[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [RFC PATCH v3 2/6] swiotlb: Add restricted DMA pool
On Thu, Jan 07, 2021 at 10:09:14AM -0800, Florian Fainelli wrote: > On 1/7/21 9:57 AM, Konrad Rzeszutek Wilk wrote: > > On Fri, Jan 08, 2021 at 01:39:18AM +0800, Claire Chang wrote: > >> Hi Greg and Konrad, > >> > >> This change is intended to be non-arch specific. Any arch that lacks DMA > >> access > >> control and has devices not behind an IOMMU can make use of it. Could you > >> share > >> why you think this should be arch specific? > > > > The idea behind non-arch specific code is it to be generic. The devicetree > > is specific to PowerPC, Sparc, and ARM, and not to x86 - hence it should > > be in arch specific code. > > In premise the same code could be used with an ACPI enabled system with > an appropriate service to identify the restricted DMA regions and unlock > them. Which this patchset is not. > > More than 1 architecture requiring this function (ARM and ARM64 are the > two I can think of needing this immediately) sort of calls for making > the code architecture agnostic since past 2, you need something that scales. I believe the use-case is for ARM64 at this moment. > > There is already code today under kernel/dma/contiguous.c that is only > activated on a CONFIG_OF=y && CONFIG_OF_RESERVED_MEM=y system, this is > no different. > -- > Florian
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