[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <20091219143425.GA5003@nowhere>
Date: Sat, 19 Dec 2009 15:34:29 +0100
From: Frederic Weisbecker <fweisbec@...il.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: Ingo Molnar <mingo@...e.hu>, LKML <linux-kernel@...r.kernel.org>,
Arnaldo Carvalho de Melo <acme@...hat.com>,
Paul Mackerras <paulus@...ba.org>
Subject: Re: [PATCH] perf tools: Prevent from BITS_PER_LONG redefinition
On Sat, Dec 19, 2009 at 10:26:07AM +0100, Peter Zijlstra wrote:
> On Fri, 2009-12-18 at 23:05 +0100, Frederic Weisbecker wrote:
> > +#ifndef BITS_PER_LONG
> > /* CHECKME: Not sure both always match */
> > #define BITS_PER_LONG __WORDSIZE
> > +#endif
>
> Why use __WORDSIZE if you're not sure?
>
> (8*sizeof(long)) is simple and unambiguous.
Yeah but we need it from the CPP level.
We include such code located in kernel headers:
static __always_inline unsigned long __fls(unsigned long word)
{
int num = BITS_PER_LONG - 1;
#if BITS_PER_LONG == 64
if (!(word & (~0ul << 32))) {
num -= 32;
word <<= 32;
}
#endif
if (!(word & (~0ul << (BITS_PER_LONG-16)))) {
num -= 16;
word <<= 16;
}
And sizeof() is not defined :)
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists