Messages in this thread | | | Subject | Re: [PATCH v8 1/6] drm/fourcc: Add modifier definitions for describing Amlogic Video Framebuffer Compression | From | Neil Armstrong <> | Date | Thu, 2 Jul 2020 15:34:40 +0200 |
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On 02/07/2020 15:18, Daniel Vetter wrote: > On Thu, Jul 02, 2020 at 09:23:11AM +0000, Simon Ser wrote: >> On Thursday, July 2, 2020 9:47 AM, Neil Armstrong <narmstrong@baylibre.com> wrote: >> >>> Finally is also adds the Scatter Memory layout, meaning the header contains IOMMU >>> references to the compressed frames content to optimize memory access >>> and layout. >>> >>> In this mode, only the header memory address is needed, thus the content >>> memory organization is tied to the current producer execution and cannot >>> be saved/dumped neither transferrable between Amlogic SoCs supporting this >>> modifier. >> >> Still not sure how to handle this one, since this breaks fundamental >> assumptions about modifiers. > > I wonder whether we should require special allocations for these, and then > just outright reject mmap on these buffers. mmap on dma-buf isn't a > required feature.
Yes, it's the plan to reject mmap on these buffers, but it can't be explained in the modifiers description and it's a requirement of the producer, not the consumer.
> > That would make sure that userspace cannot look at them. > > Also I'm kinda suspecting that there's not unlimited amounts of this magic > invisible storage available anyway. > -Daniel >
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