Date: Mon, 16 Aug 93 09:49:38 -0400
From: DJ Delorie <dj AT ctron DOT com>
To: eyal AT fir DOT canberra DOT edu DOT au
Cc: djgpp AT sun DOT soe DOT clarkson DOT edu
Subject: Re: SVGA page fault risk.


> If one moves data into video memory, the extender will trap page
> faults and swap the pages. This is a nice feature; However, if one
> writes using a word or long instruction and the page is crossed
> during the instruction then an infinit loop of page faults and page
> swap will happen. Every time that the instruction is restarted it
> will fault on either the first bytes or on the last bytes. It will
> never have both pages active.

This is correct.  That's also why there is a separate set of pages for
split read/write an a status bit in the driver that says if they're
there - movs hangs the same way, and if you can't do a split
read/write you have to use system ram as a temp buffer.