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

From: Vincenzo Frascino
Date: Wed Oct 16 2019 - 06:42:49 EST



On 10/16/19 11:39 AM, Thomas Gleixner wrote:
> On Wed, 16 Oct 2019, Vincenzo Frascino wrote:
>
> < Trim 250+ lines ( 3+ pages) of pointlessly wasted electrons >
>
>>> --- 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.
>

Agreed, this is even better.

> < Trim another gazillion of useless lines >
>
> See: https://people.kernel.org/tglx/notes-about-netiquette
>
> Thanks,
>
> tglx
>

--
Regards,
Vincenzo