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SubjectRe: [PATCHv7 01/33] ns: Introduce Time Namespace
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On 10/17/19 10:20 AM, Thomas Gleixner wrote:

[...]

> The architectures which implement VDSO are:
>
> arm, arm64, mips, nds32, powerpc, riscv, s390, sparc, x86, um
>
> arm64, mips, x86 use the generic VDSO. Patches for arm are floating
> around. UM is special as it just traps into the syscalls. No idea about the
> rest. Vincenzo might know.
>

There a couple of cases: hexagon and csky that have vDSOs for signal trampolines
if I recall correctly, but they do not fall into the category we are exploring
at the moment.

> The bad news is that we have no information (except on arm which has a
> config switch for VDSO) whether an architecture provides VDSO support or
> not.
>
> So unless you add something like
>
> config HAS_VDSO
> bool
>
> which is selected by all architectures which provide VDSO support, the only
> sane solution is to depend on GENERIC_VDSO_TIME_NS.
>
> TBH, I would not even bother. The architectures which matter and are going
> to use time namespaces already support VDSO and they need to move to the
> generic implementation anyway as we discussed and agreed on in Vancouver.
>
> Providing time name spaces for the non VDSO archs is a purely academic
> exercise.

I totally agree with this.

--
Regards,
Vincenzo

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