Re: [dpdk-dev] [PATCH v6] doc: add meson ut info in prog guide

["Parthasarathy, JananeeX M" <jananeex.m.parthasarathy@intel.com>]

Hi,

>-----Original Message-----
>From: Bruce Richardson [mailto:bruce.richardson@intel.com]
>Sent: Monday, July 22, 2019 7:23 PM
>To: Thomas Monjalon <thomas@monjalon.net>
>Cc: Parthasarathy, JananeeX M <jananeex.m.parthasarathy@intel.com>;
>dev@dpdk.org; Michael Santana Francisco <msantana@redhat.com>; Aaron
>Conole <aconole@redhat.com>; Hari Kumar Vemula
><hari.kumarx.vemula@intel.com>; Pattan, Reshma
><reshma.pattan@intel.com>; Mcnamara, John <john.mcnamara@intel.com>;
>Kovacevic, Marko <marko.kovacevic@intel.com>; David Marchand
><david.marchand@redhat.com>
>Subject: Re: [dpdk-dev] [PATCH v6] doc: add meson ut info in prog guide
>
>On Mon, Jul 22, 2019 at 02:53:34PM +0200, Thomas Monjalon wrote:
>> 22/07/2019 14:39, Parthasarathy, JananeeX M:
>> >From: Michael Santana Francisco [mailto:msantana@redhat.com]
>> > >On Mon, Jul 8, 2019 at 4:18 PM Aaron Conole <aconole@redhat.com>
>wrote:
>> > >> Thomas Monjalon <thomas@monjalon.net> writes:
>> > >> >> +Building and running the unit tests
>> > >> >> +-----------------------------------
>> > >> >> +
>> > >> >> +* Create the meson build output folder using the following
>command::
>> > >> >> +
>> > >> >> +      $ meson <build_dir>
>> > >> >> +
>> > >> >> +* Enter into build output folder, which was created by above
>command::
>> > >> >> +
>> > >> >> +      $ cd build
>> > >> >
>> > >> > Should be the same as above: <build_dir>
>> >
>> > Will change accordingly.
>> >
>> > >> >
>> > >> >> +
>> > >> >> +* Compile DPDK using command::
>> > >> >> +
>> > >> >> +      $ ninja
>> > >> >
>> > >> > Do we really need to repeat above basic steps?
>> > >> > Would be easier to just reference another guide about meson.
>> > >> > I think doc/build-sdk-meson.txt should be moved to .rst.
>> > >>
>> > >> +1
>> >
>> > This doc helps to run UT, having basic steps in same page will help user to
>go through together and execute the same.
>> > Just for few lines moving back and forth to different pages might be bit
>confusing.
>> > Anyway still if you would prefer to remove these then only 2 sections will
>be available in this doc.
>> > Please let us know if it is ok.
>>
>> I think it is better to avoid repetition.
>>
>>
>> > >> >> +*  Multiple paths::
>> > >> >> +
>> > >> >> +       $ CFLAGS=-I/path1 -I/path2 meson build
>> > >> >
>> > >> > Some quotes are missing to set multiple paths.
>> >
>> > Is <build_dir>  meant here?
>>
>> I am just saying that space-separated value require some quotes.
>>
>> > >> >> +Below are some examples that show how to export libraries and
>> > >> >> +their header paths.
>> > >> >> +
>> > >> >> +To specify a single library at a time::
>> > >> >> +
>> > >> >> +    $ export LIBRARY_PATH=/root/wireless_libs/zuc/
>> > >> >> +    $ CFLAGS=-I/root/wireless_libs/zuc/include meson build
>> > >> >> +
>> > >> >> +To specify multiple libraries at a time::
>> > >> >> +
>> > >> >> +    $ export LIBRARY_PATH=/path/zuc/:/path/libsso_kasumi/build/
>> > >> >> +    $ CFLAGS=-I/path/zuc/include \
>> > >> >> +             -I/path/libsso_kasumi/include \
>> > >> >> +         meson build
>> > >> >
>> > >> > Why export is used for LIBRARY_PATH and not CFLAGS?
>> > >> > I think both variables can be exported or prepend the meson
>command?
>> >
>> > CFLAGS given in meson command works and  also CFLAGS can be
>exported.
>> > LIBRARY_PATH  cannot be prepended to meson command. We tried but it
>is not reflecting the required values.
>> > Environment variables set using export is considered and not as command
>line args of meson command.
>>
>> Please we need to understand why LIBRARY_PATH is not working when
>> preprended in the meson command.
>> Do you have more informations?
>>
>
>Rather than using the environment, one can also use "-Dc_args='...'
>-Dc_link_args='...'" when calling meson.
>
>Otherwise, I agree with Thomas, we should find out why the LIBRARY_PATH
>doesn't work when passed in directly. I'm not aware of any reason it shouldn't
>work.
>
>/Bruce

As per our earlier analysis,  

LDFLAGS was not supported earlier in meson command.

find_library() is used to check whether the external dependency library exists or not in order to configure the build.
This function uses the standard system path to check existence of library, or else LIBRARY_PATH can be used as environment variable for custom paths.
LIBRARY_PATH is not supported directly (not a build configure option).

Only recently we can observe that LDFLAGS support is included in meson and linker options can be provided using LDFLAGS.
$ CFLAGS=-fsomething LDFLAGS=-Wl,--linker-flag meson <options>

Although LDFLAGS can be used and build configuration gets updated in LINK_ARGS,

'dependencies' option of static_library and shared_library() should be an object which is return value from dependency()/find_library().
Due to use of find_library() currently, we need to set the environment variable.

Regards
M.P.Jananee