From mboxrd@z Thu Jan  1 00:00:00 1970
From: Timothy Redaelli <tredaelli@redhat.com>
Subject: Re: Build is broken in dpdk-next-net
Date: Fri, 30 Mar 2018 16:28:30 +0200
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Cc: Andrew Rybchenko <arybchenko@solarflare.com>, "dev@dpdk.org"
 <dev@dpdk.org>, Ferruh Yigit <ferruh.yigit@intel.com>, Thomas Monjalon
 <thomas@monjalon.net>, Tonghao Zhang <xiangxia.m.yue@gmail.com>
To: Maxime Coquelin <maxime.coquelin@redhat.com>
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On Fri, 30 Mar 2018 15:27:55 +0200
Maxime Coquelin <maxime.coquelin@redhat.com> wrote:

> Hi Andrew,
>=20
> On 03/30/2018 03:18 PM, Andrew Rybchenko wrote:
> > Hi all,
> >=20
> > Build is broken in dpdk-next-net for me on Ubuntu 16.04.4:
> >=20
> > lib/librte_vhost/fd_man.c: In function =E2=80=98fdset_pipe_read_cb=E2=
=80=99:
> > lib/librte_vhost/fd_man.c:284:2: error: ignoring return value of
> > =E2=80=98read=E2=80=99, declared with attribute warn_unused_result
> > [-Werror=3Dunused-result] read(readfd, charbuf, sizeof(charbuf)); ^
> > lib/librte_vhost/fd_man.c: In function =E2=80=98fdset_pipe_notify=E2=80=
=99:
> > lib/librte_vhost/fd_man.c:324:2: error: ignoring return value of
> > =E2=80=98write=E2=80=99, declared with attribute warn_unused_result
> > [-Werror=3Dunused-result] write(fdset->u.writefd, "1", 1); ^
> >=20
> > $ gcc --version
> > gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609 =20
>=20
> Thanks for reporting, I don't catch it with my Fedora build system:
> $ gcc --version
> gcc (GCC) 7.3.1 20180303 (Red Hat 7.3.1-5)

Those kind of warnings are enabled by "-D_FORTIFY_SOURCE=3D2" (enabled by
default in Ubuntu [1]).

To have the same behavior on Fedora you need to set -D_FORTIFY_SOURCE=3D2
by hand, for example with:

# make EXTRA_CFLAGS=3D"-D_FORTIFY_SOURCE=3D2"

Usually I build dpdk with the flags we also use when we build the
Fedora/RHEL package. To do that I have in my .bashrc (all in one line):

export EXTRA_CFLAGS=3D"-O2 -g -pipe -Werror=3Dformat-security
-Wp,-D_FORTIFY_SOURCE=3D2 -fexceptions -fstack-protector-strong
--param=3Dssp-buffer-size=3D4 -grecord-gcc-switches
-specs=3D/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=3Dgeneric
-fasynchronous-unwind-tables -Wformat"

> >=20
> > As I understand it is broken in
> > ad94ade905454401b705be9e06b19e54a1c78148 vhost: add pipe event for
> > optimizing negotiating =20
>=20
> I confirm it is this patch.
>=20
> Xiangxia, can you provide a fix please?
>=20
> Ferruh, how do you want to proceed?
> Would you revert it?
>=20
> Thanks,
> Maxime
> > Andrew.
> >  =20

[1]
https://wiki.ubuntu.com/ToolChain/CompilerFlags#A-D_FORTIFY_SOURCE.3D2