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Message-ID: <8eab6d63-1fa1-704f-279b-83b2df7fa808@arm.com>
Date:   Fri, 5 May 2023 15:53:54 +0100
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Subject: Re: [PATCH 1/3] iommu/dma: Clean up Kconfig
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To:     Jason Gunthorpe <jgg@nvidia.com>
Cc:     joro@8bytes.org, will@kernel.org, catalin.marinas@arm.com,
        jean-philippe@linaro.org, inki.dae@samsung.com,
        sw0312.kim@samsung.com, kyungmin.park@samsung.com,
        tglx@linutronix.de, maz@kernel.org, alex.williamson@redhat.com,
        cohuck@redhat.com, iommu@lists.linux.dev,
        linux-arm-kernel@lists.infradead.org, linux-acpi@vger.kernel.org,
        dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org,
        kvm@vger.kernel.org
References: <cover.1660668998.git.robin.murphy@arm.com>
 <2e33c8bc2b1bb478157b7964bfed976cb7466139.1660668998.git.robin.murphy@arm.com>
 <ZFUXmH9vndGZFuPr@nvidia.com>
From:   Robin Murphy <robin.murphy@arm.com>
In-Reply-To: <ZFUXmH9vndGZFuPr@nvidia.com>
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On 2023-05-05 15:50, Jason Gunthorpe wrote:
> On Tue, Aug 16, 2022 at 06:28:03PM +0100, Robin Murphy wrote:
>> Although iommu-dma is a per-architecture chonce, that is currently
>> implemented in a rather haphazard way. Selecting from the arch Kconfig
>> was the original logical approach, but is complicated by having to
>> manage dependencies; conversely, selecting from drivers ends up hiding
>> the architecture dependency *too* well. Instead, let's just have it
>> enable itself automatically when IOMMU API support is enabled for the
>> relevant architectures. It can't get much clearer than that.
>>
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>>   arch/arm64/Kconfig          | 1 -
>>   drivers/iommu/Kconfig       | 3 +--
>>   drivers/iommu/amd/Kconfig   | 1 -
>>   drivers/iommu/intel/Kconfig | 1 -
>>   4 files changed, 1 insertion(+), 5 deletions(-)
>>
>> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
>> index 571cc234d0b3..59af600445c2 100644
>> --- a/arch/arm64/Kconfig
>> +++ b/arch/arm64/Kconfig
>> @@ -209,7 +209,6 @@ config ARM64
>>   	select HAVE_KPROBES
>>   	select HAVE_KRETPROBES
>>   	select HAVE_GENERIC_VDSO
>> -	select IOMMU_DMA if IOMMU_SUPPORT
>>   	select IRQ_DOMAIN
>>   	select IRQ_FORCED_THREADING
>>   	select KASAN_VMALLOC if KASAN
>> diff --git a/drivers/iommu/Kconfig b/drivers/iommu/Kconfig
>> index 5c5cb5bee8b6..1d99c2d984fb 100644
>> --- a/drivers/iommu/Kconfig
>> +++ b/drivers/iommu/Kconfig
>> @@ -137,7 +137,7 @@ config OF_IOMMU
>>   
>>   # IOMMU-agnostic DMA-mapping layer
>>   config IOMMU_DMA
>> -	bool
>> +	def_bool ARM64 || IA64 || X86
> 
> Robin, do you remember why you added IA64 here? What is the Itanimum
> IOMMU driver?

config INTEL_IOMMU
	bool "Support for Intel IOMMU using DMA Remapping Devices"
	depends on PCI_MSI && ACPI && (X86 || IA64)

Yes, really :)

Robin.