Re: XVR-1000 (Re: pkgin missing on repo sparc64)

On Wed, 15 Jul 2020 13:59:49 +0200
Julian Coleman <[email protected]> wrote:

> In summary, there would be both a kernel part and a userland part
> (an X11 driver).  If a DRM driver exists, there is more logic in the
> kernel.  Otherwise, most of the logic is in the X11 driver.

OK thanks for the info. So if I understand it correctly:

DRI (x86 and arm) - X11 opens /dev/dri/card0 and then uses
various ioctls to set display mode and output graphics on the screen.
There is no direct access to graphics card memory and registers, i.e.
everything is abstracted via DRI ioctls.

Framebuffer (sparc64) - X11 mmap()s /dev/fb and has direct access to
graphics card memory and registers. There is no DRI or any other
common APIs, so to output graphics on the screen, X11 has to write to
mmap()ed memory regions.

So does this mean that from X11 point of view, with DRI there needs to
be just one user space driver, i.e. X11 talking to DRI? In this case the
DRI implements low-level drivers that actually talk to different
graphics cards, plus some user space library like libdrm, that provides
APIs for X11 and potentially translates C function calls into DRI
ioctls?