Re: [OE-core] unwanted linux kernel image added to /boot directory

["Denys Dmytriyenko" <denis@denix.org>]

This went off the list - hope you don't mind to put it back...


On Tue, Mar 16, 2021 at 10:58:22AM -0700, Scott Branden wrote:
> Hi Denys,
> 
> Thanks for the excellent suggestions - they work.
> But, these seem really obscure.  I think the kernel.bbclass shouldn't automatically
> be installing /boot/linux to begin with.  It could be done based on an image feature
> selection?

kernel.bbclass does not populate the rootfs, it populates the corresponding 
package. Any rootfs/initramfs is then built by installing necessary packages 
into it. Whether to install a package or not is determined by IMAGE_INSTALL 
and dependencies between the packages.


> In addition, there seems to be an additional logic error in the present image
> creation.  If I do not install an external kernel module in the image then /boot/linux
> is not installed either.  Simply adding an external kernel module to an image shouldn't
> pull in /boot/linux into the image?

It is not an error, but a well-defined behavior. In the link below there's a 
comment about the default dependencies and how to alter them.

Basically, every kernel-module-* RDEPENDS on kernel-base, which normally 
RDEPENDS on kernel-image. So, when you insall a module into your rootfs, it 
follows the dependency chain properly. Hence all the suggestions you received 
to simply disconnect kernel-image from kernel-base.

That normally works for most cases, unless you need a mixed behavior that I 
mentioned. Hence, ROOTFS_POSTPROCESS_COMMAND trick.


> On 2021-03-15 4:57 p.m., Denys Dmytriyenko wrote:
> > On Mon, Mar 15, 2021 at 04:39:56PM -0700, Scott Branden via lists.openembedded.org wrote:
> >> Hello,
> >>
> >> There seems to be a problem when a kernel module is added to an initramfs 
> >> image.
> >>
> >> As soon as I add a recipe which installs an external kernel module into an 
> >> initramfs image it automatically installs the linux kernel image in a /boot 
> >> directory.
> >>
> >> This is really bad as it increases the size of the initramfs image.
> >>
> >> /boot/Image should not be installed in the image when an external kernel 
> >> module is added to an image.
> >>
> >> Can someone suggest a fix to this issue?
> > 
> > There is an ages-old control knob for that, read here:
> > https://git.openembedded.org/openembedded-core/tree/meta/classes/kernel.bbclass#n623
> > 
> > In your machine or distro config, you can set this as:
> > RDEPENDS_${KERNEL_PACKAGE_NAME}-base = ""
> > 
> > But that will affect all your images for a given machine. If you need to only 
> > do it selectively for your initramfs image, but keep the standard behavior for 
> > other images, you can do something like this in corresponding recipe:
> > 
> > ROOTFS_POSTPROCESS_COMMAND += "empty_boot_dir; "
> > empty_boot_dir () {
> >         rm -rf ${IMAGE_ROOTFS}/boot/*
> > }

-- 
Regards,
Denys Dmytriyenko <denis@denix.org>
PGP: 0x420902729A92C964 - https://denix.org/0x420902729A92C964
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