Gentoo Archives: gentoo-dev

From: Thomas Deutschmann <whissi@g.o>
To: gentoo development <gentoo-dev@l.g.o>
Subject: [gentoo-dev] News item v2: Multiple root kernel command-line arguments
Date: Thu, 06 Aug 2020 11:38:25
1 Hi,
3 here's v2 based on some IRC feedback (grammar- and punctuation-related)
4 I am planning to add for tomorrow.
7 ---
8 Title: Multiple root kernel command-line arguments
9 Author: Thomas Deutschmann <whissi@g.o>
10 Posted: 2020-08-05
11 Revision: 1
12 News-Item-Format: 2.0
14 Due to genkernel-4.1 development which is changing device manager
15 from MDEV to (E)UDEV it was noticed that some tools like kexec
16 append an additional root argument to kernel command-line. If these
17 tools will set root to a non-persistent device name like
18 root=/dev/dm-3, the next boot might fail if there is *no* root device
19 named like that in start environment (i.e. initramfs).
21 While kexec's runscript was changed in >=sys-apps/kexec-tools-2.0.20-r2
22 to no longer append root kernel command-line argument when an option
23 like "--reuse-cmdline" (default) is used, a cold reboot *without*
24 kexec may be needed to restore kernel command-line.
26 NOTE: This issue is *not* specific to kexec or genkernel usage.
27 Kernel will always use last set root kernel command-line argument.
28 Any tool which might be appending root argument without a persistent
29 device name might cause a boot failure if system cannot find that
30 referenced root device during boot.
32 To avoid boot problems, user should revise their current kernel
33 command-line (/proc/cmdline) to ensure that only *one* root kernel
34 command-line argument is set. The usage of persistent device names
35 like root=UUID=<...> is highly recommended.
38 --
39 Regards,
40 Thomas Deutschmann / Gentoo Linux Developer
41 C4DD 695F A713 8F24 2AA1 5638 5849 7EE5 1D5D 74A5


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Subject Author
Re: [gentoo-dev] News item v2: Multiple root kernel command-line arguments "Jason A. Donenfeld" <zx2c4@g.o>