Re: [PATCH] rtla: Fix cross building

[Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>]

Hi,

Quoting Steven Rostedt (2023-02-01 20:31:44)
> On Fri, 20 Jan 2023 08:08:09 +0100
> Johannes Schauer Marin Rodrigues <josch@mister-muffin.de> wrote:
> 
> > For a successful cross-build, the host-architecture version of
> > pkg-config must be used or otherwise host architecture headers of
> > libtracefs and libtraceevent will not be found.
> > 
> > Signed-off-by: Johannes Schauer Marin Rodrigues <josch@mister-muffin.de>
> > ---
> >  tools/tracing/rtla/Makefile | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tools/tracing/rtla/Makefile b/tools/tracing/rtla/Makefile
> > index 22e28b76f800..26ebd46ec29c 100644
> > --- a/tools/tracing/rtla/Makefile
> > +++ b/tools/tracing/rtla/Makefile
> > @@ -18,7 +18,7 @@ endef
> >  $(call allow-override,CC,$(CROSS_COMPILE)gcc)
> >  $(call allow-override,AR,$(CROSS_COMPILE)ar)
> >  $(call allow-override,STRIP,$(CROSS_COMPILE)strip)
> > -$(call allow-override,PKG_CONFIG,pkg-config)
> > +$(call allow-override,PKG_CONFIG,$(CROSS_COMPILE)pkg-config)
> >  $(call allow-override,LD_SO_CONF_PATH,/etc/ld.so.conf.d/)
> >  $(call allow-override,LDCONFIG,ldconfig)
> >  
> 
> I don't usually have pkg-config as part of my cross build path. I have just
> overridden it to use different commands, by defining the variable of
> PKG_CONFIG, but I have not had any issues. But my compiler path never
> included pkg-config.

I found this problem when cross-compiling the linux Debian package. You can
find a build log (on amd64 for arm64) of how this fails on our Debian
crossbuild QA service:

https://crossqa.debian.net/build/linux_6.1.7-1_arm64_20230122165920.log

At the very bottom of that log you can see the following error message:

********************************************
** NOTICE: Failed build dependencies
**
** Required Libraries:
**   libtraceevent version 1.5 or higher
**   libtracefs version 1.3 or higher
**
** Consider installing the latest libtracefs from your
** distribution, e.g., 'dnf install libtraceevent-devel libtracefs-devel' on Fedora,
** or from source:
**
**  https://git.kernel.org/pub/scm/libs/libtrace/libtraceevent.git/ 
**  https://git.kernel.org/pub/scm/libs/libtrace/libtracefs.git/ 
**
********************************************

This error goes away after applying my patch. You can see that the both
libraries do get installed for arm64 at the top of the log. But they are not
found because the wrong pkg-config is used.

Thanks!

cheers, josch