[Intel-gfx] [PATCH 2/4] drm: Create a format/modifier blob

[Ville Syrjälä]

On Fri, Jul 14, 2017 at 11:41:49AM -0700, Ben Widawsky wrote:
> On 17-06-29 22:49:44, Ville Syrjälä wrote:
> 
> [snip]
> 
> >
> >... but here it's ALIGN(formats_offset+formats_size). I think we should
> >be aligning the same thing in both cases, or we add a BUILD_BUG_ON to
> >make sure the header size always stays a multiple of 8 bytes.
> >
> >That's mainly because the design of the structure seems geared towards
> >expanding the header in the future (as in why else would you have the
> >offsets?).
> >
> 
> I guess I don't quite understand what you're asking for. The first thing is
> determining a size, the second is finding an offset into the blob.

If I remember my thinking correctly, then what I was trying to say was

ALIGN(multiple_of_4, 8) + ALIGN(multiple_of_4, 8) != ALIGN(multiple_of_4 + multiple_of_4, 8)

but the code was assuming that it's true, or that at least one of those
things is a multiple of 8 already.

> I don't mind changing this, but tell me what you want.
> 
> BUILD_BUG_ON sounds good to me regardless.
> 
> [snip]
> 
> -- 
> Ben Widawsky, Intel Open Source Technology Center

-- 
Ville Syrjälä
Intel OTC