> On sparc64, for example, after I pointed this out to DaveM, he was able > to implement the new iomap interface without the 'if (pio-mem-area)' > branch present on x86.
Yup, we did that from day 1 on powerpc :-) However, I don't totally agree with adding some other remapping layer here, I think if we want PIO 0 to be illegal, then make it illegal at the HW level too. The reason is in fact the same as Linus invoked for remapping it in the first place -> make things look like an x86 :-) That is, quite a few non-x86 machines do have some kind of superIO chip or other set of legacy devices around. They also commonly have VGA cards hard decoding VGA PIO addresses. So here's a very simplified version on how most non-x86 platforms do PIO : at boot: pci_io_base = ioremap(MAGIC_PIO_REGION); and then #define inb(port) (readb(pci_io_base + (port))) The nice thing with that approach is that all those legacy x86 drivers for bits in your SuperIO chip or for VGA do actually still work when they do inb(STUPID_HARD_CODED_IO_PORT); While if we now add some magic remapping to make 0 illegal, that will break and all those legacy drivers would have to be fixed, which nobody wants to do. So I do stand firm there. I don't necessarily mind deciding that 0 is an illegal PIO address, but if we're going to do that, we should make it illegal as a HW PIO address, not by adding a remapping trick to something that really doesn't want more than it already has :-) Ben. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
