1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
|
#+TITLE: install-archzfs leaves broken mkinitcpio configuration
#+DATE: 2026-01-22
* Problem Summary
After installing Arch Linux with ZFS via install-archzfs, the system has incorrect mkinitcpio configuration that can cause boot failures. The configuration issues are latent - the system may boot initially but will fail after any mkinitcpio regeneration (kernel updates, manual rebuilds, etc.).
* Root Cause
The install-archzfs script does not properly configure mkinitcpio for a ZFS boot environment. Three issues were identified:
** Issue 1: Wrong HOOKS in mkinitcpio.conf
The installed system had:
#+begin_example
HOOKS=(base systemd autodetect microcode modconf kms keyboard keymap sd-vconsole block filesystems fsck)
#+end_example
This is wrong for ZFS because:
- Uses =systemd= init hook, but ZFS hook is busybox-based and incompatible with systemd init
- Missing =zfs= hook entirely
- Has =fsck= hook which is unnecessary/wrong for ZFS
Correct HOOKS for ZFS:
#+begin_example
HOOKS=(base udev autodetect microcode modconf kms keyboard keymap consolefont block zfs filesystems)
#+end_example
** Issue 2: Leftover archiso.conf drop-in
The file =/etc/mkinitcpio.conf.d/archiso.conf= was left over from the live ISO:
#+begin_example
HOOKS=(base udev microcode modconf kms memdisk archiso archiso_loop_mnt archiso_pxe_common archiso_pxe_nbd archiso_pxe_http archiso_pxe_nfs block filesystems keyboard)
COMPRESSION="xz"
COMPRESSION_OPTIONS=(-9e)
#+end_example
This drop-in OVERRIDES the HOOKS setting in mkinitcpio.conf, so even if mkinitcpio.conf were correct, this file would break it.
** Issue 3: Wrong preset file
The file =/etc/mkinitcpio.d/linux-lts.preset= contained archiso-specific configuration:
#+begin_example
# mkinitcpio preset file for the 'linux-lts' package on archiso
PRESETS=('archiso')
ALL_kver='/boot/vmlinuz-linux-lts'
archiso_config='/etc/mkinitcpio.conf.d/archiso.conf'
archiso_image="/boot/initramfs-linux-lts.img"
#+end_example
Should be:
#+begin_example
# mkinitcpio preset file for linux-lts
PRESETS=(default fallback)
ALL_kver="/boot/vmlinuz-linux-lts"
default_image="/boot/initramfs-linux-lts.img"
fallback_image="/boot/initramfs-linux-lts-fallback.img"
fallback_options="-S autodetect"
#+end_example
* How This Manifests
1. Fresh install appears to work (initramfs built during install has ZFS support somehow)
2. System boots fine initially
3. Kernel update or manual =mkinitcpio -P= rebuilds initramfs
4. New initramfs lacks ZFS support due to wrong config
5. Next reboot fails with "cannot import pool" or "failed to mount /sysroot"
* Fix Required in install-archzfs
The script needs to, after arch-chroot setup:
1. *Set correct mkinitcpio.conf HOOKS*:
#+begin_src bash
sed -i 's/^HOOKS=.*/HOOKS=(base udev autodetect microcode modconf kms keyboard keymap consolefont block zfs filesystems)/' /mnt/etc/mkinitcpio.conf
#+end_src
2. *Remove archiso drop-in*:
#+begin_src bash
rm -f /mnt/etc/mkinitcpio.conf.d/archiso.conf
#+end_src
3. *Create proper preset file*:
#+begin_src bash
cat > /mnt/etc/mkinitcpio.d/linux-lts.preset << 'EOF'
# mkinitcpio preset file for linux-lts
PRESETS=(default fallback)
ALL_kver="/boot/vmlinuz-linux-lts"
default_image="/boot/initramfs-linux-lts.img"
fallback_image="/boot/initramfs-linux-lts-fallback.img"
fallback_options="-S autodetect"
EOF
#+end_src
4. *Rebuild initramfs after fixing config*:
#+begin_src bash
arch-chroot /mnt mkinitcpio -P
#+end_src
* Recovery Procedure (for affected systems)
Boot from archzfs live ISO, then:
#+begin_src bash
# Import and mount ZFS
zpool import -f zroot
zfs mount zroot/ROOT/default
mount /dev/nvme0n1p1 /boot # adjust device as needed
# Fix mkinitcpio.conf
sed -i 's/^HOOKS=.*/HOOKS=(base udev autodetect microcode modconf kms keyboard keymap consolefont block zfs filesystems)/' /etc/mkinitcpio.conf
# Remove archiso drop-in
rm -f /etc/mkinitcpio.conf.d/archiso.conf
# Fix preset (adjust for your kernel: linux, linux-lts, linux-zen, etc.)
cat > /etc/mkinitcpio.d/linux-lts.preset << 'EOF'
PRESETS=(default fallback)
ALL_kver="/boot/vmlinuz-linux-lts"
default_image="/boot/initramfs-linux-lts.img"
fallback_image="/boot/initramfs-linux-lts-fallback.img"
fallback_options="-S autodetect"
EOF
# Mount system directories for chroot
mount --rbind /dev /dev
mount --rbind /sys /sys
mount --rbind /proc /proc
mount --rbind /run /run
# Rebuild initramfs
chroot / mkinitcpio -P
# Reboot
reboot
#+end_src
* Machine Details (ratio)
- Two NVMe drives in ZFS mirror (nvme0n1, nvme1n1)
- Pool: zroot
- Root dataset: zroot/ROOT/default
- Kernel: linux-lts 6.12.66-1
- Boot partition: /dev/nvme0n1p1 (FAT32, mounted at /boot)
* Related Information
The immediate trigger for discovering this was a system freeze during mkinitcpio regeneration. That freeze was caused by the AMD GPU VPE power gating bug (separate issue - see archsetup NOTES.org for details). However, the system's inability to boot afterward exposed these latent mkinitcpio configuration problems.
|
