[arch-general] rootfs remains in ro at boot on fresh install with new December ISO
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? thank you very much! Olivier (A new Arch user and extremely happy to have found and tried your distribution!) ________________________________ CONFIDENTIALITY : This e-mail and any attachments are confidential and may be privileged. If you are not a named recipient, please notify the sender immediately and do not disclose the contents to another person, use it for any purpose or store or copy the information in any medium.
On Mon, Dec 03, 2012 at 05:00:48PM +0000, LANGLOIS Olivier PIS -EXT 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
You'll want to actually provide your /etc/fstab as well as the output of: systemctl status / Right after booting...
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.
'ro' is the default if neither 'rw' nor 'ro' are specified. If you want your root to be mounted rw initially, you need to do 2 things: 1) explicitly add 'rw' to your kernel cmdline 2) include the fsck hook in your initramfs Otherwise, it's left up to your /etc/fstab to ensure that it's remounted properly.
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?
Strange suspicion... Without seeing it, I suspect your /etc/fstab is at fault, simply because I've learned better than to trust anecdotal evidnce. d
Dave, Tom, Thank you very much for your explanations. With your help, I have become a little bit less clueless about systemd and Arch initramfs system. by typing systemctl status /, the reported status was ok/mounted with some green on the output. Nothing special to report about that. I wish that I could provide the exact text but I still suck at cut & pasting without a mouse! However I have fixed my problem and I think that I have stumbled into a systemd bug. Since I didn't want a tmpfs mounted in /tmp, I did follow directives from the Beginners guide: systemctl mask tmp.mount The result of that thing is: 1. rootfs is ro. 2. My disk partition for /tmp speficied in fstab isn't mounted. If I undo the change with: systemctl unmask tmp.mount everything comes back all right as expected. Not sure if it does that systematically for any fstab setup or I have been unlucky to have an extraordinary and unique fstab setup (I don't think so). Maybe someone could try to repeat the problem. If it is, then we have found a systemd bug, if not, I can share my fstab with interested parties. Greetings, Olivier
You'll want to actually provide your /etc/fstab as well as the output of:
systemctl status /
Right after booting...
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.
'ro' is the default if neither 'rw' nor 'ro' are specified. If you want your root to be mounted rw initially, you need to do 2 things:
1) explicitly add 'rw' to your kernel cmdline 2) include the fsck hook in your initramfs
Otherwise, it's left up to your /etc/fstab to ensure that it's remounted properly.
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?
Strange suspicion... Without seeing it, I suspect your /etc/fstab is at fault, simply because I've learned better than to trust anecdotal evidnce.
d
________________________________ CONFIDENTIALITY : This e-mail and any attachments are confidential and may be privileged. If you are not a named recipient, please notify the sender immediately and do not disclose the contents to another person, use it for any purpose or store or copy the information in any medium.
Hi Olivier,
On Tue, Dec 4, 2012 at 4:46 PM, LANGLOIS Olivier PIS -EXT
Since I didn't want a tmpfs mounted in /tmp, I did follow directives from the Beginners guide:
systemctl mask tmp.mount
The result of that thing is:
1. rootfs is ro.
2. My disk partition for /tmp speficied in fstab isn't mounted.
FWIW, if you have a /tmp entry in your fstab you don't need to mask tmp.mount (the fstab takes precedence). The only time you need to maks tmp.mount is if you don't want a partition mounted on /tmp at all.
Maybe someone could try to repeat the problem. If it is, then we have found a systemd bug, if not, I can share my fstab with interested parties.
Sounds like a bug, but haven't tried reproducing yet. Could you send your fstab for the record? Cheers, Tom
Tom, As requested, here is my fstab file. As you'll see, there is nothing fancy in it. /dev/sda1 isn't mounted as it is just my 2MB grub partition.
Since I didn't want a tmpfs mounted in /tmp, I did follow directives from the Beginners guide:
systemctl mask tmp.mount
The result of that thing is:
1. rootfs is ro.
2. My disk partition for /tmp speficied in fstab isn't mounted.
FWIW, if you have a /tmp entry in your fstab you don't need to mask tmp.mount (the fstab takes precedence). The only time you need to maks tmp.mount is if you don't want a partition mounted on /tmp at all.
Yep, I have discovered that as well during my experiments :-) ________________________________ CONFIDENTIALITY : This e-mail and any attachments are confidential and may be privileged. If you are not a named recipient, please notify the sender immediately and do not disclose the contents to another person, use it for any purpose or store or copy the information in any medium.
On Mon, Dec 3, 2012 at 6:00 PM, LANGLOIS Olivier PIS -EXT
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
participants (3)
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Dave Reisner
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LANGLOIS Olivier PIS -EXT
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Tom Gundersen