Date: Sat, 30 May 1998 08:16:02 +0100 (BST) From: Doug Rabson <dfr@nlsystems.com> To: "Justin T. Gibbs" <gibbs@narnia.plutotech.com> Cc: current@FreeBSD.ORG Subject: Re: FreeBSD/alpha status report (2) Message-ID: <Pine.BSF.3.95q.980530080644.15699Y-100000@herring.nlsystems.com> In-Reply-To: <199805300519.XAA02620@narnia.plutotech.com>
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On Fri, 29 May 1998, Justin T. Gibbs wrote: > > Along the way, I have successfully probed for simulated devices on a > > simulated PCI bus and attached simulated SCSI disks :-). I am *not* > > currently using NetBSD's bus_space stuff to handle accesses to device i/o > > ports and memory. Given that 99% of the machines that the port will work > > on don't need the complexity of bus_space, I have taken the Linux route > > and each chipset will supply versions of inb etc which perform the > > relavent contortions. > > I suppose I don't understand the rational here. The i386 port > doesn't have to go through any contortions in it's bus space > implemenation and implementing bus space for FreeBSD x86 (look in > i386/include/bus.h) was *trivial*. So why not use bus space? The > CAM drivers already use it, you say that 99% of Alphas can use a > "simple" implementation, and it buys us the ability to more easily > port code from NetBSD? Just because you seem to believe that NetBSD's > implementation of the bus space and bus DMA interfaces for Alpha are > overly complex, doesn't mean that the interfaces themselves are a > bad idea. I am not saying that there won't be a <machine/bus.h>. I am saying that I don't think that all the chipset implementations need to implement it. If I do a bus_space interface, I expect that it will be something like i386/include/bus.h. It is possible that TurboChannel and TurboLaser boxes with multiple PCI busses might provide their own implementation rather than the generic one. -- Doug Rabson Mail: dfr@nlsystems.com Nonlinear Systems Ltd. Phone: +44 181 951 1891 Fax: +44 181 381 1039 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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