[Xprint] Re: [Fwd: cfb conversion effort (was Re: Debugging X.org drivers?)]

[Stuart Kreitman]

we briefly toyed with porting m64 and vfb to use fb in Xsun.
It only took a few hours, and  it came up, but we didn't pursue it- not 
on our main path.

skk


Roland Mainz wrote:

>Hi!
>
>----
>
>I found the email which said that fb doesn't support some GC operation
>overiding...
>-- snip --
>Intermediate challenge would be something like sunleo or sunffb, where
>magic 
>GC handling is used to implement primitive acceleration - [...]  This is
>pretty
>gross and fb doesn't expose the same functionality;
>-- snip --
>... I didn't checked that in detail but it sounds like there would be a
>huge problem with converting the PCL drivers from cfb over to fb (or
>not... I didn't investigate that in detail yet... right now I stil don't
>dare to touch the PCL drivers in the hope that HP will contribute their
>drivers back to Xorg (changing the Xorg drivers may make the merging of
>the HP versions more difficult)) ... ;-(
>
>-------- Original Message --------
>Subject: cfb conversion effort (was Re: Debugging X.org drivers?)
>Date: Sun, 31 Oct 2004 02:07:14 -0400
>From: Adam Jackson <ajax at nwnk.net>
>To: xorg at freedesktop.org
>CC: Roland Mainz <roland.mainz at nrubsig.org>,Jim Gettys
><Jim.Gettys at hp.com>
>References: <41826D75.906.4AEE501E at localhost>
><200410301759.49970.ajax at nwnk.net> <418466A8.8AE9401F at nrubsig.org>
>
>On Sunday 31 October 2004 00:14, Roland Mainz wrote:
>  
>
>>Adam Jackson wrote:
>>    
>>
>>>Kendall, I'm for some reason thinking that the SciTech drivers were based
>>>on the cfb framebuffer core.  cfb will not work under dlloader with 6.8
>>>without a patch:
>>>
>>>http://freedesktop.org/bugzilla/show_bug.cgi?id=1114
>>>
>>>but you may be better off switching to fb.
>>>      
>>>
>>Do you have any example patch which shows how to turn a driver from cfb
>>over to fb ? HP's PCL drivers use cfb extensively and it may be nice to
>>switch them over, too...
>>    
>>
>
>Sure.  One trivial example is the RealVNC conversion patch Kristian
>Høgsberg 
>did: http://www.mail-archive.com/vnc-list@realvnc.com/msg14387.html
>
>For drivers that treat the fb layer as something of a black box, this is
>all 
>you need to do.  Most of the xfree86 ddx drivers are of this sort. 
>Until 
>fairly recently there was still optional cfb support in six of the
>drivers, 
>and http://freedesktop.org/bugzilla/show_bug.cgi?id=1192 shows the
>changes I 
>made to drop that support.  In all but s3virge this support was disabled
>at 
>compile time, and in s3virge the cfb code was slower and, as with cfb in 
>general, didn't support Render (and therefore Composite).
>
>Intermediate challenge would be something like sunleo or sunffb, where
>magic 
>GC handling is used to implement primitive acceleration - double
>entendre on 
>"primitive" totally intended.  This is pretty gross and fb doesn't
>expose the 
>same functionality; I suspect it can be dropped in most cases without
>too 
>much pain.  There's an experimental patch to convert sunleo to fb: 
>http://freedesktop.org/bugzilla/show_bug.cgi?id=1259
>which I have received no feedback on as of yet, and I don't have the
>hardware 
>to verify it.  sunffb is left as an exercise for the reader.
>
>The final step would be converting our overlay support to use fb.  I
>don't 
>even know where to begin here, largely for lack of hardware.  I see a
>couple 
>of functions in the fb layer that look like they're intended for overlay 
>support.  I've been tempted to just drop our overlay support altogether
>to 
>see who complains; my guess is, roughly, nobody.
>
>- ajax
>  
>