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From: veit@fanoe.gmd.de (Holger Veit)
Subject: Re: 3C501 Ether driver, XS3+codrv
Message-ID: <1993Mar12.074612.22684@gmd.de>
Sender: veit@fanoe (Holger Veit)
Nntp-Posting-Host: fanoe
Organization: GMD - German National Research Center for Computer Science
References: <1993Mar9.043947.4016@netcom.com> <1993Mar10.213242.423@netcom.com> <1993Mar11.090535.9238@gmd.de> <1993Mar12.033550.2947@netcom.com>
Date: Fri, 12 Mar 1993 07:46:12 GMT
Lines: 36
In article <1993Mar12.033550.2947@netcom.com>, hasty@netcom.com (Amancio Hasty Jr) writes:
|> In article <1993Mar11.090535.9238@gmd.de> veit@fanoe.gmd.de (Holger Veit) writes:
|> >In article <1993Mar10.213242.423@netcom.com>, thinman@netcom.com (Technically Sweet) writes:
|> >kernel without problems. One is I/O and interrupt handling. There is
|> >a hack to give the xserver the privilege to access I/O but
|> >this imposes at least significant security leaks, if not stability
|> >problems. The way it is done in this context is not recommended in
|> >general.
|> Well, the original patches which I distributed for X386 included i/o
|> bitmap permissions. This approach was abandoned because of cards
|> based on the 8514/a, like s3 chipsets use i/o ports much higher
|> than normal vgas. We can still do it but it will be costly in
|> terms of memory allocation for the process header.
This is because the 8514s have quite a wierd I/O space mapping. The constant
part is in the low byte, the high byte selects registers. I know this
has been done by intent to avoid address clashes, but as you correctly
remark, this enlarges the i386 task segment for each process by quite a
sparsely filled I/O perm map.
Anything possible to improve this situation? Is it possible to
remap the I/O space 8514s to something more dense (besides a VGA emulation
mode)? I believe, software emulation of the I/O permission testing is
too time consuming.
Holger
|> e-mail hasty@netcom.com | sunvis.rtpnc.epa.gov:/pub/386bsd/incoming
--
Dr. Holger Veit | INTERNET: Holger.Veit@gmd.de
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