linux-kernel - Re: [PATCH 03/22] tools lib traceevent: Add traceevent_host

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Date:	Mon, 25 Nov 2013 10:33:59 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Steven Rostedt <rostedt@...dmis.org>, linux-kernel@...r.kernel.org,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>, Paul Mackerras <paulus@...ba.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Arnaldo Carvalho de Melo <acme@...hat.com>,
	David Ahern <dsahern@...il.com>
Subject: Re: [PATCH 03/22] tools lib traceevent: Add
 traceevent_host_bigendian function

On Mon, Nov 25, 2013 at 04:24:52PM +0900, Namhyung Kim wrote:
> Hi Steve,
> 
> On Sat, 23 Nov 2013 03:27:08 -0500, Steven Rostedt wrote:
> > On Fri, 22 Nov 2013 23:22:52 +0900
> > Namhyung Kim <namhyung@...nel.org> wrote:
> >
> >> 2013-11-21 (목), 12:01 +0100, Jiri Olsa:
> >> > Adding traceevent_host_bigendian function to get host
> >> > endianity. It's used in following patches.
> >> 
> >> [SNIP]
> >> > +static inline int traceevent_host_bigendian(void)
> >> > +{
> >> > +	unsigned char str[] = { 0x1, 0x2, 0x3, 0x4 };
> >> > +	unsigned int *ptr;
> >> > +
> >> > +	ptr = (unsigned int *)str;
> >> > +	return *ptr == 0x01020304;
> >> 
> >> Is it safe for every architecture supported - especially ones that
> >> require stricter alignment?  I know many architectures/compilers align
> >> stack but not sure doing this is safe for all architecture.
> >
> > Would you prefer this (I tested it on both a big and little endian)
> >
> > {
> > 	unsigned char str[] = { 0x1, 0x2, 0x3, 0x4 };
> > 	unsigned int val;
> >
> > 	memcpy(&val, str, 4);
> > 	return val == 0x01020304;
> > }
> 
> Yeah, looks good to me.

ok, will change to this one

thanks,
jirka
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