Messages in this thread | | | Date | Thu, 15 Jul 1999 22:13:37 -0700 | From | David Hinds <> | Subject | Re: New kernel/resource.c |
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On Thu, Jul 15, 1999 at 03:42:52PM -0700, Linus Torvalds wrote: > > On Thu, 15 Jul 1999, David Hinds wrote: > > > > The names "pci_io_resource" and "pci_mem_resource" should really be > > changed to be non-bus-specific, because they are not just PCI > > resources. > > Wrong. They are. > > If somebody has a system with both sbus and PCI, he'd better create the > sbus version of the resources. > > That wasn't how it used to be, but that is how it is now.
Hmmm, I'm afraid you've lost me here. Resources on different busses go in different resource trees? It seems to me that host processor address space is the most fundamental resource to be arbitrated. How do we do that, if each bus is kept track of separately?
> No. There is one kind of resource - the one from the perspective of a > driver. Anything else is irrelevant.
Well, I guess it's hard for me to argue if you believe the perspective that matters to me is irrelevant.
> The Linux way of accessing PCI is though inb/outb() and readb/writeb() > interfaces. The "pci_io_resource" and "pci_mem_resource" protect those > interfaces, and nothing else.
You've lost me again. inb/outb and readb/writeb are not PCI specific, so how can they be arbitrated using a PCI-specific resource tree?
> If you have code that reliably fully enumerates the hardware, then we'll > look at that code and start changing drivers. Backwards compatibility is > evil if it results in things that do not make sense.
I doubt that the code to enumerate hardware will ever be reliably complete, due to the nature of PC hardware. It will only ever be a 90% (or 95%, or 99%) solution to the problem. I think we can only hope it to be usually good enough.
Gratuitous disregard for backwards compatibility is also evil. You should be able to point to real costs (time, space, complexity), not just assert that something doesn't meet your impression of semantic cleanliness. In this particular case, I think my solution wins on the objective measures. I think I'm a fairly sensible person and it makes sense to me, independent of the compatibility issues. You can place whatever value you wish on that judgement; I'd guess not much.
-- Dave Hinds
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