The default for RHEL5 is 32bit: http://www.ibm.com/developerworks/wikis/display/LinuxP/Performance+FAQs#PerformanceFAQs-WhyistheRHEL5defaultforapplications32bitandtheSLES11default64bit%3F The default for RHEL6 presumably changed to be 64bit like SLES11. To quote big blue (when talking about RHEL5): "It is logical that the next version of RHEL would likely move to a 64-bit default." -----Original Message----- From: crash-utility-bounces@xxxxxxxxxx [mailto:crash-utility-bounces@xxxxxxxxxx] On Behalf Of Dave Anderson Sent: Tuesday, June 26, 2012 11:23 PM To: Discussion list for crash utility usage, maintenance and development Subject: PPC64 compiler question While doing some testing I ran into a surprising crash-build bug on ppc64, where on a RHEL5 ppc64 host, a simple "make" command would build a 32-bit PPC crash utility. But on RHEL6, it built as 64-bit PPC64 crash utility as expected. (This was due to a crash-6.0.3 change to support "make target=PPC" on a ppc64 host). Anyway, the reason is that in the RHEL5 environment, if an application is compiled without specifying -m32 or -m64, it builds a 32-bit binary, whereas on RHEL6 it builds a 64-bit binary by default: RHEL5: # cat doit.c main() {} # gcc doit.c # file a.out a.out: ELF 32-bit MSB executable, PowerPC or cisco 4500, version 1 (SYSV), for GNU/Linux 2.6.9, dynamically linked (uses shared libs), not stripped # gcc --version gcc (GCC) 4.1.2 20080704 (Red Hat 4.1.2-52) Copyright (C) 2006 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. # uname -r 2.6.18-308.el5 # RHEL6: # cat doit.c main() {} # gcc doit.c # file a.out a.out: ELF 64-bit MSB executable, 64-bit PowerPC or cisco 7500, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.18, not stripped # gcc --version gcc (GCC) 4.4.6 20110731 (Red Hat 4.4.6-3) Copyright (C) 2010 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. # uname -r 2.6.32-220.el6.ppc64 # What controls that? Is it the compiler, some environment setting, or what? Dave -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility -- Crash-utility mailing list Crash-utility@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/crash-utility