Date: Wed, 06 May 1998 00:44:49 -0700 From: Mike Smith <mike@smith.net.au> To: Don Lewis <Don.Lewis@tsc.tdk.com> Cc: Mike Smith <mike@smith.net.au>, Archie Cobbs <archie@whistle.com>, stefan@promo.de (Stefan Bethke), luigi@labinfo.iet.unipi.it, freebsd-hackers@FreeBSD.ORG Subject: Re: ISA-PnP w\o BIOS support? Message-ID: <199805060744.AAA01906@antipodes.cdrom.com> In-Reply-To: Your message of "Wed, 06 May 1998 01:20:04 PDT." <199805060820.BAA20482@salsa.gv.tsc.tdk.com>
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> On May 5, 11:26pm, Mike Smith wrote: > } Subject: Re: ISA-PnP w\o BIOS support? > > } This actually falls a little short. It's easier to look at it from a > } different angle, too. > } > } For each PnP device/function in the system > } If the device/function is not supported (unknown, no driver present) > } deconfigure device (if required) > } continue > } else > } while resources required > } allocate new resources > } test resources (using PnP test facility if available) > } endwhile > } if resources available > } allocate a new driver instance, assign resources > } else > } continue > } endif > } endfor > } > } For each explicitly-configured ISA devices > } if resource config does not conflict with PnP-configured device > } allocate resources > } if probe succeeds > } allocate new driver instance > } else > } free resources > } endif > } endif > } endfor > > Why would you not want to reverse the order and configure the explicitly > configured ISA devices first and the PnP devices last? Because your brute-force probe may find a device that is actually a PnP device, and which has been allocated resources by the BIOS. > If you configure > the PnP devices first, they might use resources required by the ISA > devices. In most cases, this is not possible. You can detect I/O and memory conflicts using the probe techniques, and IRQ conflicts are impossible on systems that support BIOS configuration of resources. > If you configure the ISA devices first, then you should be > able to adjust the resources used by the PnP devices so they don't > conflict with the ISA devices. Given that resource conflicts are pretty unlikely, this isn't a real problem. The actual relative ordering is not terribly important - on the plus side doing the ISA probe first lets you "wire down" specific devices to IO combinations, but it loses insofar as you may get a less than optimal driver/device match just because the device matched an ISA probe instead. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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