Messages in this thread | | | Subject | Re: DMA Engine: Transfer From Userspace | From | Dave Jiang <> | Date | Wed, 24 Jun 2020 17:42:24 -0700 |
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On 6/21/2020 12:24 AM, Vinod Koul wrote: > On 19-06-20, 16:31, Dave Jiang wrote: >> >> >> On 6/19/2020 3:47 PM, Federico Vaga wrote: >>> Hello, >>> >>> is there the possibility of using a DMA engine channel from userspace? >>> >>> Something like: >>> - configure DMA using ioctl() (or whatever configuration mechanism) >>> - read() or write() to trigger the transfer >>> >> >> I may have supposedly promised Vinod to look into possibly providing >> something like this in the future. But I have not gotten around to do that >> yet. Currently, no such support. > > And I do still have serious reservations about this topic :) Opening up > userspace access to DMA does not sound very great from security point of > view.
What about doing it with DMA engine that supports PASID? That way the user can really only trash its own address space and kernel is protected.
> > Federico, what use case do you have in mind? > > We should keep in mind dmaengine is an in-kernel interface providing > services to various subsystems, so you go thru the respective subsystem > kernel interface (network, display, spi, audio etc..) which would in > turn use dmaengine. >
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