On Mon, 11 Oct 2021 at 12:57, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > On Mon, Oct 11, 2021 at 11:10 AM Dmitry Baryshkov > <dmitry.baryshkov@xxxxxxxxxx> wrote: > > > > On Mon, 11 Oct 2021 at 09:09, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > > > On Mon, Oct 11, 2021 at 6:11 AM Dmitry Baryshkov > > > <dmitry.baryshkov@xxxxxxxxxx> wrote: > > > > On Sun, 10 Oct 2021 at 20:42, Arnd Bergmann <arnd@xxxxxxxx> wrote: > > > > > > > > The patch seems correct, but it becomes overcomplicated. What about: > > > > - restoring QCOM_SCM stubs > > > > > > The stubs are what has led to the previous bugs in this area to often > > > go unnoticed for too long, as illustrated by your suggestion > > > > > > > - making ARM_SMMU select QCOM_SCM if ARM_SMMU_QCOM > > > > > > I assume you meant "select QCOM_SCM if ARCH_QCOM", > > > after we stop using ARM_SMMU_QCOM? > > > > > > > This would have almost the same result as with your patch, but without > > > > extra ARM_SMMU_QCOM Kconfig symbol. > > > > > > The "almost" is the problem: consider the case of > > > > > > CONFIG_ARM=y > > > CONFIG_COMPILE_TEST=y > > > CONFIG_ARCH_QCOM=n > > > CONFIG_ARM_SMMU=y > > > CONFIG_DRM_MSM=m > > > CONFIG_QCOM_SCM=m (selected by DRM_MSM) > > > > > > The stubs here lead to ARM_SMMU linking against the QCOM_SCM > > > driver from built-in code, which fails because QCOM_SCM itself > > > is a loadable module. > > > > I see. The idealist in me wishes to change my suggestion to > > 'select QCOM_SCM if ARCH_QCOM || COMPILE_TEST' > > but I have the subtle feeling that this also might fail somehow. > > I think that would actually work, but it has the nasty side-effect > that simply flipping 'CONFIG_COMPILE_TEST' changes what > the kernel does, rather than just hiding or unhiding additional > options. > > > > We can move the "select QCOM_SCM" in the ARM_SMMU_QCOM > > > symbol if we make that a tristate though, if you want to separate it > > > a little more. > > > > This would complicate things a bit, as we would no longer be able to > > use 'arm-smmu-$(CONFIG_ARM_SMMU_QCOM) +=' construct. > > I'm fairly sure we could still use that, Kbuild is smart enough > to include both 'file-m +=' and 'file-y += ' in 'file.ko', see > scripts/Makefile.lib: > > # If $(foo-objs), $(foo-y), $(foo-m), or $(foo-) exists, foo.o is a > composite object > multi-obj-y := $(call multi-search, $(obj-y), .o, -objs -y) > multi-obj-m := $(call multi-search, $(obj-m), .o, -objs -y -m) > multi-obj-ym := $(multi-obj-y) $(multi-obj-m) > > # Replace multi-part objects by their individual parts, > # including built-in.a from subdirectories > real-obj-y := $(call real-search, $(obj-y), .o, -objs -y) > real-obj-m := $(call real-search, $(obj-m), .o, -objs -y -m) Ah, I thought Kbuild would accept only foo-y, please excuse me. > > What doesn't work is having a built-in driver in a directory that is > guarded with a =m symbol, or including a =m object into a =y > module. > > Arnd -- With best wishes Dmitry
