[Mesa-dev] [PATCH] gbm: Add gbm_bo_write entry point

[Jakob Bornecrantz]

----- Original Message -----
> On Thu, May 3, 2012 at 5:08 PM, Mandeep Baines
> <mandeep.baines at gmail.com> wrote:
> > 2012/5/2 Kristian Høgsberg <krh at bitplanet.net>:
> >> This new gbm entry point allows writing data into a gbm bo.  The
> >> bo has to be created with the GBM_BO_USE_WRITE flag, and it's
> >> only required to work for GBM_BO_USE_CURSOR_64X64 bos.
> >>
> >> The gbm API is designed to be the glue layer between EGL and KMS,
> >> but there was never a mechanism initialize a buffer suitable for
> >> use with KMS hw cursors.  The hw cursor bo is typically not
> >> compatible with anything EGL can render to, and thus there's no
> >> way to get data into such a bo.
> >>
> >
> > Hi Kristian,
> >
> > What is the advantage of this approach over just using dumb buffers
> > via DRM_IOCTL_MODE_CREATE_DUMB and
> > DRM_IOCTL_MODE_MAP_DUMB?
> 
> Those are DRM ioctls.  gbm is a drm independent API and can work for
> non-drm/mesa EGL stacks.

Couldn't we just say that GBM doesn't do cursors and its up to what
ever API you use to do modesetting to do it in (eg KMS/DRM)?

It would make the st/dri code not have to depend on libkms or pollute
gallium drivers with cursors, which in the case of SVGA isn't handled
all that to well. But improving it would add a bunch of extra code.

Cheers, Jakob.