Re: [gentoo-user] What to put in chroot mtab

["Canek Peláez Valdés" <caneko@gmail.com>]

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On Aug 1, 2014 3:46 PM, "J. Roeleveld" <joost@antarean.org> wrote:
>
> On 1 August 2014 15:28:01 CEST, Dale <rdalek1967@gmail.com> wrote:
> >Peter Humphrey wrote:
> >> On Friday 01 August 2014 14:07:08 I wrote:
> >>
> >>> I run a couple of chroots on this box to build packages for other
> >boxes on
> >>> the LAN. So far, I haven't worked out what I should populate
> >/etc/mtab with
> >>> in each chroot. Is it enough to "grep ext4 /etc/mtab >
> >>> /mnt/chroot/etc/mtab"? That catches all the physical partitions, but
> >I
> >>> imagine I need to add some /proc, /sys and /dev entries as well, but
> >is
> >>> there a simple formula for doing this?
> >> I meant to add that one chroot is 32-bit and the other is 64. The
> >host is an
> >> i5 running openrc.
> >>
> >
> >It has been a good while since I used this.  So, make sure it makes
> >sense to you before trying this.  This may not work if something has
> >changed in the past several years.  Use with caution if at all.
> >
> >This is a little script, if you want to call it that, that I used to do
> >mine.  It also lists the command to use to do a 32 bit chroot from a 64
> >bit rig.  Here it is:
> >
> >root@fireball / # cat /root/xx.chroot-mount-32bit
> >
> >
> >mount -o bind /dev /mnt/gentoo32/dev
> >mount -o bind /dev/pts /mnt/gentoo32/dev/pts
> >mount -o bind /dev/shm /mnt/gentoo32/dev/shm
> >mount -o bind /proc /mnt/gentoo32/proc
> >mount -o bind /proc/bus/usb /mnt/gentoo32/proc/bus/usb
> >mount -o bind /sys /mnt/gentoo32/sys
> >mkdir -p /mnt/gentoo32/usr/portage/
> >mount -o bind /usr/portage /mnt/gentoo32/usr/portage/
> >
> >
> >echo " mounting finished"
> >
> >echo "run linux32 chroot /mnt/gentoo32 /bin/bash next"
> >root@fireball / #
> >
> >
> >You may have different mount points at the very least so edit to match
> >what you have.  Again, things could have changed and that no longer
> >will
> >work.  It may not be a bad idea to let someone who has done this more
> >recently to give a thumbs up to that.
> >
> >That last command should be:
> >
> >linux32 chroot /mnt/gentoo32 /bin/bash
> >
> >Dale
> >
> >:-)  :-)
>
> That script is too long :)
>
> cd /mnt/gentoo
> mount -o rbind /dev dev
> mount -o rbind /sys sys
> mount -o rbind /proc proc
> cp -L /etc/resolv.conf etc/resolv.conf
> cd ..
> chroot gentoo /bin/bash
>
> To undo:
> cd /mnt/gentoo
> umount -l proc sys dev

That's still too long :)

With systemd-nspawn, you only do:

systemd-nspawn -D /mnt/gentoo

Systemd takes care of /dev, /sys, etc. If the container has systemd
installed, you can do

systemd-nspawn -bD /mnt/gentoo

and the services inside the container will be started like in a regular
boot (you'll need to set the root password for the container).

Also, if you want to share the /usr/portage directory between host and
container, you only need to

systemd-nspawn --bind=/usr/portage -bD /mnt/gentoo

Regards.
--
Canek

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