Re: Begin: Mounting root file system ... /init: line 221: arithmetic syntax error

[John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>]

Hi Dennis,

On Fri, 2025-09-05 at 14:32 -0400, Dennis Clarke wrote:
> > I would suggest to create sparc64 sid chroot with the debootstrap command I suggested in my previous mails.
> > 
> > Just make sure to install qemu-user before running it with »--arch=sparc64« on your x86_64 machine.
> > 
> 
> I have no idea how to do these things. I am guessing the qemu-user stuff
>   is for some cross compile procedure ?

No, it's not that difficult. qemu-user is a variant of QEMU that allows you to run
single binaries of a foreign architecture on your x86_64 machine as if it was a
native binary.

For example, you could download a static sparc64 binary, run it with

	qemu-user-sparc64 /path/to/binary

and it would just work.

Now, debootstrap is the command to create the directory structure of a minimum Debian
system into a directory, also called chroot. The chroot contains a fully working system
that you could then copy into the root directory of an empty partition and use this as
a new system partition to build your own Debian system from scratch.

debootstrap has basically this syntax:

# debootstrap --param1 --param2 --param3 --arch=$ARCH $DIST $DIR $MIRROR

where param1, param2, paramN are various parameters and:

- $ARCH - target architecture, e.g. sparc64
- $DIST - target distribution, e.g. unstable
- $DIR  - target directory, e.g. /tmp/sparc64-chroot
- $MIRROR - source mirror, e.g. http://ftp.ports.debian.org/debian-ports

debootstrap works by downloading set of fundamental deb packages for a target architecture
and extracts them into $DIR, this is called the first stage of debootstrap. After that
has happened, it tries to enter this chroot by running "chroot $DIR" and then install
additional packages and eventually configure all of them.

This would normally fail when the host architecture and the target architecture do not match
since your x86_64 CPU won't be able to execute sparc64. However, when you have the "qemu-user"
package installed, the Linux kernel can magically execute those sparc64 packages on your x86_64
machine without any additional configuration. It does that via the binfmt mechanism in the kernel
which can detect the executable format of a binary and automatically invoke it with the correct
interpreter, in our case ELF binaries for linux-sparc64 are automatically run with "qemu-user-sparc64".

To cut a long story short, run (as root):

# apt install qemu-user-binfmt debootstrap debian-ports-archive-keyring

Then:

# mkdir -p /path/to/sparc64/chroot # to create a target directory for the sparc64 chroot

and finally:

# debootstrap --keyring=/usr/share/keyrings/debian-ports-archive-keyring.gpg
              --include=debian-ports-archive-keyring,wget unstable /path/to/sparc64/chroot \
              http://ftp.ports.debian.org/debian-ports

After that, you will have a minimal sparc64 chroot in /path/to/sparc64/chroot.

You can even enter the chroot on your x86_64 machine with:

# chroot /path/to/sparc64/chroot

and then just run:

# apt update && apt install pkg1 pkg2 pkg3

to install any additional software.

Then tar this directory up:

# cd /path/to/sparc64/chroot
# tar czf ../sparc64-chroot.tgz .
# cd ..
# scp -r sparc64-chroot.tgz root@$IP_OF_YOUR_SPARC

On the SPARC machine, mount your new root partition:

# mount /dev/sdbN /mnt/ # /dev/sdbN being the root device of your new system disk

Enter it:

# cd /mnt/

Extract the tarball into it:

# tar xf /path/to/sparc64-chroot.tgz

And bind-mount /dev, /proc and /sys into it:

# mount -o bind /dev /mnt/dev
# mount -o bind /proc /mnt/proc
# mount -o bind /sys /mnt/sys

Enter the chroot:

# chroot /mnt/

Download the patched kernel:

# wget https://people.debian.org/~glaubitz/sparc64/linux-image-6.12.3-sparc64-smp_6.12.3-1+sparc64_sparc64.deb

And install it:

# apt update && apt install ./linux-image-6.12.3-sparc64-smp_6.12.3-1+sparc64_sparc64.deb

Leave the chroot:

# exit

Umount the bind-mounts:

# umount /mnt/{dev,proc,sys}

Copy the kernel and initrd from the chroot to where SILO can find them:

# cp -av /mnt/boot/vmlinux* /
# cp -av /mnt/boot/initrd* /

Then point your silo.conf to the new boot partition and reboot.

> > Then tar that directory up, transfer it to the SPARC and unpack it into the root directory of the second hard drive
> > 
> > Then point the root partition in silo.conf to the newly generated sid sparc64 partition.
> 
> That sounds cool ... if I can get there.

It's not that hard actually. I gave you the instructions above from memory, so it will
hopefully work for you, plus or minus some small corrections you may have to apply.

Adrian

-- 
 .''`.  John Paul Adrian Glaubitz
: :' :  Debian Developer
`. `'   Physicist
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