On Sun, 2017-06-25 at 21:53 +0200, Enrico Weigelt, metux IT consult
wrote:
> On 25.06.2017 19:27, Joe Perches wrote:
>
> > Every use of %M is going to cause gcc when using __printf to emit
> > a warning like:
> >
> > unknown conversion type character ‘M’ in format [-Wformat=]
>
> Yeah, that's still an open problem. Actually, I still haven't found out,
> how it's done w/ all the other kernel-internal conversions.
Everything else uses "%p<foo>", <object reference>
> I was under
> the impression, there was some magic to tell the compiler which letters
> correspond to which types - unfortunately, didn't find anything like
> that. Is that really hardcoded in gcc ?
>
> > Beyond that, why is this useful?
>
> Use that instead of %d where errno values are printed/logged.
> > There can't possibly be any fast-path use.
>
> I'm using it eg. for driver development - always having to look up the
> numbers is quite ugly and time consuming.
>
> > Why not just create a function that does errno/string conversions?
>
> Already was about to do so. Shall I call it strerror() ?
I presume kstrerror
So use something like
"%d: (%s)", errno, kstrerror(errno)
