Re: What is driverSwapMethod = DRI_HIDE_X_CONTEXT?

[Jon S. <jon...@gm...>]

I just changed DRM to alternative between zero and POLLIN.... This
will make the DRM poll() function work like the kernel expects it to
and still work with existing X servers. Can someone please get this
incorrect code out of the X server?

On Wed, 13 Oct 2004 16:39:27 +0100, Keith Whitwell
<ke...@tu...> wrote:
> Jon Smirl wrote:
> > On Wed, 13 Oct 2004 10:13:50 +0100, Keith Whitwell
> > <ke...@tu...> wrote:
> >
> >>Felix K=FChling wrote:
> >>I think the reason that you are experiencing failures is because the X =
server
> >>is trying to read or poll the drm filehandle, but Jon has recently chan=
ged the
> >>behaviour of that filehandle to return an error on those operations, ra=
ther
> >>than indicating that no bytes are pending.
> >>
> >>Let me stress that in most drivers there is no need for the X server to=
 be
> >>looking at this filehandle at all, but the code which does so is widely
> >>distributed and this change to the DRM will break it.
> >
> >
> > Is it the poll() call that is the problem? I can set it back to
> > returning zero. The kernel people are saying this is wrong and are
> > pushing me to have it return (POLLIN | POLLOUT | POLLRDNORM |
> > POLLWRNORM) which is the correct return for an unimplemented poll
> > function.
>=20
> In the very beginning, shared code in the X server listened to this fd, a=
nd
> shared code in the DRM existed to write to this fd, at the possible reque=
st of
> device-dependent DRM code.  The first DRM driver, the gamma, used this
> mechanism for context switching.  But no other DRM driver except perhaps =
ffb
> ever has.
>=20
> About 18 months ago, I recognized this and pushed the shared code into th=
e
> gamma driver, and removed the poll() and read() functions from drm_fops.h=
.
> Within the day I recognized that the X server continued to examine the fd=
, and
> that there was a need to restore empty poll() and read() functions.  Now =
that
> the gamma driver is dead, maybe we can go about pulling that behaviour ou=
t of
> the X server shared code as well.  But right now, you have a situation wh=
ere
> everybody running a DRI-enabled X server is dependent on the poll() (and =
maybe
> read()) function behaving in the way it always has.
>=20
> So, it's not really an unimplemented poll() function, but the
> backwards-compatible ghost of a real communications channel which is stil=
l
> polled, but never written to.
>=20
> Keith
>=20


--=20
Jon Smirl
jon...@gm...