GstMemory Flags

Nicolas Dufresne nicolas at
Fri Nov 30 00:35:35 UTC 2018

Le jeu. 29 nov. 2018 15 h 14, Stirling Westrup <swestrup at> a
écrit :

> I'm in the middle of implementing a new type of GstMemory and would
> like some clarification on the intended meaning of the
> GST_MEMORY_IS_PHYSICALLY_CONTIGUOUS flag. The help text essentially
> just repeats what the flag already says, and ignores the fact that any
> piece of allocated memory represented by a single address is
> NECESSARILY physically contiguous. So the flag appears to be
> inherently useless (and indeed, it appears completely unused in the
> gstreamer sources).
> My only guess at a likely meaning is that it marks the memory as being
> part of a larger contiguous piece of allocated memory, but without
> additional associated information, this would appear to be of no use,
> especially considering that GstMemory already has a mechanism to
> handle this very thing, using the size and offset fields.
> So, what is the flag intended to indicate?

It was meant to announce if memory is contiguous in physical memory.
Information known with NXP Freescale vendoe stack, but not generally
available for Linux CMA allocation. In general, you should not need it.

> --
> Stirling Westrup
> Programmer, Entrepreneur.
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