The subject line says it all.

I've compiled a XFree86 3.11 X server on my 1.0A system, intending to fix
a couple of bugs I've seen when running NetBSD on my i486 100Mhz portable.

The trouble is the freshly compiled X server bus errors when tring to do
outb instructions to the video controller. The XFree86 bsd i/o permisson
code says something about bsd systems allowing access to i/o instructions 
if the user program has opened the console or something.

Does any one have any ideas what the problem might be ?

Yes, the server is running setuid root. The super vga X server that came
precompiled with the XFree86 binary distribution works fine but can
only access 512K of my machine's 1Mb video RAM.

The XFree86 super vga server compiled ok, but I did have to disable support
for virtual consoles due to a missing header file; could this be the
problem ?

Where in the kernel are i/o instruction permissions handled ?

Thanks for any help people can give,

Gary.