[PATCH 3/4] makedumpfile: add -D_GNU_SOURCE to CFLAGS

HATAYAMA Daisuke d.hatayama at jp.fujitsu.com
Wed Apr 30 04:55:10 PDT 2014

From: Wang Nan <wangnan0 at huawei.com>
Subject: [PATCH 3/4] makedumpfile: add -D_GNU_SOURCE to CFLAGS
Date: Sat, 26 Apr 2014 12:07:08 +0800

> This patch is preparation for introduce pread/pwrite.

Do you explain more about _GNU_SOURCE? Did you need to define this on
your environment to build makedumpfile with pread/pwrite?

I tried to build a very simple test program using pread like

int main(void)
   printf("%p\n", pread);

on RHEL5.4, RHEL6.5 and fc20, and all were done successfully without
_GNU_SOURCE. They are all on x86_64.

I checked man pread and man pwrite on each environments for
_GNU_SOURCE but I didn't find it. What I found was _XOPEN_SOURCE
description only. For example this is man pread on RHEL6.5.

$ LANG=C man pread
PREAD(2)                   Linux Programmer's Manual                  PREAD(2)

       pread, pwrite - read from or write to a file descriptor at a given offset

       #define _XOPEN_SOURCE 500

       #include <unistd.h>

       ssize_t pread(int fd, void *buf, size_t count, off_t offset);

       ssize_t pwrite(int fd, const void *buf, size_t count, off_t offset);

Note that just as I said the above, building was successfully done on
this environment.


More information about the kexec mailing list