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Appendix: small changes to the discussion of initramfs

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John McQuah 2022-08-05 21:18:04 -04:00
parent 76da8513a8
commit b3e68d715a
1 changed files with 16 additions and 13 deletions
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crux-wiki/Handbook3-7-Appendix
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@ -200,26 +200,30 @@ $ cp /usr/src/linux-5.15.55/arch/x86/boot/bzImage vmlinuz-5.15.55.efi
$ efibootmgr -c -d /dev/sda -L 'Linux 5.15.55' -l '\BOOT\vmlinuz-5.15.55.efi' -u 'root=/dev/sda2'
* For maximum portability, you can also identify the root filesystem using its
partition UUID. Run @@ls /dev/disk/by-partuuid/@@ to discover the UUID of the
-> For maximum portability, you can also identify the root filesystem using its
partition UUID. Run @@ls -l /dev/disk/by-partuuid/@@ to discover the UUID of the
known partitions, and then modify the @@efibootmgr@@ arguments to use the
identifier of the root partition. '''Note: this option is more fragile than
specifying the root partition using its device node, because of the delay in
scanning all partitions to construct the list of their UUIDs.'''
scanning all partitions to construct the list of their UUIDs. If you encounter
an error when booting your CRUX system this way, you will have to use the
installation media (or another rescue disk) to recreate the EFI boot entry with
device node instead, or with an additional boot option that gives the kernel more
time to enumerate the partitions.'''
$ efibootmgr -c -d /dev/sda -L 'Linux 5.15.55' -l '\BOOT\vmlinuz-5.15.55.efi' -u 'root=PARTUUID=c3259ad5-...'
* Finally, change the boot order so that the newly-created boot entry is the
first one tried. Start by finding the number assigned to the newly-created
entry, and then use that number to specify the desired boot order.
entry, and then use that number to specify the desired boot order. EXAMPLE:
[@
$ efibootmgr
BootCurrent: 0000
Timeout: 1 seconds
BootOrder: 0000,0001
Boot0000* Linux 5.15.26 HD(1,GPT,d5a44413-5bea-b24c-b4b7-76b32d5d2ed4,0x800,0x64000)/File(\BOOT\vmlinuz-5.15.26.efi)72006f006f0074...
Boot0001* Linux 5.15.55 HD(1,GPT,d5a44413-5bea-b24c-b4b7-76b32d5d2ed4,0x800,0x64000)/File(\BOOT\vmlinuz-5.15.55.efi)72006f006f0074...
Boot0000* Linux 5.15.26 HD(1,GPT,d5a44413-...,0x800,0x64000)/File(\BOOT\vmlinuz-5.15.26.efi)72006f006f0074...
Boot0001* Linux 5.15.55 HD(1,GPT,d5a44413-...,0x800,0x64000)/File(\BOOT\vmlinuz-5.15.55.efi)72006f006f0074...
$ efibootmgr -o 0001,0000
@]
@ -233,7 +237,7 @@ modules to initialize other hardware) is that the root filesystem is not a
physical volume, but rather a logical volume inside an encryption layer like
LUKS. To handle this situation, you will need to go beyond the kernel building
process outlined above, and also create a compressed filesystem image (called an
''initramfs'') that contains the lvm and cryptsetup packages (and the drivers
''initramfs'') that contains the lvm2 and cryptsetup packages (and the drivers
for usb input devices, if you chose not to compile them into the kernel).
Creating such an initramfs was once an intricate procedure, but tools like
'''dracut''' make it much simpler these days.
@ -248,9 +252,8 @@ section of the appendix just points to a separate document, where an
[[https://gitlab.com/SiFuh/Documentation/-/blob/master/CRUX-3.6-Encrypted.txt | outline for installing CRUX with full-disk encryption]]
is given from beginning to end. Even if full-disk encryption is not your desired
endpoint and you just want to learn more about highly-modular kernel configs,
the creation of an initramfs is best viewed in the context of the overall
installation procedure, after having successfully built some less-modular
kernels yourself. Studying the upstream documentation for any unfamiliar command
in the linked outline (eg., %fn%cryptsetup%%, %fn%pvcreate%%, or %fn%dracut%%)
is an excellent way to distinguish the functions performed by the various
components.
the need for an initramfs is easier to motivate by considering a specific use
case like full-disk encryption. Studying the upstream documentation for any
unfamiliar command in the linked outline (eg., %fn%cryptsetup%%, %fn%pvcreate%%,
or %fn%dracut%%) is an excellent way to distinguish the functions performed by
the various components.