Re: [RFC][PATCH] printk: Add %pb to print bitmaps

Peter Zijlstra
2012-05-09T20:58:57Z

On Wed, 2012-05-09 at 12:07 -0700, Andrew Morton wrote:
> On Wed, 09 May 2012 15:27:23 +0200
> Peter Zijlstra <peterz@infradead.org> wrote:
>
> > + * - 'b' For a bitmap, consumes 2 args, second is int
>
> There's a pretty widespread convention that %b is used to print in
> binary: printf("%b", 10) -> 1010. Regrettably it isn't part of
> standard C, but it's often supported anyway. Perl's printf does this
> as well. Perl uses %B also.
>
> If we later want to add binary printing to kernel print(), we'd presumably
> use %pb, to match this precedent.

I'd expect something like %ub, %p would take a pointer to a value.

Too bad both %b and %B generate a warning, it would be rather trivial to
add base 2 number stuff.

> So perhaps it would be better to avoid consuming `b' for bitmaps?

With %.*pb not actually working I could use %pC to mean a cpumask and
skip the generic bitmap stuff.