[arch-general] rootfs remains in ro at boot on fresh install with new December ISO

[Tom Gundersen]

On Mon, Dec 3, 2012 at 6:00 PM, LANGLOIS Olivier PIS -EXT
<olivier.pis.langlois at transport.alstom.com> wrote:
> Hi,
>
> I hope it is not caused by the shortcut that I have taken to update my usb install key from november iso to december iso as described in the other thread.
>
> The first symptom that I have observed is that dhcpcd isn't able to update /etc/resolv.conf
>
> I am going to provide as much relevant info so you can tell me what to look for
>
> 1. Installed from december iso on newly created GPT ext4 partitions
> 2. Bootloader GRUB2
> 3. Did a systemctl mask tmpfs as I am mounting a disk partition on /tmp from fstab
> 4. Double checked 2-3 times that all my mounts are rw in fstab
> 5. Once logged, I have no problem doing "mount -o remount,rw /"
> 6. I have removed the ro kernel parameter option in grub.cfg (BTW, why is this used at all? I'm a little bit ignorant about Linux booting good practices). By doing so rootfs still remains ro.
>
> I am suspecting either systemd or the content of the initramfs. Until now, those are still black boxes to me. What should I look at to resolve my rootfs ro problem?

There are two ways for / to be mounted rw: either by the initramfs by
specifying "rw" on the kernelcommandline. Or by systemd remounting it
based on your fstab, for that to happen you need to have an entry in
fstab for your rootfs.

Traditionally the second option was necessary to make it possible to
fsck your rootfs. However, now that the initramfs has the fsck hook,
this is no longer necessary, and you can just mount it 'rw' from the
beginning, and skip remounting it later on.

Cheers,

Tom