Path: utzoo!attcan!uunet!ncrlnk!ncr-sd!hp-sdd!hplabs!ucbvax!bloom-beacon!CS.CMU.EDU!rpd
From: rpd@CS.CMU.EDU (Richard Draves)
Newsgroups: comp.windows.x
Subject: X11R3 on RTs
Message-ID: <4Xak1Oy00hYPBnqUkv@cs.cmu.edu>
Date: 5 Dec 88 21:32:10 GMT
Sender: daemon@bloom-beacon.MIT.EDU
Organization: The Internet
Lines: 20

After much time with adb, I managed to get an R3 server working on a Megapel
display.  (Why doesn't IBM supply source for the ppc functions???)  I am
building my server with hc1.4u -g.  The server core-dumped, typically in some mi
function, when trying to tile the root window with the initial background.  The
function mpelTile calls ppcTileRect, which called through a null pointer.  Turns
out mpelInitScreen wasn't initializing one of the fields in its device-private
structure.  Adding a line like
        devPriv->replicateArea = ppcReplicateArea;
fixed the problem.

With that fixed, I saw occasional divide-by-zero faults in mfbPadPixmap.  It
seems the mysterious ppcPolyGlyphBlt is calling miPolyGlyphBlt with some 0x0
glyphs.  That is, gWidth and gHeight are 0 when it calls miPutImage.  This
eventually leads to mfbPadPixmap and mfbUnnaturalStippleFS trying to divide by
zero, because the width of a pixmap is zero.

Is this a bug in miPolyGlyphBlt or ppcPolyGlyphBlt?  Right now, I've modified
miPolyGlyphBlt to skip over glyphs whose height or width is zero.

Rich