[Intel-gfx] [PATCH 2/3] drm: Create a format/modifier blob

[Daniel Vetter]

On Wed, May 17, 2017 at 1:31 PM, Daniel Vetter <daniel at ffwll.ch> wrote:
> On Tue, May 16, 2017 at 02:19:12PM -0700, Ben Widawsky wrote:
>> On 17-05-03 17:08:27, Daniel Vetter wrote:
>> > On Tue, May 02, 2017 at 10:14:27PM -0700, Ben Widawsky wrote:
>> > > +struct drm_format_modifier_blob {
>> > > +#define FORMAT_BLOB_CURRENT 1
>> > > + /* Version of this blob format */
>> > > + u32 version;
>> > > +
>> > > + /* Flags */
>> > > + u32 flags;
>> > > +
>> > > + /* Number of fourcc formats supported */
>> > > + u32 count_formats;
>> > > +
>> > > + /* Where in this blob the formats exist (in bytes) */
>> > > + u32 formats_offset;
>> > > +
>> > > + /* Number of drm_format_modifiers */
>> > > + u32 count_modifiers;
>> > > +
>> > > + /* Where in this blob the modifiers exist (in bytes) */
>> > > + u32 modifiers_offset;
>> > > +
>> > > + /* u32 formats[] */
>> > > + /* struct drm_format_modifier modifiers[] */
>> > > +} __packed;
>> >
>> > The struct should be in the uapi header. Otherwise it won't show up in
>> > libdrm headers when following the proper process.
>> > -Daniel
>> >
>>
>> I don't agree that blobs are ever really part of the API, but it doesn't hurt to
>> move it... in other words, done.
>
> Userspace writes them, the kernel reads them (or maybe even the other way
> round). How exactly is a specific blob and its layout not part of uapi?
> Can you explain your reasoning here pls?

Ok, this is the other way round, kernel writes this, userspace reads
it. Question still stands.
-Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch