here's v2 based on some IRC feedback (grammar- and punctuation-related)
I am planning to add for tomorrow.
Title: Multiple root kernel command-line arguments
Author: Thomas Deutschmann
Due to genkernel-4.1 development which is changing device manager
from MDEV to (E)UDEV it was noticed that some tools like kexec
append an additional root argument to kernel command-line. If these
tools will set root to a non-persistent device name like
root=/dev/dm-3, the next boot might fail if there is *no* root device
named like that in start environment (i.e. initramfs).
While kexec's runscript was changed in >=sys-apps/kexec-tools-2.0.20-r2
to no longer append root kernel command-line argument when an option
like "--reuse-cmdline" (default) is used, a cold reboot *without*
kexec may be needed to restore kernel command-line.
NOTE: This issue is *not* specific to kexec or genkernel usage.
Kernel will always use last set root kernel command-line argument.
Any tool which might be appending root argument without a persistent
device name might cause a boot failure if system cannot find that
referenced root device during boot.
To avoid boot problems, user should revise their current kernel
command-line (/proc/cmdline) to ensure that only *one* root kernel
command-line argument is set. The usage of persistent device names
like root=UUID=<...> is highly recommended.
Thomas Deutschmann / Gentoo Linux Developer
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