 
![Fatdog64 logo](img/fatdog64-header.png)


# How to build a kernel for Fatdog

This is an example for building/compiling a kernel for Fatdog from scratch. It assumes you already know your way around Fatdog and Linux in general.  
This however is neither a tutorial nor a comprehensive instructions to build the kernel which ships with Fatdog. This is only an example, and it covers only the *minimal* steps you need to do create, and package, the most basic kernel that is capable of booting Fatdog. There are additional steps not explained here (e.g. building aufs utilities, or external / third party kernel modules) because they only cause distraction and do not add to the pedagogical value of this example. Building an additional external kernel module for example is covered [here](kernel-module.md).  
In this example, we will build the **4.19.319** kernel. At the time of writing, 4.19.319 is the most recent version of the 4.19 LTS (long-term-supported) kernel. It is also the kernel line with the longest longevitiy, which makes it an ideal example as this kernel line would probably continue long after this document is written. Nevertheless, the same principles are applicable for all kernels, either older or newer. The only thing to be careful is to adjust the aufs patches to use(different kernel versons may have different patches to use).  

## Preparations

  
1. The most important step of the process: Obtain the known-good kernel configuration file from the kernel version *nearest* to the one that you want to build.  
The kernel configuration file is known as **.config** file, or in Puppy's terms, the **DOTconfig**.  
In Fatdog, this file can be obtained in two ways:  
a) from the running kernel, by running the command **zcat /proc/config.gz \> DOTconfig**  
b) from kernel-source-X.Y.Z.sfs; this file is located in **/usr/src/linux-X.Y.Z/.config**  
For this example I will take the **.config** from **kernel-source-4.19.92.sfs** (from here: <http://distro.ibiblio.org/fatdog/sfs/800/>)  
2. Obtain the known-good firmware collection for a kernel version which is *nearest* to the one that you're building.  
This is normally located in kernel-modules.sfs, located in **/lib/firmware**. If you're being lazy, then just download one of the tarballs from here: <https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git>, but that file will be huge (linux-firmware-20240811.tar.gz for example is 555 MB) as it will include firmware from all kernel versions back to version 2.6 onwards. The point of using existing firmware collection is to include only the firmware that you need, to make the size smaller.  
For this example I will use the firmware from **kernel-modules.sfs-4.19.92** (from here: <http://distro.ibiblio.org/fatdog/kernels/800/>)  
3. Have a Linux partition ready. Building kernel requires a lot of space which probably won't fit into your RAM, or your savefile/savefolder, so do it in an external Linux partition (it has to be a **Linux** partition, not FAT32, NTFS or anything like that).  
For this example, I will use **/mnt/sdc1** as the location (**/mnt/sdc1** is the mountpoint of **/dev/sdc1**, which is my external USB drive containing an ext4 partition).  
The rest of the steps will be shown one line at a time, and without commentaries except when it is absolutely necessary (comments are prefixed by \#).  

## Steps

  


``` 
cd /mnt/sdc1

# get and unpack kernel sources
wget https://cdn.kernel.org/pub/linux/kernel/v4.x/linux-4.19.319.tar.xz
tar -xvf linux-4.19.319.tar.xz
cd linux-4.19.319

# get aufs and apply aufs patches
git clone https://github.com/sfjro/aufs4-standalone
cd aufs4-standalone
git checkout aufs4.19.63+
cp -r Documentation/ fs/ ..
cp include/uapi/linux/aufs_type.h ../include/uapi/linux/
cd ..
patch -Np1 -i aufs4-standalone/aufs4-kbuild.patch
patch -Np1 -i aufs4-standalone/aufs4-base.patch
patch -Np1 -i aufs4-standalone/aufs4-mmap.patch
patch -Np1 -i aufs4-standalone/aufs4-loopback.patch
patch -Np1 -i aufs4-standalone/vfs-ino.patch
patch -Np1 -i aufs4-standalone/tmpfs-idr.patch
patch -Np1 -i aufs4-standalone/proc_mounts.patch

# get .config
mount /path/to/kernel-source-4.19.92.sfs /mnt/data
cp /mnt/data/usr/src/linux-4.19.92/.config .config
umount /mnt/data

# apply .config
yes "" | make oldconfig
# if you want to, you can adjust your kernel configuration by running:
# make menuconfig

# go for coffee
make -j4 bzImage modules

# install and prepare modules
make modules_install INSTALL_MOD_PATH=modules
depmod -a -b modules 4.19.319

# create kernel-source links for dkms
ln -s /usr/src/linux-4.19.319 modules/lib/modules/4.19.319/build
ln -s /usr/src/linux-4.19.319 modules/lib/modules/4.19.319/source

# copy firmware
mkdir -p modules/lib/firmware
mount /path/to/kernel-modules.sfs-4.19.92 /mnt/data
cp -a /mnt/data/lib/firmware/* modules/lib/firmware
umount /mnt/data

# package kernel-modules.sfs and vmlinuz
mksquashfs modules kernel-modules.sfs -noappend -comp xz
cp arch/x86/boot/bzImage vmlinuz
```


The **vmlinuz** and **kernel-modules.sfs** will be in your kernel build directory. In this example, it will be in **/mnt/sdc1/linux-4.19.319**.  
This document was originally posted [The Puppy Linux Forum](https://forum.puppylinux.com/viewtopic.php?p=129001#p129001).  


----

[Fatdog64](home.md)
| [FAQ index](faq.md)
| [FAQ files](faq_file_list.md)
| [Fatdog64 online](https://distro.ibiblio.org/fatdog/web)
| [FAQ online](https://distro.ibiblio.org/fatdog/web/faqs/faq.html)

----

_This page was automatically converted from [kernel-build.html](https://distro.ibiblio.org/fatdog/web/faqs/kernel-build.html) on 2025-09-20._
