[Mesa-dev] [PATCH] [RFC] mesa: propose simple EGL_MESA_image_dma_buf_export

[Daniel Stone]

Hi,

On 29 August 2014 08:46, Gwenole Beauchesne <gb.devel at gmail.com> wrote:

> Could you please describe in there the ownership model? I think the
> implementation should own the fd, so the clients should dup() it if
> ever necessary.
>

So the fd can be destroyed at any time, particularly with threads? Meaning
that if you want to use it, then the first thing you need to do before all
others, is to dup() it, but in theory it could be destroyed by then too ...

Much better to hand the client back something that it unambiguously owns,
where there's no possibility for interference. Note how
EGL_EXT_image_dma_buf_import was revised from the same shared
'implementation owns fd so client should dup() model', to one where the
implementation internally dup()s.


> Do we have a Query API for EGLImage? I thought that was for EGLSurface
> only. I mean, if not, that could be interesting to retrieve all the
> necessary other attributes, or extend the eglExportDMABufImageMESA()
> function to include the same level of information than what we have
> for EXT_image_dma_buf_import. e.g. multi-plane stride information for
> instance, up to including the actual format.
>
> What happens if the EGLImage is not backing a 2D texture?
>

Or TEXTURE_EXTERNAL, surely? Anyway, isn't that restriction a bit too
harsh, that the image has to be bound (or have been bound once?) to
TEXTURE_{2D,EXTERNAL}? Given how EGLImage is used as a neutral interchange
type/format in places, I think supporting dma_buf_import -> EGLImage ->
dma_buf_export, with no need to ever bind it to GLES texture units, is a
useful thing to have.

Cheers,
Daniel
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