Messages in this thread | | | Date | Mon, 21 Nov 2005 11:27:05 -0800 (PST) | From | Linus Torvalds <> | Subject | Re: [PATCH 4/5] Centralise NO_IRQ definition |
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On Mon, 21 Nov 2005, Matthew Wilcox wrote: > > On Mon, Nov 21, 2005 at 10:55:24AM -0800, Linus Torvalds wrote: > > Quite frankly, if we change [PCI_]NO_IRQ to -1, there's almost certainly > > going to be a lot of drivers breaking. > > There's only one driver using NO_IRQ today (outside of architectures > which define NO_IRQ to -1, that is). So *this* series of patches should > break nothing.
Right. But the point is that most drivers will do something like
if (!dev->irq) return;
(whatever, made up). And that having NO_IRQ be anything but 0 is thus fundamentally broken.
Because the fact is, NO_IRQ _is_ zero. And exactly because it's zero, and that is encoded everywhere, nobody uses it.
> That's a common misreading of the PCI spec -- it actually says the > opposite.
I'm NOT talking about PCI specs.
I'm talking about real hardware.
Read pretty much _any_ data-sheet for an interrupt router, and you'll see that the bit pattern 0000 means _disabled_.
In other words, I'm talking about HARD REALITY.
I know, it's a bitch.
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