Re: [dpdk-dev] [PATCH] devtools: fix 32-bits build

[Thomas Monjalon <thomas@monjalon.net>]

09/11/2020 14:35, Bruce Richardson:
> On Mon, Nov 09, 2020 at 01:24:28PM +0000, Ferruh Yigit wrote:
> > On 11/9/2020 1:19 PM, Thomas Monjalon wrote:
> > > 09/11/2020 14:00, Ferruh Yigit:
> > > > 32 bit still uses the pkgconfig file for 64-bits libraries, from the
> > > > build log:
> > > > 
> > > > "
> > > > Using DPDK_TARGET i386-pc-linux-gnu
> > > > meson  -Dexamples=l3fwd --buildtype=debugoptimized --werror
> > > > -Dc_args=-m32 -Dc_link_args=-m32
> > > > /tmp/dpdk_maintain/self/dpdk/devtools/.. ./build-32b
> > > > ...
> > > > Using 'PKG_CONFIG_PATH' from environment with value:
> > > > '/usr/local/lib64/pkgconfig/
> > > > "
> > > > 
> > > > This causes build error when linking with the found libraries.
> > > > 
> > > > Reproduced with 'librte_bpf' which only has 64 bit installed but still
> > > > enables building 'af_xdp' and link fails.
> > > 
> > > I think it is a problem in your configuration.
> > > PKG_CONFIG_PATH is not empty before starting the script, right?
> > > 
> > > > To fix updating 'PKG_CONFIG_PATH' and preventing 'load_env' overwrite
> > > > it.
> > > [...]
> > > > 'build-32b' check inside the 'load_env' looks ugly but not sure how to
> > > > be sure 'PKG_CONFIG_PATH' set correct.
> > > [...]
> > > > -	export PKG_CONFIG_PATH=$default_pkgpath
> > > > +	if [ "$targetdir" != "build-32b" ] ; then
> > > > +		export PKG_CONFIG_PATH=$default_pkgpath
> > > > +	fi
> > > 
> > > You can reset PKG_CONFIG_PATH in your config file.
> > > Something like this:
> > > 
> > > if echo $DPDK_TARGET | grep -q '^i[3-6]86' ; then
> > > 	export PKG_CONFIG_PATH=my32bitlibs/pkgconfig
> > > fi
> > > 
> > > We can also discuss why inheriting some default values on script start
> > > instead of just resetting them.
> > > 
> > 
> > Yes I have 'PKG_CONFIG_PATH' set in my environment before running script, if
> > it expects it to be not set, +1 to reset it at the beginning of the script.
> 
> +1 to this, because we can't have a global PKG_CONFIG_PATH for both 32-bit
> and 64-bit builds.

Not sure what is best.
The idea of saving the env vars is to consider what the user set
for one run, not in the config file:

default_path=$PATH
default_pkgpath=$PKG_CONFIG_PATH
default_cppflags=$CPPFLAGS
default_cflags=$CFLAGS
default_ldflags=$LDFLAGS

Do you want to change this assumption to ignore all environment vars?
Should we save PATH at least?
Do we set every variables inside the configuration file?

I tend to think that it may be safer to avoid influence of the env
and have a self-contained config file.
So I would add PATH=/usr/bin at the beginning of my config file.