Am 13.07.2014 21:22, schrieb Greg Kroah-Hartman: > On Sun, Jul 13, 2014 at 04:25:06PM +0200, Lars-Peter Clausen wrote: >> On 07/13/2014 04:03 PM, Richard Weinberger wrote: >>> Am 13.07.2014 15:56, schrieb Lars-Peter Clausen: >>>> On 07/13/2014 03:40 PM, Richard Weinberger wrote: >>>>> Am 13.07.2014 15:26, schrieb Lars-Peter Clausen: >>>>>> On 07/13/2014 11:45 AM, Richard Weinberger wrote: >>>>>>> Am 13.07.2014 11:27, schrieb Lennox Wu: >>>>>>>> As I said before, some configurations don't make sense. >>>>>>> >>>>>>> If such a configuration can be achieved using allmod/yesconfig it has to be fixed. >>>>>>> Chen's fixes seem reasonable as not all architectures support iomem. >>>>>> >>>>>> Maybe we should stub out ioremap() and friends when COMPILE_TEST is enabled to avoid these linker errors. That's in my opinion better than turning most of the 'depends on >>>>>> COMPILE_TEST' into 'depends on COMPILE_TEST && HAS_IOMEM'. The issue comes up quite a lot and it is often overlooked when adding a driver that can be build when COMPILE_TEST is >>>>>> enabled. >>>>> >>>>> And what should this stub do? >>>>> Except calling BUG()... >>>> >>>> return NULL; >>>> >>>> It's for compile testing, it's not meant to work at runtime. >>> >>> Hm, I really don't like the idea of having a non-working kernel. >>> IMHO either it should build _and_ run and nothing else. >>> Greg, what do you think? >> >> The kernel will still be working fine and you can run it on a system. The >> drivers which use ioremap() or similar are probably not instantiated on a >> system that does not provide HAS_IOMEM. But even if it was the driver should >> handle ioremap() returning NULL gracefully and abort the driver probe. That >> said you'll probably not run a kernel that was built with COMPILE_TEST on >> your real hardware since it contains so many drivers that are completely >> useless on your hardware. The idea of COMPILE_TEST is to have as much >> compile test exposure as possible to the code that is enabled by >> COMPILE_TEST. Stubbing out ioremap() and friends when HAS_IOMEM is not set >> and COMPILE_TEST is set makes it easier to get there. > > I run my kernels with COMPILE_TEST enabled as I need to build test > things that I don't happen to use. > > I like the 'return NULL' option for this, it hits us all the time, might > as well fix it properly like this so that we don't have to deal with > Kconfig changes everywhere. > > Also put a big "This platform does not support IOMEM" error printk in > there, so that people have a chance to figure out what is going on if > they happen to run such a driver on a platform that can't support it. Maybe we could add COMPILE_TEST to the version string too? Just to detect such kernels fast in user bug reports... Thanks, //richard -- To unsubscribe from this list: send the line "unsubscribe linux-iio" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
