Re: [PATCH v3] docs: describe how to quickly build a trimmed kernel

[Bagas Sanjaya <bagasdotme@gmail.com>]

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On Sun, Mar 05, 2023 at 02:04:44PM +0100, Thorsten Leemhuis wrote:
> +.. _patching_sbs:
> +
> + * In case you want to apply a kernel patch, do so now. Often a command like
> +   this will do the trick::
> +
> +     patch -p1 < ../proposed-fix.patch
> +
> +   If the ``-p1`` is actually needed, depends on how the patch was created; in
> +   case it does not apply thus try without it.
> +
> +   If you cloned the sources with git and anything goes sideways, run ``git
> +   reset --hard`` to undo any changes to the sources.

Alternatively, if you have ``b4`` installed, you can prepare the patch
with ``b4 am -l <message-id of the patch>``. The -l option adds a Link:
to lore.kernel.org for the patch. Apply the resulting patch with
``git am``.

It is often wise to branch-off from mainline before applying patches, to
keep the remote-tracking mainline pristine. Create a branch with ``git
checkout -b <branch name>``.

> +Changes merged into the mainline repository are only synced to the master branch
> +of the Linux stable repository  every few hours. This lag most of the time is
> +not something to worry about; but in case you really need the latest code, just
> +add the mainline repo as additional remote and checkout the code from there::
> +
> +    git remote add mainline \
> +      https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> +    git fetch mainline
> +    git checkout --detach mainline/master

You will most likely change the tracking remote for your master branch
to mainline by ``git branch --set-upstream-to=mainline/master``.

> +The step-by-step guide uses the default make targets (e.g. 'bzImage' and
> +'modules' on x86) to build the image and the modules of your kernel, which later
> +steps of the guide then install. You instead can also directly build everything
> +and directly package it up by using one of the following targets:
> +
> + * ``make -j $(nproc --all) bindeb-pkg`` to generate a deb package
> +
> + * ``make -j $(nproc --all) binrpm-pkg`` to generate a rpm package
> +
> + * ``make -j $(nproc --all) tarbz2-pkg`` to generate a bz2 compressed tarball

I used to try compiling kernel in rpm-based systems (at that time
CentOS). make binrpm-pkg generates kernel headers, image, and sanitized
kernel headers for libc packages. These three packages have to be
installed together. However, the generated libc headers package most
likely overwrite distro-installed one, thus rebuilding the world is
necessary. I mind of that significant overhead, so I proceed to manually
install the kernel.

Thanks.  

-- 
An old man doll... just what I always wanted! - Clara

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