04.06.2019 17:50, Thierry Reding пишет: > On Tue, Jun 04, 2019 at 05:41:53PM +0300, Dmitry Osipenko wrote: >> 04.06.2019 17:18, Thierry Reding пишет: >>> On Tue, Jun 04, 2019 at 04:10:31PM +0200, Thierry Reding wrote: >>>> On Tue, Jun 04, 2019 at 04:53:17PM +0300, Dmitry Osipenko wrote: >>>>> 04.06.2019 14:20, Thierry Reding пишет: >>>>>> On Thu, May 02, 2019 at 02:38:13AM +0300, Dmitry Osipenko wrote: >>>>>>> The driver's compilation doesn't have any specific dependencies, hence >>>>>>> the COMPILE_TEST option can be supported in Kconfig. >>>>>>> >>>>>>> Reviewed-by: Chanwoo Choi <[email protected]> >>>>>>> Signed-off-by: Dmitry Osipenko <[email protected]> >>>>>>> --- >>>>>>> drivers/devfreq/Kconfig | 2 +- >>>>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>>>> >>>>>>> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig >>>>>>> index 56db9dc05edb..a6bba6e1e7d9 100644 >>>>>>> --- a/drivers/devfreq/Kconfig >>>>>>> +++ b/drivers/devfreq/Kconfig >>>>>>> @@ -93,7 +93,7 @@ config ARM_EXYNOS_BUS_DEVFREQ >>>>>>> >>>>>>> config ARM_TEGRA_DEVFREQ >>>>>>> tristate "NVIDIA Tegra30/114/124/210 DEVFREQ Driver" >>>>>>> - depends on ARCH_TEGRA >>>>>>> + depends on ARCH_TEGRA || COMPILE_TEST >>>>>>> select PM_OPP >>>>>>> help >>>>>>> This adds the DEVFREQ driver for the Tegra family of SoCs. >>>>>> >>>>>> You need to be careful with these. You're using I/O register accessors, >>>>>> which are not supported on the UM architecture, for example. >>>>>> >>>>>> This may end up getting flagged during build testing. >>>>> >>>>> We have similar cases in other drivers and it doesn't cause any known >>>>> problems because (I think) build-bots are aware of this detail. Hence >>>> >>>> I don't understand how the build-bots would be aware of this detail. >>>> Unless you explicitly state what the dependencies are, how would the >>>> build-bots know? Perhaps there's some logic built-in somewhere that I >>>> don't know about? >>> >>> So looks like COMPILE_TEST has a !UML dependency, so this might just >>> work. >>> >>> Acked-by: Thierry Reding <[email protected]> >>> >> >> Thank you very much for the clarification! Certainly that would caused >> problems already since there are such cases all over the kernel, >> including Tegra drivers. > > In the cases that I'm aware of we used to explicitly list all the > dependencies that would've otherwise been pulled in by the ARCH_TEGRA > dependency to make sure there were no issues. > > Now that we've been discussing this I vaguely recall a discussion about > the only real issue nowadays being HAS_IOMEM and since that's only > missing on UML, that may have been the reason for why the !UML > dependency was added. > > Yes, looks like that was it: > > commit bc083a64b6c035135c0f80718f9e9192cc0867c6 > Author: Richard Weinberger <[email protected]> > Date: Tue Aug 2 14:03:27 2016 -0700 > > init/Kconfig: make COMPILE_TEST depend on !UML > > UML is a bit special since it does not have iomem nor dma. That > means a > lot of drivers will not build if they miss a dependency on > HAS_IOMEM. > s390 used to have the same issues but since it gained PCI support > UML is > the only stranger. > > We are tired of patching dozens of new drivers after every merge > window > just to un-break allmod/yesconfig UML builds. One could argue that > a > decent driver has to know on what it depends and therefore a missing > HAS_IOMEM dependency is a clear driver bug. But the dependency not > obvious and not everyone does UML builds with COMPILE_TEST enabled > when > developing a device driver. > > A possible solution to make these builds succeed on UML would be > providing stub functions for ioremap() and friends which fail upon > runtime. Another one is simply disabling COMPILE_TEST for UML. > Since > it is the least hassle and does not force use to fake iomem support > let's do the latter. > > Link: > http://lkml.kernel.org/r/[email protected] > Signed-off-by: Richard Weinberger <[email protected]> > Acked-by: Arnd Bergmann <[email protected]> > Cc: Al Viro <[email protected]> > Signed-off-by: Andrew Morton <[email protected]> > Signed-off-by: Linus Torvalds <[email protected]>
That was a wise solution. Thank you very much again for the detailed comment! Very appreciate that! > Oh wow... almost three years now. Please don't pay much attention to the time, it never stops. Live in the moment :)
