Re: [PATCHv7 01/33] ns: Introduce Time Namespace

On Wed, 16 Oct 2019, Vincenzo Frascino wrote:

< Trim 250+ lines ( 3+ pages) of pointlessly wasted electrons >

quoted

--- a/init/Kconfig
+++ b/init/Kconfig

@@ -1096,6 +1096,13 @@ config UTS_NS
 	  In this namespace tasks see different info provided with the
 	  uname() system call
 
+config TIME_NS
+	bool "TIME namespace"
+	default y

Having CONFIG_TIME_NS "default y" makes so that the option is selected even on
the architectures that have no support for time namespaces.
The direct consequence is that the fallbacks defined in this patch are never
selected and this ends up in kernel compilation errors due to missing symbols.

The error below shows what happens on arm64 (similar behavior on other
architectures):

aarch64-linux-gnu-ld: kernel/time/namespace.o: in function `timens_on_fork':
kernel/time/namespace.c:321: undefined reference to `vdso_join_timens'

My proposal is to keep TIME_NS "default n" (just remove "default y"), let the
architectures that enable time namespaces select it and make CONFIG_TIME_NS
select GENERIC_VDSO_TIME_NS if arch has HAVE_GENERIC_VDSO.

Nah.

config TIME_NS
	bool "TIME namespace"
	depends on GENERIC_VDSO_TIME_NS
	default y

and in lib/vdso/Kconfig

config GENERIC_VDSO_TIME_NS
	bool

and let architectures which have support for the VDSO bits select it.

< Trim another gazillion of useless lines >

See: https://people.kernel.org/tglx/notes-about-netiquette

Thanks,

	tglx