On Thu, May 03, 2007 at 10:36:14AM +0200, Martin Schwidefsky wrote: > On Wed, 2007-05-02 at 22:30 -0700, Greg KH wrote: > > > Hide the config menu for userspace I/O on s390. > > > > Why? Who says s390 can't have userspace I/O drivers someday? > > Theoretically yes, but in practice this is very unlikely to happen. Some > reasons why: > 1) There are only very few device drivers for s390, the few we need > we'll do as kernel space drivers > 2) The irq abstraction of uio is awkward. The irq handler uses a 32-bit > integer. On s390 each ccw device has it's own irq and ccw devices are > identified with a string "x.y.zzzz". Then there are devices that deliver > external interrupts where a 16-bit number is used to identify the > source. You could invent some mapping logic of a 32 bit integer to all > the possible interrupt sources but it doesn't really match. > 3) s390 doesn't use memory mapped i/o, you always need to execute a > privileged instruction to trigger activity on the device, e.g. ssch for > a ccw device, siga for qdio, nqap for crypto, ... > > So I have my doubts that we will ever see a uio driver for s390. If we > do we can unhide the config menu again.
Ok, that's find, can you bounce me the patch that made this change again? thanks, greg k-h - 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/
