Date: Thu, 24 Mar 2005 14:10:31 -0800 From: Sean McNeil <sean@mcneil.com> To: freebsd-amd64@freebsd.org Subject: Re: undefined reference to `memset' Message-ID: <1111702231.2655.6.camel@server.mcneil.com> In-Reply-To: <20050324214956.GA99087@dragon.NUXI.org> References: <IDVJ3H01.CW0@hadar.amcc.com> <20050324214956.GA99087@dragon.NUXI.org>
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On Thu, 2005-03-24 at 13:49 -0800, David O'Brien wrote:
> Please don't top-post -- it destroys context. [Format recovered]
>
> On Thu, Mar 24, 2005 at 12:46:41PM -0800, Vinod Kashyap wrote:
> > > On Thu, Mar 24, 2005 at 06:05:17PM +1100, Peter Jeremy wrote:
> > > > On Wed, 2005-Mar-23 13:48:04 -0800, Vinod Kashyap wrote:
> > > > >If any kernel module has the following, or a similar line in it:
> > > > >-----
> > > > >char x[100] = {0};
> > > > >-----
> > > > >building of the GENERIC kernel on FreeBSD 5 -STABLE for amd64
> > > > >as of 03/19/05, fails with the following message at the
> > > time of linking:
> > > > >"undefined reference to `memset'".
> > > > >
> > > > >The same problem is not seen on i386.
> > > > >
> > > > >The problem goes away if the above line is changed to:
> > > > >-----
> > > > >char x[100];
> > > > >memset(x, 0, 100);
> > > > >-----
> > > >
> > > > Can you post a complete (compilable) example please.
> > >
> > > Vinod can you please post a complete compilable example?
> > > It is impossible to get anything done about your issue without stand
> > > alone test code.
> > Ok, make sure you have 'device twa' in your kernel configuration
> > file, and apply these patches to /sys/dev/twa/twa.c.
> > This patch causes the problem:
>
> "stand alone" means a single foo.c file that shows the problem you want
> fixed.
> I cannot submit a GCC bug report with a tarball of the entire FreeBSD
> kernel.
I've taken the liberty to write up an example here. Not sure if this is
a bug or not:
cc -O -pipe -c -fno-builtin -ffreestanding memset_bug.c
Take a look at what is generated:
objdump --disassemble memset_bug.o
You'll see that instead of performing the inline code generation for
memset, the compiler generates a call to memset in the case of the
assignment of {0}.
memset_bug.c:
#include <sys/types.h>
static __inline void *
memset(void *b, int c, size_t len)
{
char *bb;
if (c == 0)
bzero(b, len);
else
for (bb = (char *)b; len--; )
*bb++ = c;
return (b);
}
void bug (void)
{
int buf[100] = { 0 };
memset (buf, sizeof(buf), 0);
printf ("%d\n", buf[0]);
}
Attached as well.
Cheers,
Sean
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