general/other Linux (Debian Bullseye) on FreeBSD

H

hruodr

I am not a friend of virtualization or emulation on the desktop, but I decided to try.
Linux is not a Thema in this forum, but the emulation :)

I did:

Code: 
# pkg install debootstrap
# mkdir /compat/debian
# kldload linux64
# debootstrap bullseye /compat/debian http://deb.debian.org/debian/
# chroot /compat/debian /bin/bash

And now I am trying to mount the virtual filesystem named in

docs.freebsd.org

Chapter 12. Linux Binary Compatibility

FreeBSD provides binary compatibility with Linux, allowing users to install and run most Linux binaries on a FreeBSD system without having to first modify the binary
docs.freebsd.org docs.freebsd.org

The following commandos fail (in the chroot):

Code: 
# mount -t sysfs sysfs /sys
mount: /sys: unknown filesystem type 'sysfs'.
# mount -t tmpfs tmpfs /dev/shm -osize=100m,mode=1777
mount: /dev/shm: unknown filesystem type 'tmpfs'.

And /dev/fd is filled without mounting anything.

I did apt-get install xterm, but get the error:

Code: 
# xterm
Warning: locale not supported by C library, locale unchanged
xterm: Error 32, errno 2: No such file or directory
Reason: get_pty: not enough ptys

and

Code: 
# mount -t devpts devpts /dev/pts
mount: /dev/pts: unknown filesystem type 'devpts'.
# ls /dev/pts/
0  1  2  3

Any hint?
 
You should mount emulated Linux virtual filesystems from the host, not from within the chroot (or jail). Set it up as a jail and mount virtual filesystems upon jail start; i.e. if using vanilla jails create /etc/fstab.debian like
Code: 
linsysfs   /srv/jails/debian/sys   linsysfs   auto  0  0
linprocfs  /srv/jails/debian/proc  linprocfs  auto  0  0
and in /etc/jail.conf
Code: 
debian {
    path = "/srv/jails/debian";
    ip4.addr = 192.168.1.77;
    exec.start = "/etc/init.d/rc 2";
    exec.stop = "/etc/init.d/rc 0";
    mount.fstab = /etc/fstab.debian;
    persist = true;
}
Then service jail start debian.
(partial example from an old Debian 8 jail, update jail.conf(5) to match to your setup).
 
Maybe this can give you ideas:
forums.freebsd.org

Setting up a (Debian) Linux jail on FreeBSD

Hi gang! Prerequisites: I am assuming that you know how to install software on FreeBSD and also have some basic understanding about FreeBSD jails. Editorial I'm going to be very honest here: I started disliking Linux for a while, and I've worked with it for a long time. For various reasons...
forums.freebsd.org forums.freebsd.org
 
hruodr said:
Code: 
# mount -t sysfs sysfs /sys
mount: /sys: unknown filesystem type 'sysfs'.
# mount -t tmpfs tmpfs /dev/shm -osize=100m,mode=1777
mount: /dev/shm: unknown filesystem type 'tmpfs'.
Click to expand...

I think you are close. If you want to mount it manually, I believe it should be:

Code: 
# mount -t linsysfs linsysfs /compat/debian/sys
# mount -t tmpfs tmpfs /compat/debian/dev/shm -osize=100m,mode=1777
 
hruodr said:
Indeed, dev from within chroot, but proc from host. Or is there a lindevfs?
Click to expand...
Yep, I think our native devfs is compatible enough to use directly.
Though the OP will likely want procfs too. This isn't native and so prefixed with lin*.

Code: 
# mount -t devfs devfs /compat/debian/dev
# mount -t linprocfs linprocfs /compat/debian/proc

There isn't much info on mounting it manually; mostly via fstab.

@OP, Make sure to mount /compat/debian/dev/shm *after* /compat/debian/dev.
 
Thanks everybody. Till now I collected:

Code: 
kldload linux64
sysctl compat.linux.emul_path=/compat/debian
mount -t devfs devfs /compat/debian/dev/
mount -t tmpfs tmpfs /compat/debian/dev/shm/
mount -t fdescfs -o linrdlnk null /compat/debian/dev/fd
mount -t linprocfs linprocfs /compat/debian/proc/
mount -t linsysfs linsysfs /compat/debian/sys/
chroot /compat/debian /bin/bash

Till now I cannot run xterm, opera segfaults. Outside chroot I get:

Code: 
# /compat/debian/bin/ls
ELF interpreter /lib64/ld-linux-x86-64.so.2 not found, error 2
Abort
 
Yeah that is a well know issue.
I am not at a freebsd box, so I cannot post absolute details, but the problem is that /lib64/ld-linux-x86-64.so.2 is an absolute link to some target and fails in linuxulator due to the missing prefix /compat/debian/.
Remove it from outside chroot and create a relative link for /compat/debian/lib64/ld-linux-x86-64.so.2 to ../<wherever it pointed> and the issue is gone.
 
I think you are meant to use the sysctl tunable for that issue:

From the handbook (with edits):

It is possible to debootstrap into /compat/linux, but it is discouraged to avoid collisions with files installed from FreeBSD ports and packages. Instead, derive the directory name from the distribution or version name, e.g., /compat/ubuntu. If the bootstrapped instance is intended to provide Linux shared libraries without having to explicitly use chroot or jails, one can point the kernel at it by updating the compat.linux.emul_path sysctl and adding a line like this to /etc/sysctl.conf:

compat.linux.emul_path="/compat/debian"
Click to expand...

So it is similar to an overlayfs / unionfs that if it can't find the lib in this directory (fake chroot), it will fall back to the / (root) which of course will fail because it either doesn't exist or is a FreeBSD binary that the linux emulated program can't use.

What is less clear is, since you are using a chroot, I am unsure if you need to set the sysctl to /compat/debian or just / because you are already using relative paths. I think it is the former due to the global nature of the sysctls, however you might want to have a play with both.
 
kpedersen said:
What is less clear is, since you are using a chroot, I am unsure if you need to set the sysctl to /compat/debian or just / because you are already using relative paths.
Click to expand...
As I wrote before, in chroot no problem, but outside.

I do not want to do jails, virtial machines and all the things the first contributors recomended. Just run linux binaries as
simple as possible.
 
elgrande said:
The command should be
Click to expand...
Issued from what directory? With ln -s I only use absolute paths.

And the command witll complain that /compat/debian/lib64/ld-linux-x86-64.so.2 exists.

Well, originaly
# ls -l /compat/debian/lib64/ld-linux-x86-64.so.2
lrwxr-xr-x 1 root wheel 32 Mar 17 21:37 /compat/debian/lib64/ld-linux-x86-64.so.2 -> /lib/x86_64-linux-gnu/ld-2.31.so
 
hruodr said:
Issued from what directory? With ln -s I only use absolute paths.

And the command witll complain that /compat/debian/lib64/ld-linux-x86-64.so.2 exists.
Click to expand...
Should not matter from which directory it is issued, ln -s creates relatively to where you create the link.

And you have to remove the broken link under /compat/debian/lib64/ld-linux-x86-64.so.2 first using rm /compat/debian/lib64/ld-linux-x86-64.so.2
 
I guess the original link looked for /lib/x86_64-linux-gnu/ld-2.31.so outside the chroot instead of /compat/debian/lib/x86_64-linux-gnu/ld-2.31.so
 
hruodr said:
I guess, outside chroot by following the link looked at /lib/x86_64-linux-gnu/ld-2.31.so and not /compat/debian/lib/x86_64-linux-gnu/ld-2.31.so

It seems, every link will be a problem.
Click to expand...

Haven't had a problem with other links yet.
No idea why though.
 
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