Alpine Linux - User contributions [en]

Create Alpine Linux PV DomU

2020-06-08T17:32:32Z

Davehill: Update menu.lst to grub.cfg

== Obtain a copy of Alpine Linux ==

To create an Alpine Linux paravirtualized (PV) DomU you will need an Alpine Linux iso.

Download the latest alpine-virt iso from https://alpinelinux.org/downloads/

In this example we will use {{path|/data/}} for our download and for our disk images.

==Mount the ISO image ==

Next, mount the iso so we can read the kernel and initramfs:

{{cmd | mount -t iso9660 -o loop /data/alpine-virt-{{AlpineLatest}}-x86_64.iso /media/cdrom }}

Now we have the kernel in {{path|/media/cdrom/boot/vmlinuz-virt}} and initramfs in {{path|/media/cdrom/boot/initramfs-virt}}.

Alternatively you can use {{path|uniso}} or {{path|p7zip}} to extract the content to a temp area.

== Create the disk image ==
Now we should create an empty file, that will be the hard drive of the DomU (in this example we are using a 3GB disk):

{{cmd | <nowiki>dd if=/dev/zero of=/data/a1.img bs=1M count=3000</nowiki>}}

Alternatively, if a LVM volume group (vg1 say) with free space is available on dom0, create a logical volume for alpine:

{{cmd | <nowiki>sudo lvcreate -n alpine -L 10g vg1</nowiki>}}

== Create a DomU config file that boots the ISO image ==
The next step is to create a basic DomU configuration file, so we can launch the pv guest iso (save it where you like, although the most common place is {{path|/etc/xen/}}).

{{cat | /etc/xen/a1.cfg | <nowiki># Alpine Linux PV DomU

# Kernel paths for install
kernel = "/media/cdrom/boot/vmlinuz-virt"
ramdisk = "/media/cdrom/boot/initramfs-virt"
extra="modules=loop,squashfs console=hvc0"

# Path to HDD and iso file
disk = [
'format=raw, vdev=xvda, access=w, target=/data/a1.img',
'format=raw, vdev=xvdc, access=r, devtype=cdrom, target=/data/alpine-virt-</nowiki>{{AlpineLatest}}<nowiki>-x86_64.iso'
]

# Network configuration
vif = ['bridge=br0']

# DomU settings
memory = 512
name = "alpine-a1"
vcpus = 1
maxvcpus = 1
</nowiki>}}

If using LVM, replace {{path|/data/a1.img}} with {{path|/dev/vg1/alpine}} in the disk specification.

== Install the guest ==
Now that we have all the necessary files, we can start the DomU to proceed with the install:

{{cmd|xl create -f /etc/xen/a1.cfg -c}}

Login into the system with user "root" and no password.

After configuring the basic system, you will be asked where would you like to install Alpine, choose xvda and sys.

This will create three partitions on your disk, xvda1 for /boot, xvda2 for swap and xvda3 for /

<pre>
Available disks are:
xvda (3.1 GB )
Which disk(s) would you like to use? (or '?' for help or 'none') [none] xvda
The following disk is selected:
xvda (3.1 GB )
How would you like to use it? ('sys', 'data' or '?' for help) [?] sys
WARNING: The following disk(s) will be erased:
xvda (3.1 GB )
WARNING: Erase the above disk(s) and continue? [y/N]: y
Initializing partitions on /dev/xvda...
Creating file systems...
Installing system on /dev/xvda3:

Installation is complete. Please reboot.

#
</pre>

When you reboot, the pv bootloader, pvgrub, will look to /boot/grub/grub.cfg for its menu, so create that file first.

Mount the boot partition and create a {{path|grub/grub.cfg}} file for pvgrub. (Note that grub.cfg is for pvgrub2 which replaced pvgrub1 and its menu.lst beginning in 2013.)

{{cmd |<nowiki>mount /dev/xvda1 /mnt
mkdir /mnt/grub</nowiki>}}

Install a basic text editor like nano or vim: 
{{cmd | apk add nano}}

If using nano, enter: 
{{cmd | nano /mnt/grub/grub.cfg}}

Then add the following to create a basic grub2 configuration file:
{{cat | /mnt/grub/grub.cfg |<nowiki>menuentry 'alpine-xen' {
set root=(xen/xvda,msdos1)
linux /boot/vmlinuz-virt root=/dev/xvda3 modules=ext4
initrd /boot/initramfs
}</nowiki>}}

Finally, Ctrl-S to save, Ctrl-X to exit nano.

Unmount and power off.
{{cmd |umount /mnt
poweroff}}

== Adjust the domU config file to boot from fresh install ==

In your Dom0, edit your DomU config file to boot with pvgrub.

{{cat | /etc/xen/a1.cfg |<nowiki># Alpine Linux PV DomU

kernel = "/usr/lib/xen/boot/pv-grub-x86_64.gz"

# Path to HDD and iso file
disk = [
'format=raw, vdev=xvda, access=w, target=/data/a1.img'
]

# Network configuration
vif = ['bridge=br0']

# DomU settings
memory = 512
name = "alpine-a1"
vcpus = 1
maxvcpus = 1
</nowiki>}}

The name and location of pvgrub in Dom0 is distribution-specific, so you may need to change the "kernel=" line, above.

For example, in Debian 10, it's {{path|'/usr/lib/grub-xen/grub-x86_64-xen.bin'}}

Remember to unmount the loopback iso image.
{{cmd | umount /media/cdrom}}

When you next boot, you will be presented with the grub boot menu, and your VM will boot.

== See also ==
* [https://www.linkedin.com/pulse/setting-up-alpine-linux-370-domu-vm-xenserver-72-ali-poursamadi Setting up Alpine Linux 3.7.0 as a domU VM on XenServer 7.2]

[[Category:Virtualization]]

Talk:Create Alpine Linux PV DomU

2020-06-06T16:53:34Z

Davehill:

This page was recommended by the Xen Beginners Guide as an example of a manual installation of a domU. It no longer works (at least on a Debian host) because it's based on legacy grub (grub1). I sorted out how to change it to work with grub2. Because I'm not a regular Alpine user, I thought it might be helpful to post proposed changes here in case there were comments before changing the page.

So, I propose changing the content to make it work with pvgrub2. The biggest change would be to swap out the instructions to create menu.lst with instructions to create grub.cfg as follows:

Before you reboot, mount the boot partition and create a {{path|grub/grub.cfg}} file for pvgrub: 
{{cmd | mount /dev/xvda1 /mnt
mkdir /mnt/grub}}
Install a basic text editor like nano or vim: 
{{cmd | apk add nano}}

If using nano, enter: 
{{cmd | nano /mnt/grub/grub.cfg}}

Then add the following to create a basic grub2 configuration file:
{{cat | /mnt/grub/grub.cfg |<nowiki>menuentry 'alpine-xen' {
set root=(xen/xvda,msdos1)
linux /boot/vmlinuz-virt root=/dev/xvda3 modules=ext4
initrd /boot/initramfs
}</nowiki>}}

Finally, Ctrl-S to save, Ctrl-X to exit nano.

I would add/change a few other small things: a bit more on pvgrub2, instructions to use LVM if that's set up in the host and a few more details around the initial installation process, etc.

Comments welcome.

-- [[User:Davehill|Davehill]] ([[User talk:Davehill|talk]]) 16:53, 6 June 2020 (UTC)

I had problems booting a 32bit Alpine domU on a OracleVM 2.2.2 (64bit) host - most probably since the Alpine kernel uses PVops. 

The domU kernel failed to load with the following error: 

:Error: (2, 'Invalid kernel', 'elf_xen_note_check: ERROR: Will only load images built for the generic loader or Linux images')

Solution is to make sure you have a 64bit ISO.

Changes:
I had to ln -s /media/cdrom to /media/xvdc or setup-alpine would not find some information.

The root fs would end up in readonly mount even when it shouldn't. Reason is that the barrier test during mount fails, if some of the underlying layers do not pass barriers (i.e. older LVM/DM in dom0). You have to change the /etc/fstab of the VM *and* run tune2fs -o nobarrier on the filesystem do disable barriers (or update the dom0).
The "mounting root filesystem rw" init script prints out OK during all that, I'll be opening a bug about it. Right now the bugtracker does not send out confirmation emails.

One more thing: didnt the local Xen god hack pygrub to be able to boot alpine directly?
This howto still assumes we need to save kernel somewhere, maybe we can instead pass them as arguments at first build. More complex but also more powerful.

Talk:Create Alpine Linux PV DomU

2020-06-03T15:47:20Z

Davehill:

This page was recommended by the Xen Beginners Guide as an example of a manual installation of a domU. It no longer works (at least on a Debian host) because it's based on legacy grub (grub1). I sorted out how to change it to work with grub2. Because I'm not a regular Alpine user, I thought it might be helpful to post proposed changes here in case there were comments before changing the page.

So, I propose changing the content to make it work with pvgrub2. The biggest change would be to swap out the instructions to create menu.lst with instructions to create grub.cfg as follows:

Before you reboot, mount the boot partition and create a {{path|grub/grub.cfg}} file for pvgrub: 
{{cmd | mount /dev/xvda1 /mnt
mkdir /mnt/grub}}
Install a basic text editor like nano or vim: 
{{cmd | apk add nano}}

If using nano, enter: 
{{cmd | nano /mnt/grub/grub.cfg}}

Then add the following to create a basic grub2 configuration file:
{{cat | /mnt/grub/grub.cfg |<nowiki>menuentry 'alpine-xen' {
set root=(xen/xvda,msdos1)
linux /boot/vmlinuz-virt root=/dev/xvda3 modules=ext4
initrd /boot/initramfs
}</nowiki>}}

Finally, Ctrl-S to save, Ctrl-X to exit nano.

I would add/change a few other small things: a bit more on pvgrub2, instructions to use LVM if that's set up in the host and a few more details around the initial installation process, etc.

Comments welcome.

I had problems booting a 32bit Alpine domU on a OracleVM 2.2.2 (64bit) host - most probably since the Alpine kernel uses PVops. 

The domU kernel failed to load with the following error: 

:Error: (2, 'Invalid kernel', 'elf_xen_note_check: ERROR: Will only load images built for the generic loader or Linux images')

Solution is to make sure you have a 64bit ISO.

Changes:
I had to ln -s /media/cdrom to /media/xvdc or setup-alpine would not find some information.

The root fs would end up in readonly mount even when it shouldn't. Reason is that the barrier test during mount fails, if some of the underlying layers do not pass barriers (i.e. older LVM/DM in dom0). You have to change the /etc/fstab of the VM *and* run tune2fs -o nobarrier on the filesystem do disable barriers (or update the dom0).
The "mounting root filesystem rw" init script prints out OK during all that, I'll be opening a bug about it. Right now the bugtracker does not send out confirmation emails.

One more thing: didnt the local Xen god hack pygrub to be able to boot alpine directly?
This howto still assumes we need to save kernel somewhere, maybe we can instead pass them as arguments at first build. More complex but also more powerful.

Talk:Create Alpine Linux PV DomU

2020-06-03T15:37:14Z

Davehill:

This was recommended as a manual installation by the Xen Beginners Guide. It didn't work because it seems to be based on GRUB1. Because I'm not a regular Alpine user, I thought it might be helpful to post proposed changes here first.

So, I propose changing the content to make it work with pvgrub2. The biggest change would be to swap out the instructions to create menu.lst with instructions to create grub.cfg as follows:

Before you reboot, mount the boot partition and create a {{path|grub/grub.cfg}} file for pvgrub: 
{{cmd | mount /dev/xvda1 /mnt
mkdir /mnt/grub}}
Install a basic text editor like nano or vim: 
{{cmd | apk add nano}}

If using nano, enter: 
{{cmd | nano /mnt/grub/grub.cfg}}

Then add the following to create a basic grub2 configuration file:
{{cat | /mnt/grub/grub.cfg |<nowiki>menuentry 'alpine-xen' {
set root=(xen/xvda,msdos1)
linux /boot/vmlinuz-virt root=/dev/xvda3 modules=ext4
initrd /boot/initramfs
}</nowiki>}}

Finally, Ctrl-S to save, Ctrl-X to exit nano.

I would add/change a few other small things: a bit more on pvgrub2, instructions to use LVM if that's set up in the host and a few more details around the initial installation process, etc.

Comments welcome.

I had problems booting a 32bit Alpine domU on a OracleVM 2.2.2 (64bit) host - most probably since the Alpine kernel uses PVops. 

The domU kernel failed to load with the following error: 

:Error: (2, 'Invalid kernel', 'elf_xen_note_check: ERROR: Will only load images built for the generic loader or Linux images')

Solution is to make sure you have a 64bit ISO.

Changes:
I had to ln -s /media/cdrom to /media/xvdc or setup-alpine would not find some information.

The root fs would end up in readonly mount even when it shouldn't. Reason is that the barrier test during mount fails, if some of the underlying layers do not pass barriers (i.e. older LVM/DM in dom0). You have to change the /etc/fstab of the VM *and* run tune2fs -o nobarrier on the filesystem do disable barriers (or update the dom0).
The "mounting root filesystem rw" init script prints out OK during all that, I'll be opening a bug about it. Right now the bugtracker does not send out confirmation emails.

One more thing: didnt the local Xen god hack pygrub to be able to boot alpine directly?
This howto still assumes we need to save kernel somewhere, maybe we can instead pass them as arguments at first build. More complex but also more powerful.

Talk:Create Alpine Linux PV DomU

2020-06-03T15:16:03Z

Davehill:

This was recommended as a manual installation by the Xen Beginners Guide. It didn't work because it seems to be based on GRUB1. Because I'm not a regular Alpine user, I thought it might be helpful to post proposed changes here first.

So, I propose changing the content to make it work with pvgrub2. The biggest change would be to swap out the instructions to create menu.lst with instructions to create grub.cfg as follows:

Before you reboot, mount the boot partition and create a grub/grub.cfg file for pvgrub: 
<code>mount /dev/xvda1 /mnt</code>
<code>mkdir /mnt/grub</code>
Install a basic text editor like nano or vim: 
<code>apk add nano</code>

If using nano, enter: 
<code>nano /mnt/grub/grub.cfg</code>

Then add the following to create a basic grub2 file:
menuentry 'alpine-xen' {
set root=(xen/xvda,msdos1)
linux /boot/vmlinuz-virt root=/dev/xvda3 modules=ext4
initrd /boot/initramfs
}
Finally, Ctrl-S to save, Ctrl-X to exit nano.

I would add/change a few other small things: a bit more on pvgrub2, instructions to use LVM if that's set up in the host and a few more details around the initial installation process, etc.

Comments welcome.

I had problems booting a 32bit Alpine domU on a OracleVM 2.2.2 (64bit) host - most probably since the Alpine kernel uses PVops. 

The domU kernel failed to load with the following error: 

:Error: (2, 'Invalid kernel', 'elf_xen_note_check: ERROR: Will only load images built for the generic loader or Linux images')

Solution is to make sure you have a 64bit ISO.

Changes:
I had to ln -s /media/cdrom to /media/xvdc or setup-alpine would not find some information.

The root fs would end up in readonly mount even when it shouldn't. Reason is that the barrier test during mount fails, if some of the underlying layers do not pass barriers (i.e. older LVM/DM in dom0). You have to change the /etc/fstab of the VM *and* run tune2fs -o nobarrier on the filesystem do disable barriers (or update the dom0).
The "mounting root filesystem rw" init script prints out OK during all that, I'll be opening a bug about it. Right now the bugtracker does not send out confirmation emails.

One more thing: didnt the local Xen god hack pygrub to be able to boot alpine directly?
This howto still assumes we need to save kernel somewhere, maybe we can instead pass them as arguments at first build. More complex but also more powerful.

Talk:Create Alpine Linux PV DomU

2020-06-03T04:24:11Z

Davehill: Replace menu.lst with grub.cfg

This was recommended as a manual installation by the Xen Beginners Guide. It didn't work because it seems to be based on GRUB1. Because I'm not a regular Alpine user, I thought it might be helpful to post proposed changes here first.

So, I propose changing the content to make it work with pvgrub2. The biggest change would be to swap out the instructions to create menu.lst with instructions to create grub.cfg as follows:

Before you reboot, mount the boot partition and create a grub/grub.cfg file for pvgrub:

mount /dev/xvda1 /mnt

mkdir /mnt/grub

If vim or emacs are good with you, create the file below as /boot/grub/grub.cfg. If not, first install nano with:

apk add nano

If using vim or apt, you presumably already know what your doing.

If using nano, the grub.cfg file should at least contain a basic grub2 file. Enter:

nano /mnt/grub/grub.cfg

then add the following to the new file:

menuentry 'alpine-xen' {
set root=(xen/xvda,msdos1)
linux /boot/vmlinuz-virt root=/dev/xvda3 modules=ext4
initrd /boot/initramfs
}

Ctrl-S to save, Ctrl-X to exit.

(and then carry on with the instructions).

I would add/change a few other small things: a bit more on pvgrub2, instructions to use LVM if that's set up in the host and a few more details around the initial installation process, etc.

Comments welcome.

I had problems booting a 32bit Alpine domU on a OracleVM 2.2.2 (64bit) host - most probably since the Alpine kernel uses PVops. 

The domU kernel failed to load with the following error: 

:Error: (2, 'Invalid kernel', 'elf_xen_note_check: ERROR: Will only load images built for the generic loader or Linux images')

Solution is to make sure you have a 64bit ISO.

Changes:
I had to ln -s /media/cdrom to /media/xvdc or setup-alpine would not find some information.

The root fs would end up in readonly mount even when it shouldn't. Reason is that the barrier test during mount fails, if some of the underlying layers do not pass barriers (i.e. older LVM/DM in dom0). You have to change the /etc/fstab of the VM *and* run tune2fs -o nobarrier on the filesystem do disable barriers (or update the dom0).
The "mounting root filesystem rw" init script prints out OK during all that, I'll be opening a bug about it. Right now the bugtracker does not send out confirmation emails.

One more thing: didnt the local Xen god hack pygrub to be able to boot alpine directly?
This howto still assumes we need to save kernel somewhere, maybe we can instead pass them as arguments at first build. More complex but also more powerful.