Re: Building XServer

[Johnny Billquist <bqt%softjar.se@localhost>]

On 10/07/10 15:02, der Mouse wrote:
> [top-posting damage repaired manually]
>    

That's ok. I randomly top-post or post inline nowadays, on what I think 
others in the thread might be doing. I'll happily switch, since I don't 
have a strong preference for either, except when discussions become 
complex and intervowen, at which point top posting just don't work. :-)

> > > finally i built a xserver for my VAXStation 4000/90.  But it causes
> > > the kernel to dump core (well, on vax it actually doesn't...).
> > >        
> That probably indicates a kernel bug, I'd say; unless the server is
> doing something dodgy like mucking about with /dev/mem, it shouldn't be
> capable of panicking the kernel.
>
> Your stack trace makes it look like a bug in the spx driver, at a
> five-second glance.  I can't say much more, because both your OS and
> your X are versions I've never played with at all, much less on a VAX.
>
>    

I thought the X server did poke in /dev/mem or similar, since it probes 
and plays with the hardware rather direct. It also tries to find the PCI 
memory mapping (or the fact that there aren't any, as in this case).
Which is also why I wasn't surprised that it didn't work. The last time 
I heard anyone running any X server on a VAX, it was with DECs X server, 
which knew about the specific graphic controllers that exist there.

So I would suspect that the Xserver tries to poke at the spx driver, but 
also tries to poke directly at stuff, and this will just smash the 
system. But I'm halfway just guessing here...

> That aside....
>
>    
> > I wouldn't think the Xorg Xserver would work on a VAX, so I'm not
> > surprised.
> >      
> Perhaps not out of the box, but, unless they've broken something or the
> framebuffer is unusually funky, it would be fairly easy to make it
> work.  While I've worked with MIT X, not x.org (and definitely not the
> crawling design horror that is XFree86), I have done, for it, three
> custom ddx layers - enough to know that getting a simple one working is
> not really that complicated.  (What were the three?  NeXT 2bpp
> greyscale, Sun S24, and Sun cg14.)  Given hardware, leisure, and
> motivation, I could probably do it within a day or two of having the
> system set up and my tools installed, so I'd estimate a week or two for
> someone decent but starting from scratch.  (Unless the framebuffer
> doesn't have a dumb-array-of-pixels mode, in which case it'd take me
> longer.)
>    

Oh, no doubt you *could* make it work. My thought was only that noone have.

    Johnny