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Subject: Re: [PATCH 3/4] irqchip/mbigen: add support for a MBIGEN generating
 SPIs
To:     Hanjun Guo <guohanjun@huawei.com>,
        Yang Yingliang <yangyingliang@huawei.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Cc:     tglx@linutronix.de
References: <1539681316-19300-1-git-send-email-yangyingliang@huawei.com>
 <1539681316-19300-4-git-send-email-yangyingliang@huawei.com>
 <a8ea3f08-8d60-13bf-edcc-03298a9cfb0d@arm.com> <5BC800EB.5070201@huawei.com>
 <15c4ab00-3bfa-0eb8-a341-fc7a2be857f7@arm.com>
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From:   Marc Zyngier <marc.zyngier@arm.com>
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Organization: ARM Ltd
Message-ID: <223d7d7f-54b4-fd7f-1f83-95c9476136b7@arm.com>
Date:   Thu, 18 Oct 2018 12:56:35 +0100
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Sender: linux-kernel-owner@vger.kernel.org
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Hi Hanjun,

On 18/10/18 12:20, Hanjun Guo wrote:
> Hi Marc,
> 
>>>>>
>>>> Now, the biggest question of them all: how does it work with ACPI? Last
>>>> time I checked, there was no DT support for platforms using the MBIGEN.
>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/arm64/boot/dts/hisilicon/hip07.dtsi
>>> This DT describes how platform devices using the MBIGEN.
>>
>> That's not how my own D05 boots. It is ACPI only. How is that going to
>> work on this platform?
> 
> D05 is ACPI only so it has no dtb in the firmware, that's why we can
> boot D05 without acpi=on in the boot cmdline, but if you want to
> boot D05 with dtb, you could try to specify the dtb in the grub
> (seems centos based):
> 
> menuentry "example" --id example{
>         linux /Image-kernel root=... rdinit=...
>         initrd /example.img
>         devicetree /d05.dtb
> }

Sure. But what I'm asking here is how this change in the MBIGEN driver
can be beneficial to people who need ACPI, for better or worse? For
example, you cannot get the PCIe SMMU without ACPI. Good-bye VFIO.

If it is DT only, I seriously doubt anyone will be able to use it.

Thanks,

	M.
-- 
Jazz is not dead. It just smells funny...