linux-kernel - Re: How do I printk <type> correctly?

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Message-Id: <20081029083403.5afac2c1.randy.dunlap@oracle.com>
Date:	Wed, 29 Oct 2008 08:34:03 -0700
From:	Randy Dunlap <randy.dunlap@...cle.com>
To:	dedekind@...radead.org
Cc:	Alexey Dobriyan <adobriyan@...il.com>,
	lkml <linux-kernel@...r.kernel.org>, ericvh@...il.com,
	mfasheh@...e.com
Subject: Re: How do I printk <type> correctly?

On Wed, 29 Oct 2008 10:00:04 +0200 Artem Bityutskiy wrote:

> On Tue, 2008-10-28 at 16:11 -0700, Randy Dunlap wrote:
> > On Thu, 23 Oct 2008 15:41:33 +0400 Alexey Dobriyan wrote:
> > 
> > > If variable is of Type	use	printk format specifier.
> > > ---------------------------------------------------------
> > > 		int			%d or %x
> > > 		unsigned int		%u or %x
> > > 		long			%ld ot %lx
> > > 		unsigned long		%lu or %lx
> > > 		long long		%lld or %llx
> > > 		unsigned long long	%llu or %llx
> > > 		size_t			%zu or %zx
> > > 		ssize_t			%zd or %zx
> > > 
> > > Raw pointer value SHOULD be printed with %p.
> > > 
> > > u64 SHOULD be printed with %llu/%llx, (unsigned long long):
> > > 
> > > 	printk("%llu", (unsigned long long)u64_var);
> > > 
> > > s64 SHOULD be printed with %lld/%llx, (long long):
> > > 
> > > 	printk("%lld", (long long)s64_var);
> > > 
> > > If type is dependent on config option (sector_t), use format specifier
> > > of biggest type and explicitly cast to it.
> > > 
> > > Reminder: sizeof() result is of type size_t.
> 
> Do we have this somewhere in Documentation? Would be nice to have it.

It's in the C standard, which we don't try to put into Documentation/ AFAIK.

section 6.5.3.4, The sizeof operator:

4 The value of the result is implementation-defined, and its type (an unsigned integer type)
is size_t, defined in <stddef.h> (and other headers).


---
~Randy
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