Re: [PATCH V8 1/2] printk: remove tabular output for NULL pointer

[Joe Perches <joe@perches.com>]

On Thu, 2017-10-26 at 17:27 +1100, Tobin C. Harding wrote:
> Hi Joe,
> 
> thanks for your review.
> 
> On Wed, Oct 25, 2017 at 09:57:23PM -0700, Joe Perches wrote:
> > On Thu, 2017-10-26 at 13:53 +1100, Tobin C. Harding wrote:
> > > Currently pointer() checks for a NULL pointer argument and then if so
> > > attempts to print "(null)" with _some_ standard width. This width cannot
> > > correctly be ascertained here because many of the printk specifiers
> > > print pointers of varying widths.
> > 
> > I believe this is not a good change.
> > Only pointers without a <foo> extension call pointer()
>
> Sorry, I don't understand what you mean here. All the %p<foo> specifier code is
> handled by pointer()?

Sorry, I was imprecise/wrong.

None of the %p<foo> extensions except %pK and %p<invalid_foo>
actually use this bit of the pointer() call.

All of the other valid %p<foo> extension uses do not end up
at this block being executed so it's effectively only regular
pointers being output by number()

> > > Remove the attempt to print NULL pointers with a correct width.
> > 
> > the correct width for a %p is the default width.
> 
> It is the default width if we are printing addresses. Once we hash 64
> bit address to a 32 bit identifier then we don't have a default width.

Perhaps that 32 bit identifier should use leading 0's for
the default width.

aside:

Why hash 64 bits to 32?
Why shouldn't the hash width be 64 bits on 64 bit systems?