On Tue, 19 Mar 2019 10:18:00 +0000
Petr Machata <pe...@mellanox.com> wrote:
> Stephen Hemminger <step...@networkplumber.org> writes:
>
> > On Mon, 18 Mar 2019 15:02:53 +0100
> > Andrew Lunn <and...@lunn.ch> wrote:
> >
> >> On Mon, Mar 18, 2019 at 01:15:41PM +0000, Petr Machata wrote:
> >> >
> >> > Andrew Lunn <and...@lunn.ch> writes:
> >> >
> >> > >> +enum rtnl_link_down_reason_major {
> >> > >> + RTNL_LDR_OTHER,
> >> > >
> >> > > Does 'other' make any sense? Seem better to just not report anything
> >> > > at all, or add a comment that more reasons should be added at the end
> >> > > to reflect whatever the hardware or software can determine.
> >> >
> >> > You still have the minor code to give you some information.
> >>
> >> The problem i have with OTHER, is that you know it is not NO_CABLE,
> >> UNSUPPORTED_CABLE, AUTONEG_FAILURE, etc. But for people to know what
> >> OTHER cannot be, they have to know all the codes.
> >>
> >> But then later, some other driver writer does the right thing, adds a
> >> new value to the end for a code they can detect. Say for example
> >> SFP_OVERHEATED. This happened to be what the previous driver was
> >> using for OTHER. Now we have one driver returning SFP_OVERHEATED and
> >> the older driver OTHER. So OTHER no longer actually mean 'other', it
> >> just means something random, which could actually be the same as one
> >> of the listed codes.
> >>
> >> You can stop this from happening by not having OTHER. Always add a new
> >> code if there is something you can report, but there currently is no
> >> code for it. And the userspace tool should just print the decimal
> >> value if it does not know what text to translate it into.
> >
> > Gut feel is that enumerated values are going to grow and grow and be
> > long term API headache.
> >
> > Would it be possible to use a string like the external ack error
> > message?
>
> It would, but then if any automated tools want to make use of it beyond
> just blindly displaying it, they will need to parse it with all the
> usual problems. In the end the string itself becomes the API anyway.
>
> Adding a string would make sense as an extra piece of information, not
> as the primary channel. Extack is like this as well, the primary channel
> there is errno.
The problem with codes is that without some standard (like IETF) the
values are very system specific and likely to get lots of of version churn.
