https://bugs.freedesktop.org/show_bug.cgi?id=106601
--- Comment #12 from Yunchao He yunchao.he@intel.com --- (In reply to Ilia Mirkin from comment #9)
"Color-renderable" means "is it legal to use this format". It does NOT mean "the driver allows rendering to this format".
I am not a driver expert. But my understanding is that color-renderable means that we can render into this format as a color buffer. If color-renderable means "is it legal to use this format", then I can't explain these two questions as follows: 1. why we need to list that format which is illegal to use at all in spec? I suppose there are many formats for graphics/video. Enumerating formats that are not useful for texture (or renderbuffer) seems to be weird. 2. If color-renderable(or renderable) means that "is it legal to use this format" for a texture. Then that format is not allow to sample from. If so, how to distinguish these two kinds of formats: 1) some formats can be supported by a texture to sample only, they can't be used to render into as a render target via fbo, 2) some other formats can be supported by a texture to sample, and render into as well.
The statement that "Color-renderable means is it legal to use this format. It does NOT mean the driver allows rendering to this format" is correct for a renderbuffer, but I think it is incorrect for a texture. Because a renderbuffer is only used to render into, they can't be used to sample from. But this issue is talking about texture, NOT renderbuffer. Maybe for the underlying implementation, both texture and renderbuffer are mapped into the same GPU memory (or even CPU memory), but from the perspective of users, texture and renderbuffer are quite different.