[bitbake-devel] [yocto] Question about shipping files to package.

[McKay, Sean]

I’m not an expert on compiling kernel modules, but I can at least answer some of your questions to get started. I’m also not an actual expert, but just another user, so it’s entirely possible that someone more knowledgeable will come along and tell us that I’m wrong.

With that said, first, I have to ask the simple stuff: when you say that no .ko is being created, where are you looking? If you’re not sure where you should be looking, I’d recommend by doing a find inside of your ${WORKDIR} to see whether or not you’ve got any .ko files. They won’t quite be out in plain sight.

In general (though again, I can’t speak for the module class), compilations take place in a build directory inside of the recipe’s workdir (${B} in bitbake parlance). The install process then copies the created files to a staging directory (${D} in bitbake parlance) that’s usually ${WORKDIR}/image.

Packaging is the process of taking those output files from ${D} and packaging them into one of a few well defined packaging formats. If you’re using the defaults, this would be RPM. A single recipe can (and often does) produce multiple packages. When bitbake moves onto the packaging step (I’m simplifying a bit), it creates directories for each package that’s going to be generated inside of ${WORKDIR}/packages-split. It then looks at the FILES variable for the particular package it’s working on and copies any files that match the patterns in that variable into that package’s directory in packages-split. When it’s done copying files, each of those directories are turned into the appropriate package (probably .rpm) file.
So, for a somewhat more concrete example, when you said ‘FILES_${PN} += "/lib/modules/4.1.8-rt8+gbd51baf"’, you told bitbake that anything that matched /lib/modules/4.1.8-rt8+gbd51baf should get put in the ${PN} (main) package.

In the context of the error message you were previously receiving, “installed” is the do_install step, which is referring to that staging process (analogous to running ‘make install’ on something you just downloaded from the internet). Something is ‘shipped’ if it is packaged into one of the final rpm files.

Cheers!
-Sean McKay

From: yocto at lists.yoctoproject.org <yocto at lists.yoctoproject.org> On Behalf Of Wayne Li
Sent: Thursday, December 5, 2019 2:26 PM
To: bitbake-devel <bitbake-devel at lists.openembedded.org>; Yocto Project Discussion <yocto at yoctoproject.org>
Subject: [yocto] Question about shipping files to package.

Dear Yocto Developers,

So I created a bitbake recipe to integrate kvm into my image as an out-of-tree kernel module.  Here's my recipe right now:

LICENSE = "GPLv2"
LIC_FILES_CHKSUM = "file://COPYING;md5=c616d0e7924e9e78ee192d99a3b26fbd"

inherit module

SRC_URI = "file:///homead/QorIQ-SDK-V2.0-20160527-yocto/sources/meta-virtualization/recipes-kernel/kvm-kmodule/kvm-kmod-3.10.21.tar.bz2"

S = "${WORKDIR}/kvm-kmod-3.10.21"

do_configure() {
    ./configure --arch=ppc64 --kerneldir=/homead/QorIQ-SDK-V2.0-20160527-yocto/build_t4240rdb-64b/tmp/work/t4240rdb_64b-fsl-linux/kernel-devsrc/1.0-r0/image/usr/src/kernel
}

FILES_${PN} += "/lib/modules/4.1.8-rt8+gbd51baf"

Bitbaking this recipe completes with no problems but no kernel module is created (compiling the source code should create a kernel module file kvm.ko).  I was wondering if the problem might be because of what I set FILES_${PN} to be.  Before I set the FILES variable I was getting an error saying something along the lines of, "Files/directories were installed but not shipped."  Then I more or less just guessed a directory and set my FILES variable to it and then the recipe finished bitbaking with no errors.

But now that the kvm.ko file isn't even being created, I am wondering if it might be because I set the FILES variable wrong?  What does the word "ship" mean?  And along those lines what exactly is a "package" in the setting of Yocto project?

-Thanks!, Wayne Li
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