Xref: utzoo unix-pc.general:2932 comp.sys.att:6526
Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uflorida!haven!umbc3!mark
From: mark@umbc3.UMBC.EDU (Mark Sienkiewicz)
Newsgroups: unix-pc.general,comp.sys.att
Subject: Re: resash of X-windows and 3b1/7300's
Message-ID: <2070@umbc3.UMBC.EDU>
Date: 23 May 89 02:14:19 GMT
References: <636@flatline.UUCP> <2067@umbc3.UMBC.EDU> <7972@zodiac.UUCP>
Reply-To: mark@umbc3.umbc.edu.UMBC.EDU (Mark Sienkiewicz)
Distribution: na
Organization: University of Maryland, Baltimore County
Lines: 40

The big agony of porting X to the unixpc has to do with trying to
just snarf an existing server.  Alex's networking port will probably
give us the networking end.  The problem I see immediately is this:

The sample servers seem to do 1 of two things:

1 - use an underlying graphics package to implement the root window.
I think the Apollo implementation does something like this.  Adapting
this approach to some other machine could be awfully time consuming.

2 - expect a bitmap of the screen to appear in the address space of
a user process.  This would involve either a spy at CT or a really
clever kernel hacker to find out how to work the paging stuff in the kernel.

I think a compromise could work like this:

Steal the mfb code.  Instead of operating directly on the bitmap, operate
on a copy.  As you modify it, flag the modified scan lines.  Periodically
copy the modified lines into the screen area by using a special system call.


Some less drastic (in my point of view, anyway) problems are:

- you are limited in CPU power.  You would gain a *** LOT *** of performance
by changing all the 32 bit operations to 16 bit operations.  This is a lot
of work which would probably be left out of a first stab at it.

- The are several megabytes of just server code to read.  Of course, you
can ignore most of it because it starts to all look alike, but sometimes
it is really interesting reading.

I am interested in hearing from anyone who wants to work on this.  I might
have tried it a long time ago, but I have a full time job, etc...


-- 
			Mark S.

uunet!umbc3!nerwin!zilla!mark
nerwin!zilla!mark@umbc3.umbc.edu