Subject: Re: Unable to mmap /dev/mem
To: Jared D. McNeill <>
From: Matthieu Herrb <>
List: tech-x11
Date: 11/13/2000 16:57:40
You wrote (in your message from Monday 13)
 > On Mon, 13 Nov 2000, Matthieu Herrb wrote:
 > > You should try to use ktrace on the applications in question, if you
 > > haven't already done it.
 > Here are the last 40 lines of the ktrace when run as root. Hope this is
 > helpful...
 >   4054 snes9x   CALL  mmap(0,0x800000,0x1,0x1,0,0,0xcd000000,0xffffffff)
 >   4054 snes9x   RET   mmap -1 errno 22 Invalid argument

Yes. It's trying to mmap the framebuffer, which has a physical address
that is above the top of the RAM. /dev/mem doesn't allow this.

In this case you need to use the aperture driver and to patch the
application to try /dev/xf86 if /dev/mem fails. 

The aperture driver will allow mmaping of any address above the end of
physical memory or in the BIOS VGA range.