A chroot installation environment

Posted: 2022-09-10 | Author: slackalaxy | Filed under: system | Tags: chroot, vm |5 Comments

I have been having annoying problems with VirtualBox, summed up already at LQ, so I won’t go through them again. I need a clean installation of Slackware (x86_64 and x86), therefor, I decided to learn how to set it up in a chroot environment.

I used as a guide Slackware’s and CRUX’s wiki pages. Below is what I did for a 32bit Slackware on a 64bit “host”.

Create the folder, let’s name it slack32, where the chroot environment will be. I have a data storage HDD, mounted on /media/data0, so that’s where I decided to create it:

mkdir /media/data0/slack32/

Mount the installation ISO (as root, of course):

mount -o loop slackware-15.0-install-dvd.iso /media/cdrom0/

Navigate there, to the subfolder containing the packages:

cd /media/cdrom0/slackware/

Now, install all packages to the folder where we’ll chroot later:

installpkg --root /media/data0/slack32/ */*.t?z

Let’s already define the path to the folder as:

CHROOT=/media/data0/slack32/

Let’s navigate there:

cd $CHROOT

Copy resolv.conf from the host, so we have net:

cp /etc/resolv.conf $CHROOT/etc

There’s no fstab file, so let’s create one:

touch $CHROOT/etc/fstab

Paste these as it’s contents:

# <file system> <mount point>   <type>  <options>       <dump>  <pass>
tmpfs           /dev/shm        tmpfs    defaults        0      0
devpts          /dev/pts        devpts   noexec,nosuid,gid=tty,mode=0620  0      0
sysfs           /sys            sysfs    defaults        0      0
proc            /proc           proc     defaults        0      0

Now mount:

mount -t proc proc $CHROOT/proc

mount --bind /dev $CHROOT/dev

mount --bind /sys $CHROOT/sys

Finally, chroot there:

chroot $CHROOT /bin/bash

Specify that it’s a 32bit system:

linux32

From this point we are working in the chroot environment and all file locations are in the chroot environment. To set up slackpkg, a 32bit mirror should be selected. Since I installed from a 64bit host, the mirrors will be for x86_64 architecture. What I did was, first to modify a mirror close to me by removing the “64” suffix from “slackware:”

# FINLAND (FI)
ftp://elektroni.phys.tut.fi/slackware-15.0/

I had GPG signature problems, which seemed to disappear after I updated ca-certificates. For this, I had to stop the GPG check first:

# If CHECKGPG is "on", the system will verify the GPG signature of each package
# before install/upgrade/reinstall is performed.
CHECKGPG=off

Then, do

slackpkg update

slackpkg upgrade ca-certificates

After that, I put it back to on and then:

slackpkg update gpg

One thing that can also be done is to reinstall slackpkg itself, now when the system knows it’s 32bit, in this way all mirrors should be correct:

slackpkg reinstall slackpkg

Upgrade the whole system, as usual:

slackpkg upgrade-all

That’s it. I went to /tmp and tested a few SlackBuilds (Bpp1.9-*) that just made it back to 15.0. When done with working in slack32, I did:

exit

umount $CHROOT/proc

umount $CHROOT/dev

umount $CHROOT/sys

exit

Next time I need it, just start like this

CHROOT=/media/data0/slack32/

cd $CHROOT

mount -t proc proc $CHROOT/proc

mount --bind /dev $CHROOT/dev

mount --bind /sys $CHROOT/sys

chroot $CHROOT /bin/bash

linux32

Compile times are better than in a VM, that’s for sure. I also have very easy navigation and file sharing there. Phew!

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