Subject: Re: Control fb problem on 8500

From: Michel Dänzer <[email-masked]>
Date: Sat, 19 Aug 2000 15:20:10 +0200

Michel Lanners wrote:

> On  18 Aug, this message from Daniel Jacobowitz echoed through cyberspace:
> >> In fact, before, the line length was exactly hpixels * bytes/pixel,
> >> whereas now there's an additional 0x20 bytes in each line. I have not
> >> been able to boot a 2.4.0 kernel with any fix applied, but you could try
> >> and build a version without those 0x20 bytes added (they are found in a
> >> few spots inside controlfb.c).
> >>
> >> As to why these 0x20 bytes were added, anybody know an explanation? And,
> >> if they do serve a purpose (I suppose so ;-), it would be better to add
> >> the exact number of bytes as a #define somewhere...
> >
> > *sigh*
> >
> > I have no idea where this came from, but 0x20 means it has something to
> > do with cursor support, I'd bet.  I seem to recall someone talking
> > about that a few months ago... that is how hardware cursor is generally
> > implemented, by a 32 pixel block at the end of the scanline.
>
> That's what I was thinking about. However, I'm not sure that XFree
> supports a display with discontiguous lines in video memory. I think I
> read that somewhere in some mailing list or X doc... Can any of the
> XFree specialists confirm?

It does support that, if not directly then certainly via shadowfb. Maybe the
shadowfb RefreshArea function would have to be modified to take account of
this.

> My XFree 4.0 goes into an infinite loop eating CPU time when I boot a
> 2.4.0 kernel.

Works fine here. I don't use the RPM stuff, stock 4.0.1/DRI .

The other Michel,
who once thought he was the glint maintainer

--
Earthling Michel Dänzer (MrCooper)  \  CS student and free software enthusiast
Debian GNU/Linux (powerpc,i386) user \   member of XFree86 and The DRI Project

** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/