From: chrisl@county.lmt.mn.org (Chris Laurel) Subject: I/O protection level Date: 26 Aug 1992 18:32:27 GMT
I want play around with the enhanced features of my Fahrenheit 1280
video board (S3-based), but in order to do this I need to be able to access
portsabove 0x3ff. Ports above 0x3ff are not mapped by Linux into the per-
process IO bitmap, so I cannot use the ioperm system call. I looked through
the Linux source code and saw code for an 'iopl' system call, but I was
unable to get this to work (Linux 0.97)--the call was not present in the C
libraries. Could someone tell me how to use the iopl system call? Or
inform me of another method to access high ports? I presume that writing an
assembly language routine to set the iopl directly by pushing/popping the
flags register will not work if it is executed by a user process . . .
Also, does anyone have any S3 hacks for linux that they would be willing to
share?
Thanks,
Chris Laurel
CHRISL@county.lmt.mn.org