Re: Build is broken in dpdk-next-net

[Timothy Redaelli <tredaelli@redhat.com>]

On Fri, 30 Mar 2018 15:27:55 +0200
Maxime Coquelin <maxime.coquelin@redhat.com> wrote:

> Hi Andrew,
> 
> On 03/30/2018 03:18 PM, Andrew Rybchenko wrote:
> > Hi all,
> > 
> > Build is broken in dpdk-next-net for me on Ubuntu 16.04.4:
> > 
> > lib/librte_vhost/fd_man.c: In function ‘fdset_pipe_read_cb’:
> > lib/librte_vhost/fd_man.c:284:2: error: ignoring return value of
> > ‘read’, declared with attribute warn_unused_result
> > [-Werror=unused-result] read(readfd, charbuf, sizeof(charbuf)); ^
> > lib/librte_vhost/fd_man.c: In function ‘fdset_pipe_notify’:
> > lib/librte_vhost/fd_man.c:324:2: error: ignoring return value of
> > ‘write’, declared with attribute warn_unused_result
> > [-Werror=unused-result] write(fdset->u.writefd, "1", 1); ^
> > 
> > $ gcc --version
> > gcc (Ubuntu 5.4.0-6ubuntu1~16.04.9) 5.4.0 20160609  
> 
> 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=2" (enabled by
default in Ubuntu [1]).

To have the same behavior on Fedora you need to set -D_FORTIFY_SOURCE=2
by hand, for example with:

# make EXTRA_CFLAGS="-D_FORTIFY_SOURCE=2"

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="-O2 -g -pipe -Werror=format-security
-Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector-strong
--param=ssp-buffer-size=4 -grecord-gcc-switches
-specs=/usr/lib/rpm/redhat/redhat-hardened-cc1 -m64 -mtune=generic
-fasynchronous-unwind-tables -Wformat"

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

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