Bootloaders: Difference between revisions

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By default Alpine uses Syslinux as bootloader.
 
This page shows the basic steps you need to perform, if you for any reason want to switch bootloaders or apply some manual configuration.
This page shows the basic steps you need to perform, if you for any reason want to switch bootloaders or apply some manual configuration.


* <code>[[#Syslinux|Syslinux]]</code> is the default light-weight bootloader used in Alpine.<br>
* <code>[[#rEFInd|rEFInd]]</code> is an easy to use EFI boot menu that allows booting different operating systems.<br>
* <code>[[#GRUB|GRUB]]</code> is a standard linux boot loader.<br>
* <code>[[#EFI_Boot_Stub|EFI Boot Stub]]</code> allows booting linux directly from a motherboard supporting UEFI or another bootloader.<br>
* Gummiboot can be used for [[UEFI Secure Boot]].


= Installing Syslinux =
= rEFInd =


If you want to switch from another bootloader back to Syslinux, or if you for some reason want to install Syslinux manually, the following steps are required.
For (U)EFI systems, the {{pkg|refind}} package can provide a graphical EFI boot menu that allows to boot operating systems that are found on the available partitions.


Install the <code>syslinux</code> package:
If <code>refind</code> is not yet available in the used alpine release, it may be installed in another dual/multi-booted linux distribution.


<pre>apk add syslinux</pre>
For example, with a Debian based distribution, it can be installed to the EFI partition like this:
{{cmd|<nowiki># apt install refind            # installs the debian package
# refind-install --alldrivers    # installs refind to the EFI partition
</nowiki>}}


If you're using GPT partitions, install the GPT MBR onto the drive you want to install the bootloader on (in this case <code>/dev/sda</code>):
(The <code>--alldrivers</code> option includes all filesystem drivers instead of only the one needed to load the currently running kernel, to allow finding and booting operating systems from more partitions.)


<pre>dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/gptmbr.bin of=/dev/sda</pre>
And a first (default) boot menu line needs to be configured with Alpine's default boot parameters. Assuming the bootable partition is mounted at {{path|/media/sdXY}} it can be done like this (at time of writing):
{{cmd|<nowiki># echo '"Alpine" "modules=loop,squashfs,sd-mod,usb-storage quiet initrd=\boot\intel-ucode.img initrd=\boot\amd-ucode.img initrd=\boot\initramfs-lts"' > /media/sdXY/boot/refind_linux.conf</nowiki>}}


Or if you're using DOS partitions, install the DOS MBR instead:
{{Note|At the time of writing, it was still needed to use backslashes in the .conf file.<br>
The path in the config file needs to be relative to the partition that the kernel resides on. If {{path|/boot}} resides on its own separate partition, then <code>\boot</code> needs to be removed from the paths.}}


<pre>dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/mbr.bin of=/dev/sda</pre>
= Syslinux =


<!-- See also: http://www.syslinux.org/wiki/index.php?title=Mbr -->
If you want to switch from another bootloader back to Syslinux, or if you for some reason want to install Syslinux manually, the following steps are required.


Next install the required Syslinux binaries. Despite being called <code>extlinux</code>, Syslinux supports booting from FAT12/16/32, NTFS, ext2/3/4, Btrfs, XFS, and UFS/FFS filesystems.
Install the {{pkg|syslinux}} package:


<pre>extlinux --install /boot</pre>
{{cmd|# apk add syslinux}}


The configuration file is located in <code>/boot/extlinux.conf</code>.
If you're using GPT partitions, install the GPT MBR onto the drive you want to install the bootloader on (in this case {{path|/dev/sda}}):
Alpine ships with a script called <code>update-extlinux</code> which automatically (re)generates this file, for example on updates to Syslinux.
The settings for this script can be found in <code>/etc/update-extlinux.conf</code>, including the option to disable automatic overwriting of <code>/boot/extlinux.conf</code>.
You can also place additional menu entries in the <code>/etc/update-extlinux.d/</code> directory, e.g. for dual booting.


{{cmd|<nowiki># dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/gptmbr.bin of=/dev/sda</nowiki>}}


== EFI ==
Or if you're using DOS partitions, install the DOS MBR instead:


{{Todo|Work in progress. This should at least get you started.}}
{{cmd|<nowiki># dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/mbr.bin of=/dev/sda</nowiki>}}


Assuming <code>/mnt</code> is a FAT32 partition of type EF00 and <code>/boot</code> belongs to the rootfs created after running <code>setup-disk</code>:
<!-- See also: http://www.syslinux.org/wiki/index.php?title=Mbr -->


<pre>
Next install the required Syslinux binaries. Despite being called <code>extlinux</code>, Syslinux supports booting from FAT12/16/32, NTFS, ext2/3/4, [[Btrfs|btrfs]], XFS, and UFS/FFS filesystems.
mkdir -p /mnt/EFI/syslinux
cp /usr/share/syslinux/efi64/* /mnt/EFI/syslinux/
cp /boot/extlinux.conf /mnt/EFI/syslinux/syslinux.cfg
cp /boot/vmlinuz* /mnt/
cp /boot/initramfs* /mnt/
</pre>


You may need to modify <code>/mnt/EFI/syslinux/syslinux.cfg</code> to change the paths to absolute paths (just add a / in front of the vmlinuz/initramfs entries),
{{cmd|# extlinux --install /boot}}
or copy the files to <code>/mnt/EFI/syslinux</code> instead (XXX: untested).


= GRUB =
The configuration file is located in {{path|/boot/extlinux.conf}}.
Alpine ships with a script called <code>update-extlinux</code> which automatically (re)generates this file, for example on updates to Syslinux.
The settings for this script can be found in {{path|/etc/update-extlinux.conf}}, including the option to disable automatic overwriting of {{path|/boot/extlinux.conf}}.
You can also place additional menu entries in the {{path|/etc/update-extlinux.d/}} directory, e.g. for dual booting.


To install GRUB in BIOS mode, (optionally) remove the Syslinux package and install the required GRUB packages:


<pre>apk del syslinux
=== EFI ===
apk add grub grub-bios</pre>


For EFI, install Grub's EFI package instead. Note that <code>/boot</code> has to be an EFI compatible filesystem like FAT32.
{{Todo|Work in progress. This should at least get you started.}}


<pre>apk add grub-efi</pre>
Assuming {{path|/mnt}} is a FAT32 partition of type EF00 and {{path|/boot}} belongs to the rootfs created after running <code>setup-disk</code>:


Next install the MBR and GRUB binaries to disk for BIOS mode:
{{cmd|<nowiki># mkdir -p /mnt/EFI/syslinux
 
# cp /usr/share/syslinux/efi64/* /mnt/EFI/syslinux/
<pre>grub-install /dev/vda</pre>
# cp /boot/extlinux.conf /mnt/EFI/syslinux/syslinux.cfg
 
# cp /boot/vmlinuz* /mnt/EFI/syslinux/
For EFI mode:
# cp /boot/initramfs* /mnt/EFI/syslinux/
 
</nowiki>}}
<pre>grub-install --target=x86_64-efi --efi-directory=/boot</pre>
 
GRUB ships with an automatic config generator, including some automatic detection of other operating systems installed on the device:
 
<pre>grub-mkconfig -o /boot/grub/grub.cfg</pre>
 
This script can be configured via the <code>/etc/default/grub</code> file.
See [https://www.gnu.org/software/grub/manual/html_node/Simple-configuration.html] for a list of available options.


= systemd-boot=
You may need to modify {{path|/mnt/EFI/syslinux/syslinux.cfg}} to change the paths to absolute paths (just add a / in front of the vmlinuz/initramfs entries),
or copy the files to {{path|/mnt/EFI/syslinux}} instead (XXX: untested).


{{Todo|Work in progress. This is very short and doesn't cover a lot of the options.}}
At the end, the file {{path|/mnt/EFI/syslinux/syslinux.cfg}} should look like this:
{{cat|/mnt/EFI/syslinux/syslinux.cfg|<nowiki>...
DEFAULT menu.c32
PROMPT 0
MENU TITLE Alpine/Linux Boot Menu
MENU HIDDEN
MENU AUTOBOOT Alpine will be booted automatically in # seconds
TIMEOUT 10
LABEL lts
  MENU DEFAULT
  MENU LABEL Linux lts
  LINUX /vmlinuz-lts
  INITRD /initrd-lts
  APPEND root=/dev/sda3 modules=sd-load,usb-storage,ext4 quiet
</nowiki>}}


Systemd-boot is the simple EFI bootloader part of the systemd project. It is also available in the Alpine Linux testing repository as a standalone component.
And finally, add syslinux to EFI boot menu (assuming {{path|/dev/sda}} is your hard drive)
{{cmd|<nowiki># apk add efibootmgr
# efibootmgr -c -d /dev/sda -p 1 -l \\EFI\\syslinux\\syslinux.efi -L "ALPINE-SYSLINUX"
</nowiki>}}


== Installing ==
You can now verify that the boot entry has been added
 
To install the systemd-boot, enable the testing repository, and install the <code>systemd-boot</code> package. Then make sure the boot and EFI partitions are mounted as read-write and install the bootloader with <code>bootctl</code>.


'''efibootmgr'''
<pre>
<pre>
# apk add systemd-boot
BootCurrent: 0001
# bootctl install
Timeout: 0 seconds
BootOrder: 0001,0000,0002,...
Boot001* ALPINE-SYSLINUX HD(1,GPT,xxxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)/FILE(\EFI\syslinux\syslinux.efi)
</pre>
</pre>


The <code>bootctl</code> binary also has support for checking if the bootloader is installed.
= GRUB =


<pre>
To install GRUB in BIOS mode, (optionally) remove the Syslinux package and install the required GRUB packages:
# bootctl is-installed
yes
</pre>


== Configuring ==
{{cmd|<nowiki># apk del syslinux
# apk add grub grub-bios
</nowiki>}}


Example configuration files for alpine are available on <code>/usr/share/systemd/bootctl</code> as <code>loader.conf</code> and <code>alpine.conf</code>.
For EFI, install GRUB's EFI package instead. Note that {{path|/boot}} has to be an EFI compatible filesystem like FAT32.


The bootloader (not the boot entries) can be configured via the [https://www.freedesktop.org/software/systemd/man/loader.conf.html# loader.conf] file, an example is available in <code>/usr/share/systemd/bootctl/loader.conf</code>.
{{cmd|# apk add grub-efi efibootmgr}}


<pre>
Next install the MBR and GRUB binaries to disk for BIOS mode:
# cp /usr/share/systemd/bootctl/loader.conf /boot/loader
# vi /boot/loader/loader.conf
</pre>


systemd-boot makes use of configuration files in <code>/boot/loader/entries</code> to list entries for different OSes it can boot into. An example file for Alpine Linux is present on <code>/usr/share/systemd/bootctl/alpine.conf</code>.
{{cmd|# grub-install /dev/vda}}


<pre>
For EFI mode:
# cp /usr/share/systemd/bootctl/alpine.conf /boot/loader/entries
# vi /boot/loader/entries/alpine.conf
</pre>


The example file has a skeleton structure that requires minimal modifications to make them work. You need to modify the example file to fit your oeprating system, among them:
{{cmd|<nowiki># grub-install --target=x86_64-efi --efi-directory=/boot</nowiki>}}


* Replace root=UUID=XXXX with the UUID of the root partition.
then add this line to {{path|/etc/default/grub}}:
* Replace rootfstype with the filesystem used for the root filesystem.
{{cat|/etc/default/grub|<nowiki># GRUB_CMDLINE_LINUX_DEFAULT="quiet rootfstype=ext4 modules=sd-mod,usb-storage,ext4"</nowiki>}}
* Add boot options required/recommended for booting your operating system (E.g: cryptdm=, cryptroot=, modules=, etc).
* (If you don't use the default linux-lts kernel) Replace vmlinuz-lts and initramfs-lts with the ones that are used.
* (If you use an Intel CPU and need Intel microcode) add <code>initrd /intel-ucode.img</code> before the initrd call for the initramfs 


All the options available are documented in the [https://systemd.io/BOOT_LOADER_SPECIFICATION/ systemd boot loader specification] under Technical Details.
GRUB ships with an automatic config generator, including some automatic detection of other operating systems installed on the device:


=== Unified Kernel Images ===
{{cmd|# grub-mkconfig -o /boot/grub/grub.cfg}}


Systemd-boot also accepts unified kernel images, as outlined in their [https://systemd.io/BOOT_LOADER_SPECIFICATION/#type-2-efi-unified-kernel-images document]. They are a combination of various pieces that are usually separate when normally booting, like the kernel, the initramfs and the kernel commandline.
This script can be configured via the {{path|/etc/default/grub}} file.
See [https://www.gnu.org/software/grub/manual/html_node/Simple-configuration.html] for a list of available options.


To generate a unified kernel image the <code>objcopy</code> binary can be used:
= EFI Boot Stub =


<pre>
To boot directly from your motherboard's UEFI boot menu, a boot entry needs
# objcopy \
to be created with either a UEFI shell or ''efibootmgr''.
--add-section .osrel="/etc/os-release" --change-section-vma .osrel=0x20000 \
--add-section .cmdline="/proc/cmdline" --change-section-vma .cmdline=0x30000 \
--add-section .linux="$(bootctl -x)/vmlinuz-lts" --change-section-vma .linux=0x40000 \
--add-section .initrd="$(bootctl -x)/initramfs-lts" --change-section-vma .initrd=0x3000000 \
/usr/lib/systemd/boot/efi/linuxx64.efi.stub $(bootctl -p)/EFI/Linux/linux.efi
</pre>


The above can be signed, with the bootloader, for use in Secure Boot.
== efibootmgr ==


Users that also require CPU microcode (like intel-ucode) can also include it by concatenating the CPU microcode .img file before the normal initramfs into a single .img file.
Install efibootmgr:
{{cmd|# apk add efibootmgr}}


<pre>
Create a boot entry. It's recommended to do this in a script, as efibootmgr
# cat $(bootctl -x)/cpu_microcode.img $(bootctl -x)/initramfs-lts > /tmp/initramfs-lts
does not allow editing entries.
</pre>


Then use that in the .initrd section of the <code>objcopy</code> call.
{{cat|add-bootentry|<nowiki>#!/bin/sh


== Listing Information and Status ==
params="root=/dev/sdXZ rootfstype=ext4 rw \
  initrd=\intel-ucode.img \
  initrd=\initramfs-lts"


<code>bootctl</code> can also list the entries available, which one is default and a wealth of information from them. (Example from Alpine Linux developer Leo, which inculdes an entry and a Unified Kernel Image)
efibootmgr --create --label "Alpine Linux" \
  --disk /dev/sdX --part Y \
  --loader /vmlinuz-lts \
  --unicode "${params}" \
  --verbose
</nowiki>}}


<pre>
Where {{path|/dev/sdXY}} contains the EFI partition and {{path|/dev/sdXZ}} contains the root partition. If you are using {{Pkg|linux-edge}}, replace <code>lts</code> with <code>edge</code> in the script
# bootctl list
Boot Loader Entries:
        title: Alpine Linux
          id: alpine
      source: /boot/loader/entries/alpine.conf
        linux: /vmlinuz-lts
      initrd: /intel-ucode.img
              /initramfs-lts
      options: root=UUID=1437f4dd-7efd-4a4e-8fac-797b548076d1 cryptdm=pool cryptroot=/dev/sda2 modules=ext4,xfs rootfstype=ext4 psi=1 quiet


        title: Alpine Linux edge (default)
{{Note|
          id: alpine-3.12_alpha20200122
The kernel contains the [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/init/do_mounts.c#n254 exhaustive list] of ways to specify the block device. For a more robust boot entry, it is recommended to use a persistent name such as the PARTUUID.
      source: /boot/EFI/Linux/linux.efi
}}
        linux: EFI/Linux/linux.efi
      options: initrd=\intel-ucode.img initrd=\initramfs-lts root=UUID=1437f4dd-7efd-4a4e-8fac-797b548076d1 cryptdm=pool cryptroot=/dev/sda2 modules=ext4,xfs rootfstype=ext4 psi=1 quiet


        title: Reboot Into Firmware Interface
Optionally, set the newly created entry as the default:
          id: auto-reboot-to-firmware-setup
      source: /sys/firmware/efi/efivars/LoaderEntries-4a67b082-0a4c-41cf-b6c7-440b29bb8c4f
</pre>


And it can also list general status of the system, including information on the current bootloader, the system firmware and options (like if Secure Boot is enabled).
{{cmd|# efibootmgr -n XXXX}}


<pre>
Where <code>XXXX</code> is the boot number of the new entry.
# bootctl status
System:
    Firmware: UEFI 2.40 (American Megatrends 5.11)
  Secure Boot: disabled
  Setup Mode: user
 
Current Boot Loader:
      Product: systemd-boot 243
    Features: ✓ Boot counting
              ✓ Menu timeout control
              ✓ One-shot menu timeout control
              ✓ Default entry control
              ✓ One-shot entry control
              ✓ Support for XBOOTLDR partition
              ✓ Support for passing random seed to OS
          ESP: /dev/disk/by-partuuid/00e7649e-bf1f-481b-87cd-7228af8c118f
        File: └─/EFI/systemd/systemd-bootx64.efi
 
Random Seed:
Passed to OS: yes
System Token: set
      Exists: yes
 
Available Boot Loaders on ESP:
          ESP: /boot (/dev/disk/by-partuuid/00e7649e-bf1f-481b-87cd-7228af8c118f)
        File: └─/EFI/systemd/systemd-bootx64.efi (systemd-boot 243)
        File: └─/EFI/BOOT/BOOTX64.EFI (systemd-boot 243)
 
Boot Loaders Listed in EFI Variables:
        Title: Linux Boot Manager
          ID: 0x0007
      Status: active, boot-order
    Partition: /dev/disk/by-partuuid/00e7649e-bf1f-481b-87cd-7228af8c118f
        File: └─/EFI/systemd/systemd-bootx64.efi
 
        Title: Alpine
          ID: 0x0006
      Status: active, boot-order
    Partition: /dev/disk/by-partuuid/00e7649e-bf1f-481b-87cd-7228af8c118f
        File: └─/EFI/EFI/alpine/grubx64.efi
 
        Title: Windows Boot Manager
          ID: 0x0000
      Status: active
    Partition: /dev/disk/by-partuuid/fd36bbae-be4f-409a-b1ce-14771e091067
        File: └─/EFI/Microsoft/Boot/bootmgfw.efi
 
Boot Loader Entries:
        $BOOT: /boot (/dev/disk/by-partuuid/00e7649e-bf1f-481b-87cd-7228af8c118f)


Default Boot Loader Entry:
{{Note|
        title: Alpine Linux
The loader and initrd file arguments are relative to the EFI partition. In a default installation, alpine places these files in {{path|/boot/}}, while EFI is mounted to {{path|/boot/efi/}}. You can either update fstab to mount EFI at {{path|/boot/}}, or manually copy them to {{path|/boot/efi/}}.                                                                                          }}
          id: alpine
      source: /boot/loader/entries/alpine.conf
        linux: /vmlinuz-lts
      initrd: /intel-ucode.img
              /initramfs-lts
      options: root=UUID=1437f4dd-7efd-4a4e-8fac-797b548076d1 cryptdm=pool cryptroot=/dev/sda2 modules=ext4,xfs rootfstype=ext4 psi=1 quiet
</pre>


== Updating ==
= Using a UKI (UEFI only) =


When the <code>systemd-boot</code> package is updated the bootloader installed needs to be updated as well:
It is possible to boot directly into a '''Unified Kernel Image''' (UKI). A UKI is a single file which contains the initfs, kernel and cmdline. While this is typically done in order to enable [https://en.wikipedia.org/wiki/UEFI SecureBoot], it is perfectly feasible to skip enrolling the custom keys and leave SecureBoot off.


<pre>
The page [[UEFI Secure Boot]] contains the instructions for setting an a UKI. Additionally, it is possible to install the UKI in the default fallback path used by most UEFI implementations. By installing the UKI into this path, the system will automatically boot into it if no other entries are defined. This can be automated as part of the kernel hook by adding the following to {{path|/etc/kernel-hooks.d/secureboot.conf}}
# bootctl update
</pre>


== Removing ==
{{cat|/etc/kernel-hooks.d/secureboot.conf|<nowiki># For the edge kernel, install the UKI into the default UEFI path.
if [ "$1" == "edge" ]; then
  output_dir="/efi/EFI/Boot/"
  output_name="bootx64.efi"
fi
</nowiki>}}


If for any reason you wish to not use systemd-boot anymore then the <code>bootctl</code> binary also provides a command for easily removing the files that were installed with the install command:
{{path|bootx64.efi}} is only correct for <code>x86_64</code> systems. For other architectures the exact name will vary.
 
<pre>
# bootctl remove
# apk del systemd-boot
</pre>


= External Links =
= See also =
* [https://wiki.gentoo.org/wiki/Bootloader Gentoo Wiki]
* [https://wiki.archlinux.org/title/Arch_boot_process#Boot_loader Archwiki]
* [https://wiki.postmarketos.org/wiki/Category:Bootloaders PostmarketOS Wiki]
* [https://www.denx.de/wiki/U-Boot/ReleaseCycle U-Boot Release Cycle]
* [https://www.denx.de/wiki/U-Boot/ReleaseCycle U-Boot Release Cycle]
* [https://wiki.archlinux.org/index.php/systemd-boot ArchWiki extensive article on systemd-boot]


[[Category:Installation]]
[[Category:Installation]]
[[Category:Booting]]
[[Category:Booting]]

Latest revision as of 16:34, 19 March 2024

This page shows the basic steps you need to perform, if you for any reason want to switch bootloaders or apply some manual configuration.

  • Syslinux is the default light-weight bootloader used in Alpine.
  • rEFInd is an easy to use EFI boot menu that allows booting different operating systems.
  • GRUB is a standard linux boot loader.
  • EFI Boot Stub allows booting linux directly from a motherboard supporting UEFI or another bootloader.
  • Gummiboot can be used for UEFI Secure Boot.

rEFInd

For (U)EFI systems, the refind package can provide a graphical EFI boot menu that allows to boot operating systems that are found on the available partitions.

If refind is not yet available in the used alpine release, it may be installed in another dual/multi-booted linux distribution.

For example, with a Debian based distribution, it can be installed to the EFI partition like this:

# apt install refind # installs the debian package # refind-install --alldrivers # installs refind to the EFI partition

(The --alldrivers option includes all filesystem drivers instead of only the one needed to load the currently running kernel, to allow finding and booting operating systems from more partitions.)

And a first (default) boot menu line needs to be configured with Alpine's default boot parameters. Assuming the bootable partition is mounted at /media/sdXY it can be done like this (at time of writing):

# echo '"Alpine" "modules=loop,squashfs,sd-mod,usb-storage quiet initrd=\boot\intel-ucode.img initrd=\boot\amd-ucode.img initrd=\boot\initramfs-lts"' > /media/sdXY/boot/refind_linux.conf

Note: At the time of writing, it was still needed to use backslashes in the .conf file.
The path in the config file needs to be relative to the partition that the kernel resides on. If /boot resides on its own separate partition, then \boot needs to be removed from the paths.

Syslinux

If you want to switch from another bootloader back to Syslinux, or if you for some reason want to install Syslinux manually, the following steps are required.

Install the syslinux package:

# apk add syslinux

If you're using GPT partitions, install the GPT MBR onto the drive you want to install the bootloader on (in this case /dev/sda):

# dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/gptmbr.bin of=/dev/sda

Or if you're using DOS partitions, install the DOS MBR instead:

# dd bs=440 count=1 conv=notrunc if=/usr/share/syslinux/mbr.bin of=/dev/sda


Next install the required Syslinux binaries. Despite being called extlinux, Syslinux supports booting from FAT12/16/32, NTFS, ext2/3/4, btrfs, XFS, and UFS/FFS filesystems.

# extlinux --install /boot

The configuration file is located in /boot/extlinux.conf. Alpine ships with a script called update-extlinux which automatically (re)generates this file, for example on updates to Syslinux. The settings for this script can be found in /etc/update-extlinux.conf, including the option to disable automatic overwriting of /boot/extlinux.conf. You can also place additional menu entries in the /etc/update-extlinux.d/ directory, e.g. for dual booting.


EFI

Todo: Work in progress. This should at least get you started.


Assuming /mnt is a FAT32 partition of type EF00 and /boot belongs to the rootfs created after running setup-disk:

# mkdir -p /mnt/EFI/syslinux # cp /usr/share/syslinux/efi64/* /mnt/EFI/syslinux/ # cp /boot/extlinux.conf /mnt/EFI/syslinux/syslinux.cfg # cp /boot/vmlinuz* /mnt/EFI/syslinux/ # cp /boot/initramfs* /mnt/EFI/syslinux/

You may need to modify /mnt/EFI/syslinux/syslinux.cfg to change the paths to absolute paths (just add a / in front of the vmlinuz/initramfs entries), or copy the files to /mnt/EFI/syslinux instead (XXX: untested).

At the end, the file /mnt/EFI/syslinux/syslinux.cfg should look like this:

Contents of /mnt/EFI/syslinux/syslinux.cfg

... DEFAULT menu.c32 PROMPT 0 MENU TITLE Alpine/Linux Boot Menu MENU HIDDEN MENU AUTOBOOT Alpine will be booted automatically in # seconds TIMEOUT 10 LABEL lts MENU DEFAULT MENU LABEL Linux lts LINUX /vmlinuz-lts INITRD /initrd-lts APPEND root=/dev/sda3 modules=sd-load,usb-storage,ext4 quiet

And finally, add syslinux to EFI boot menu (assuming /dev/sda is your hard drive)

# apk add efibootmgr # efibootmgr -c -d /dev/sda -p 1 -l \\EFI\\syslinux\\syslinux.efi -L "ALPINE-SYSLINUX"

You can now verify that the boot entry has been added

efibootmgr

BootCurrent: 0001
Timeout: 0 seconds
BootOrder: 0001,0000,0002,...
Boot001* ALPINE-SYSLINUX HD(1,GPT,xxxxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx)/FILE(\EFI\syslinux\syslinux.efi)

GRUB

To install GRUB in BIOS mode, (optionally) remove the Syslinux package and install the required GRUB packages:

# apk del syslinux # apk add grub grub-bios

For EFI, install GRUB's EFI package instead. Note that /boot has to be an EFI compatible filesystem like FAT32.

# apk add grub-efi efibootmgr

Next install the MBR and GRUB binaries to disk for BIOS mode:

# grub-install /dev/vda

For EFI mode:

# grub-install --target=x86_64-efi --efi-directory=/boot

then add this line to /etc/default/grub:

Contents of /etc/default/grub

# GRUB_CMDLINE_LINUX_DEFAULT="quiet rootfstype=ext4 modules=sd-mod,usb-storage,ext4"

GRUB ships with an automatic config generator, including some automatic detection of other operating systems installed on the device:

# grub-mkconfig -o /boot/grub/grub.cfg

This script can be configured via the /etc/default/grub file. See [1] for a list of available options.

EFI Boot Stub

To boot directly from your motherboard's UEFI boot menu, a boot entry needs to be created with either a UEFI shell or efibootmgr.

efibootmgr

Install efibootmgr:

# apk add efibootmgr

Create a boot entry. It's recommended to do this in a script, as efibootmgr does not allow editing entries.

Contents of add-bootentry

#!/bin/sh params="root=/dev/sdXZ rootfstype=ext4 rw \ initrd=\intel-ucode.img \ initrd=\initramfs-lts" efibootmgr --create --label "Alpine Linux" \ --disk /dev/sdX --part Y \ --loader /vmlinuz-lts \ --unicode "${params}" \ --verbose

Where /dev/sdXY contains the EFI partition and /dev/sdXZ contains the root partition. If you are using linux-edge, replace lts with edge in the script

Note:

The kernel contains the exhaustive list of ways to specify the block device. For a more robust boot entry, it is recommended to use a persistent name such as the PARTUUID.

Optionally, set the newly created entry as the default:

# efibootmgr -n XXXX

Where XXXX is the boot number of the new entry.

Note: The loader and initrd file arguments are relative to the EFI partition. In a default installation, alpine places these files in /boot/, while EFI is mounted to /boot/efi/. You can either update fstab to mount EFI at /boot/, or manually copy them to /boot/efi/.

Using a UKI (UEFI only)

It is possible to boot directly into a Unified Kernel Image (UKI). A UKI is a single file which contains the initfs, kernel and cmdline. While this is typically done in order to enable SecureBoot, it is perfectly feasible to skip enrolling the custom keys and leave SecureBoot off.

The page UEFI Secure Boot contains the instructions for setting an a UKI. Additionally, it is possible to install the UKI in the default fallback path used by most UEFI implementations. By installing the UKI into this path, the system will automatically boot into it if no other entries are defined. This can be automated as part of the kernel hook by adding the following to /etc/kernel-hooks.d/secureboot.conf

Contents of /etc/kernel-hooks.d/secureboot.conf

# For the edge kernel, install the UKI into the default UEFI path. if [ "$1" == "edge" ]; then output_dir="/efi/EFI/Boot/" output_name="bootx64.efi" fi

bootx64.efi is only correct for x86_64 systems. For other architectures the exact name will vary.

See also