this limitation,  let
> user or developer selects gic version is better.

This is where I am lost, the code is actually always compiling gic-v2 support 
in unless new vgic is selected (see arch/arm/Makefile).

Cheers
Bertrand

> 
>> 
>> Regards
>> Bertrand
>> 
>>> 
>>> Signed-off-by: Dongjiu Geng <gengdongjiu1@xxxxxxxxx>
>>> ---
>>> xen/arch/arm/platforms/Kconfig | 10 +++++++++-
>>> 1 file changed, 9 insertions(+), 1 deletion(-)
>>> 
>>> diff --git a/xen/arch/arm/platforms/Kconfig b/xen/arch/arm/platforms/Kconfig
>>> index c93a6b2756..41e82a42ee 100644
>>> --- a/xen/arch/arm/platforms/Kconfig
>>> +++ b/xen/arch/arm/platforms/Kconfig
>>> @@ -13,7 +13,15 @@ config ALL_PLAT
>>>      automatically select any of the related drivers.
>>> 
>>> config QEMU
>>> -     bool "QEMU aarch virt machine support"
>>> +     bool "QEMU aarch virt machine support >= v3.1.0"
>>> +     depends on ARM_64
>>> +     select HAS_PL011
>>> +     ---help---
>>> +     Enable all the required drivers for QEMU aarch64 virt emulated
>>> +     machine.
>>> +
>>> +config QEMU_LEGACY
>>> +     bool "QEMU aarch virt machine support < v3.1.0"
>>>      depends on ARM_64
>>>      select GICV3
>>>      select HAS_PL011
>>> --
>>> 2.25.1


 


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