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III ‐ Building the LFS System

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Nimpoo edited this page Aug 6, 2025 · 2 revisions

Introduction

Link to of where I am in the process - IV. Building the LFS System

Okay this part is really repetitive and time-consuming, you have over 100 packages to build, and you have to do it in a specific order. Here to, it's really impotant that all packages are built and installed correctly, otherwise you will run into issues later on.

1 - Packages Management

You're not built a packet manager, all packages are built and installed manually, and Gerard Beekmans is clear about this in the book. Read this section to see how you can manage the packages manually : Linux From Scratch - Version r12.3-95-systemd Chapter 8. Installing Basic System Software.

2 - Packages Building

If you're not in the chroot environment, you need to enter it first, and you need to mount virtual filesystems, AND the "physical" partition where you will build the packages, which is /mnt/lfs in our case. You can run my script here : mount_partitions_lfs.sh. Or you can do this with the following commands:

# ? Physical partition
mount -v -t ext4 /dev/sdb3 $LFS/
mount -v -t ext4 /dev/sdb2 $LFS/boot
mount -v -t vfat /dev/sdb1 -o codepage=437,iocharset=iso8859-1 $LFS/boot/efi
/sbin/swapon -v /dev/sdb4

# ? Virtual partition for debugging or something else
mount -v --bind /dev $LFS/dev

mount -vt devpts devpts -o gid=5,mode=0620 $LFS/dev/pts
mount -vt proc proc $LFS/proc
mount -vt sysfs sysfs $LFS/sys
mount -vt tmpfs tmpfs $LFS/run

if [ -h $LFS/dev/shm ]; then
  install -v -d -m 1777 $LFS$(realpath /dev/shm)
else
  mount -vt tmpfs -o nosuid,nodev tmpfs $LFS/dev/shm
fi

And enter the chroot environment:

chroot "$LFS" /usr/bin/env -i   \
    HOME=/root                  \
    TERM="$TERM"                \
    PS1='(lfs chroot) \u:\w\$ ' \
    PATH=/usr/bin:/usr/sbin     \
    MAKEFLAGS="-j$(nproc)"      \
    TESTSUITEFLAGS="-j$(nproc)" \
    /bin/bash --login

Be sure to build all the packages in the chroot environment.

Let's go on, I have a script here too, but I dicourage you from using it, you need to confirm after each package that it was built and installed correctly, and you need to check the logs. It's REALLY long, and not really automated:

And here we go, take care of all of your commands, check logs and run all the tests.

Talking about tests, sometimes you will run make test or make check to verify that the packages are functioning as expected. But sometimes, some packages can fail some tests, and if it happend check in the LFS book if the failure is expected or not. If it is, you can ignore it, otherwise you need to fix it (if you can, but good luck). And some tests are REALLY LONG, gcc for example takes (for me) around 30 minutes to run all the tests, so be patient. Or rush into the pile and skip the tests.

3 - Cleaning up

Wow fiou, that was long... If you want to strip the binaries, you can for free some space. I redirect you to the LFS book for this : Linux From Scratch - Version r12.3-95-systemd Chapter 8. Installing Basic System Software.

Clean up some extra files:

rm -rf /tmp/{*,.*}

For the same reasons as here, delete the .la files:

find /usr/lib /usr/libexec -name \*.la -delete

The compiler built previously is still partially installed and not needed anymore. Remove it with:

find /usr -depth -name $(uname -m)-lfs-linux-gnu\* | xargs rm -rf

And you can delete the user tester created in the previous section:

userdel -r tester

Almost done ! We need to configure some system files, compile GRUB and the Linux kernel and we'r done.

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