Re: [PATCH v9 1/1] net/af_xdp: introduce AF XDP PMD driver

[Ye Xiaolong <xiaolong.ye@intel.com>]

On 04/03, Bruce Richardson wrote:
>On Wed, Apr 03, 2019 at 11:14:58PM +0800, Ye Xiaolong wrote:
>> On 04/03, Luca Boccassi wrote:
>> >On Wed, 2019-04-03 at 22:43 +0800, Ye Xiaolong wrote:
>> >> On 04/03, Luca Boccassi wrote:
>> >> [snip]
>> >> > > Got it.
>> >> > > 
>> >> > > In above steps, 'libbpf' also build from kernel source tree, will
>> >> > > it
>> >> > > be problem
>> >> > > in you builds to not have it build from source?
>> >> > > 
>> >> > > If not, taking into account that xsk.h also will be fixed, only
>> >> > > 'tools/include/asm/barrier.h' remains the problem, and it looks
>> >> > > like
>> >> > > it can be
>> >> > > solved, please check above.
>> >> > 
>> >> > libbpf is already packaged separately in Debian and I think other
>> >> > distros will follow soon, so it's all good for me once the barrier
>> >> > issue is solved.
>> >> > 
>> >> > https://packages.debian.org/buster/libbpf-dev
>> >> > 
>> >> > 
>> >> > From the makefile's perspective it should not matter where it comes
>> >> > from - the headers should be expected to be in /usr/include and the
>> >> > library in /usr/lib* - and pkg-config can help with that if
>> >> > available.
>> >> > And if a user wants to use a custom path, then it's no different
>> >> > than
>> >> > any of the other dependencies on other external libraries
>> >> 
>> >> From tools/lib/bpf/Makefile, after make install_lib and make
>> >> install_headers,
>> >> the headers and library would be put in /usr/local/include/bpf and
>> >> /usr/local/lib*,
>> >> Is it ok?
>> >
>> >Yes certainly that's fine, that's expected for local installations, and
>> >users can specify a prefix with the upstream's makefile if they want to
>> >install somewhere else.
>> 
>> In my local test, if I run `make install_lib` to install the libbpf.so to 
>> /usr/local/lib64, `-lbpf` specified in af_xdp pmd still fails to find the library,
>> the build would end up with a lot of undefined references which are defined in libbpf.
>> It means during dpdk compilation, it won't search libraries in /usr/local/lib*, right?
>> 
>> Install the libbpf to /usr/lib64 via `make install_lib prefix=/usr` doesn't have 
>> this issue, so shall I just document it in af_xdp.rst or there is other proper
>> way to do it?
>> 
>At a guess I'd say you are using Fedora Linux, right? Fedora is unusual in
>that it doesn't by default add /usr/local to the library and header search
>paths so you need to explicitly add them to your environment. Other distros
>should work fine for this.

I am using centos 7.4, I guess it has the same issue as Fedora you mentioned 
above.

Thanks,
Xiaolong
>
>/Bruce