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Re: Should Linux VDSO be using symbol version based on the released kernel?

On 04/05/2016 13:37, Carlos O'Donell wrote:
> The Linux VDSO uses a singular version string, different by
> architecture, for all VDSO symbols e.g. LINUX_2.6.29 for s390x.
> Should the Linux kernel be using LINUX_4.5 as the version string
> for new VDSO symbols added in LINUX_4.5?
> That way we can talk sensibly about what VDSO symbols were added
> upstream, and talk sensible about the ABI/API being exported by
> any given kernel via the VDSO?
> Right now the version is really only meaningless version for
> future compat support.

Ideally I would say yes, however the way we use the vDSO is not
by exporting it directly in GLIBC own supported versions, but 
rather through wrappers and these already take care of check if
the symbol exist based on exported kernel version.

And I do not think we should think the vDSO as an stable ABI
that we must enforce symbol version compatibility, but rather
helper functions that GLIBC would use internally.

It is the same rationale based on other Linux exported facilities
that we do support directly.

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