Date: Wed, 10 Jan 1996 23:41:12 +0200 (SAT) From: Robert Nordier <rnordier@iafrica.com> To: msmith@atrad.adelaide.edu.au (Michael Smith) Cc: hackers@freebsd.org Subject: Re: DOS File system fixes Message-ID: <199601102141.XAA00185@eac.iafrica.com> In-Reply-To: <199601100616.QAA08290@genesis.atrad.adelaide.edu.au> from "Michael Smith" at Jan 10, 96 04:46:28 pm
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According to Michael Smith: > Robert Nordier stands accused of saying: > > > > Maintaining the BIOS environment is a way that is acceptable to both FBSD > > and the BIOS might also get tricky. There are parts of the BIOS you > > probably just don't want to get called: like 0x15/0x87 which is only a > > helper routine but attempts a return to protected mode with interrupts > > disabled. > > Would other parts of the BIOS attempt to call this? If a BIOS function > was called, so far as it could tell, from an address in low memory in > real mode? I was really thinking of the problem of running unsupported hardware through supplied device drivers when I wrote this. (0x15/0x87 is a memory transfer function.) I had just been looking at a CD-ROM driver that made this sort of real/protected mode assumption. With BIOS itself, 0x15/0x87 shouldn't be something to worry about, so not a good example, really. Looking at it now, though, there is something that needs considering. I'm assuming the typical situation of, "It works under dos/win, so why can't I use it under FreeBSD?" The reason it works under dos may be an OEM device driver which fixes bugs in the firmware/adds features to the firmware (eg. SCSI controller cards which are not VDS compliant running under mswin). If all that is holding things together is the device driver (being that it is cheaper to revise than the firmware), leaving out the driver and just going after the *ROM stuff isn't going to be "totally successful." So we may need to look at the dos device driver layer for the device support package. -- Robert Nordier rnordier@iafrica.com E.A.C.
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