Re: so_rerror

[Havard Eidnes <he%NetBSD.org@localhost>]

> On 06/11/2018 00:31, Christos Zoulas wrote:
>> I agree as I wrote above, the issue is to do it in a non-intrusive way
>> or make sure that nothing breaks...
>
> I'm not sure how much more non intrusive it can be - everything
> I've done is standards compliant, documented by POSIX and
> implemented previously in at least one other OS.

But that does not preserve backward compatibility.

It has for ~forever been possible to run a new kernel with an
older user-land.  With the introduction of this error in 8.0,
that is no longer possible -- e.g. a BIND from before the fix was
applied (which didn't make the 8.0 cut, so was applied later on
the netbsd-8 branch...), would "seemingly randomly" stop
responding to UDP queries, and you are forced to upgrade your
user-land to 8.0 (or even newer along netbsd-8, in order to pick
up the BIND fix).

Therefore, reporting of the "new" error code should be an opt-in
thing, not something which is default on for the entire OS and
therefore all applications.

Regards,

- Håvard