Hello everyone,
Is it possible to specify mount options for ESP, root and LUKS devices
when using automatic partition discovery and mounting with no fstab?
I got a new Arch Linux installation to boot without fstab, crypttab or
specifying the `root/luks.uuid` kernel options, however the
`luks.options=discard` and `rootflags=noatime` aren't honored. I have
read man systemd-cryptsetup-generator, systemd-fstab-generator and
systemd-remount-fs and can't seem to find the answer so as to why those
settings aren't passed down.
My setup is as follow:
+----------------------------+ +---------------------------+
| | | |
| EFI System Partition (ESP) | | LUKS encrypted partition |
| | | |
| /dev/nvme0n1p1 | | /dev/nvme0n1p2 |
| FAT32 | | XFS |
| | | |
| mounted on /efi | | mounted on / |
| | | |
+----------------------------+ +---------------------------+
* partitioning was done using Partition Type GUIDs following the
Discoverable Partition Specification:
# sgdisk --zap-all --clear /dev/nvme0n1 \
--new=1:0:+488M --typecode=1:ef00 --change-name=1:"EFI System
Partition" \
--new=2:0:0 --typecode=2:8304 --change-name=2:"Linux LUKS"
# fdisk -l /dev/nvme0n1
...
Device Start End Sectors Size Type
/dev/nvme0n1p1 2048 1001471 999424 488M EFI System
/dev/nvme0n1p2 1001472 1000215182 999213711 476.5G Linux root (x86-64)
* initramfs uses systemd with the following mkinitcpio hooks:
$ grep systemd /etc/mkinitcpio.conf
HOOKS=(base systemd autodetect keyboard sd-vconsole modconf block
sd-encrypt filesystems fsck)
* systemd-boot is used to load a unified EFI kernel image made with:
```
objcopy \
--add-section .osrel="/usr/lib/os-release" --change-section-vma
.osrel=0x20000 \
--add-section .cmdline="cmdline.txt" --change-section-vma
.cmdline=0x30000 \
--add-section .splash="/usr/share/systemd/bootctl/splash-arch.bmp"
--change-section-vma .splash=0x40000 \
--add-section .linux="vmlinuz-linux" --change-section-vma
.linux=0x2000000 \
--add-section .initrd="ucode-initrd.img" --change-section-vma
.initrd=0x3000000 \
"/usr/lib/systemd/boot/efi/linuxx64.efi.stub"
"/efi/EFI/Linux/linux.efi"
```
$ cat cmdline.txt
luks.options=discard rootflags=noatime
$ bootctl list
Boot Loader Entries:
title: Arch Linux (default)
id: linux.efi
source: /efi/EFI/Linux/linux.efi
linux: EFI/Linux/linux.efi
options: luks.options=discard rootflags=noatime
Logs show the correct command line:
journalctl -b | grep noatime
nov. 27 21:32:16 archlinux kernel: Command line: luks.options=discard
rootflags=noatime
However once booted:
$ findmnt /
TARGET SOURCE FSTYPE OPTIONS
/ /dev/mapper/root xfs
rw,relatime,attr2,inode64,logbufs=8,logbsize=32k,noquota
# dmsetup table
root: 0 999180943 crypt aes-xts-plain64
:64:logon:cryptsetup:LUKS-U-U-I-D-xx 0 259:2 32768
I have tried specifying the LUKS header UUID as in
`luks.option=UUID=discard`, using different wording like discards,
allow-discards, allow_discards... and using the `rw` option but to no avail.
For LUKS I know I can set the desired flags using `cryptsetup refresh`
and make them permanent with the `--persistent` option, but I would like
to know whether it is possible using just systemd and kernel options. As
for rootflags, I am even more at a loss so as to why it isn't honored.
It is likely to be something I don't understand in how systemd works in
early boot or maybe it is simply not possible, but from the doc it looks
like it should. Could someone shed some light on this issue?
Bonus question: is setting mount options for the ESP doable via the same
means, otherwise than manualy editing efi.mount?
Thanks and regards,
Bastien
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