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Date: Mon, 07 Mar 2022 13:12:14 +0100
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From: Paul Zimmermann <Paul.Zimmermann@inria.fr>
To: libc-alpha@sourceware.org
Subject: test old versions of glibc
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       Hi,

I have an application that I want to test with old versions of glibc.
The following usually works:

$ gcc -fno-builtin test_pow.c -lm
$ /localdisk/zimmerma/glibc-2.29/build/testrun.sh ./a.out
z=0x1.fffeb4d85aa15p-1010

However with glibc-2.28 it fails, because the binary contains a call to
pow@GLIBC_2.29:

$ nm a.out | grep pow
                 U pow@GLIBC_2.29

$ /localdisk/zimmerma/glibc-2.28/build/testrun.sh ./a.out
./a.out: /localdisk/zimmerma/glibc-2.28/build/math/libm.so.6: version `GLIBC_2.29' not found (required by ./a.out)

How can I disable the check for GLIBC_2.29 (this is for my particular
application, and I know what I'm doing)?

Best regards,
Paul

$ cat test_pow.c
#include <stdio.h>
#include <math.h>
int main()
{
  double x = 0x1.ffeffa651a733p-1;
  double y = 0x1.5d318bcd8f1f1p+22;
  double z = pow (x, y);
  printf ("z=%a\n", z);
  return 0;
}