[dpdk-dev] Build is broken in dpdk-next-net

[Maxime Coquelin]

On 03/30/2018 04:28 PM, Timothy Redaelli wrote:
> On Fri, 30 Mar 2018 15:27:55 +0200
> Maxime Coquelin <maxime.coquelin at 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"

Thanks for the hint! I indeed reproduce with -D_FORTIFY_SOURCE=2
Maxime

>>>
>>> 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
>