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Date: Wed, 21 Feb 1996 22:30:57 +0900
From: Masahiro SEKIGUCHI <seki@sysrap.cs.fujitsu.co.jp>
Message-Id: <199602211330.WAA00818@sphinx.sysrap.cs.fujitsu.co.jp>
To: koshy@india.hp.com (A JOSEPH KOSHY)
Cc: hackers@FreeBSD.org
Subject: ISA device irq/mem auto-configuration
Newsgroups: rtd.freebsd.hackers
In-Reply-To: <199602210718.AA255777134@fakir.india.hp.com>
References: <199602210718.AA255777134@fakir.india.hp.com>
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 > This is a basic question about how we handle boards whose IRQ, I/O and
 > memory ranges can be autodetected at boot time.  

For IRQ, DMA channel, and/or memory addresses, I support the idea that
the driver should use the value detected at boot, *if* the driver can
DETECT them but can NOT set them.

If those settings can be changed by the driver, it *may* be better to
use values specified in the config.  I cannot just say one scenario is
better, in this case.

 > I have seen in some places "-1" being used as a kind of "wildcard" address
 > in some drivers.  Is this a convention?

I believe so.  I wrote my fe driver that way.  Indeed, config accepts
"?" for mem, for example, and generates -1.

 > Can anyone point me to further reading?

I expect that "http://freefall.cdrom.com/~erich/ddwg/ddwg.html" will
say something on the issue, in near future...

BTW, PC card support for FreeBSD includes some *smart* handling of
those settings.  Windows 95, or some other competing operating systems
have similar services for both PC cards and PnP ISA cards.  Is anyone
working on smart resource arbitration on FreeBSD for PnP ISA cards?