On Thu, Jul 02, 2020 at 09:23:11AM +0000, Simon Ser wrote:

On Thursday, July 2, 2020 9:47 AM, Neil Armstrong [off-list ref] wrote:

quoted

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.

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
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch

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