Date: Mon, 24 Feb 2003 14:22:05 -0800 From: Marcel Moolenaar <marcel@xcllnt.net> To: "M. Warner Losh" <imp@bsdimp.com> Cc: freebsd-arch@FreeBSD.ORG Subject: Re: [RFC] splitting of conf/NOTES Message-ID: <20030224222205.GA1032@athlon.pn.xcllnt.net> In-Reply-To: <20030224.143957.17279856.imp@bsdimp.com> References: <20030224094856.GA21088@athlon.pn.xcllnt.net> <20030224.060315.63039059.imp@bsdimp.com> <20030224204113.GC661@athlon.pn.xcllnt.net> <20030224.143957.17279856.imp@bsdimp.com>
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On Mon, Feb 24, 2003 at 02:39:57PM -0700, M. Warner Losh wrote:
> In message: <20030224204113.GC661@athlon.pn.xcllnt.net>
> Marcel Moolenaar <marcel@xcllnt.net> writes:
> : The tricky part still is that there's a lot of assumptions about
> : the BIOS and the BIOS data area that, if I understand correctly,
> : goes beyond plain ISA and is best described as PC specific. I think
> : this is more a driver issue than anything else.
>
> Well, I'm not sure I understand what you are getting at here, so I'll
> take a stab at guessing (dangerous I know):
>
> There's a PC standard for ROMs that live in the ISA hole.
What I'm getting at is: will this only be i386 ROMs (ie with
i386 code) or is it possible that when a machine has ISA
emulation, one should be able to scan for ROMs in the ISA hole
and find something that can actually be used. I'm inclined to
assume that ROMs found in the ISA hole are i386 specific and
ISA emulation is limited to I/O ports and registers only.
Thus: even if ISA (sec) is not i386 specific, there may be ISA
drivers that depend on ROM, BIOS and/or BIOS data (see sys/fb/vga.c)
and consequently are not pure ISA drivers. They are PC drivers.
This is the driver part I was referring to in my previous mail.
On the ia64 branch I fiddled with sys/conf/files.* to make PC/ISA
device drivers actually depend on the existence of "device isa",
so that I could create an ISA-less kernel (needed for pluto{1|2}).
This triggered some interesting bugs, such as the fact that the
high-level syscons code (ie sc(4) itself) has been attached to
the ISA bus and is identified/probed as an ISA device. I had to
break the artificial dependency to get syscons working (with the
supprt of a PCI VGA wannabe driver).
--
Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net
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