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. 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. 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
