** Description changed:
[Impact]
- Crash kernels come up with the usb subsystem enabled, even when it should be
disabled by default.
+ Crash kernels include an obsolete "nousb" parameter by default, which can
cause confusion since it's been deprecated in newer kernel versions.
[Description]
Since kernel v4.5, the correct parameter to disable USB subsystem
initialization is "usbcore.nousb" always (instead of "nousb" in case the
subsystem is built-in). This was changed by commit 097a9ea0e48 ("usb: make
"nousb" a clear module parameter").
We need to take this into account in kdump-tools, or else we may boot
- with USB in kdump even the command-line saying the opposite.
+ with USB in kdump even the command-line appears to be saying the
+ opposite.
This affects Xenial onwards, since the system may be running an HWE or
other supported v4.5+ kernel.
[Test Case]
1) Deploy a Disco VM e.g. with uvt-kvm
2) Install the kdump-tools package
- 3) Run `kdump-config test`and check for the 'usbcore.nousb' parameter:
+ 3) Run `kdump-config test`and check for the 'nousb' parameter:
$ kdump-config test
...
kexec command to be used:
/sbin/kexec -p --command-line="BOOT_IMAGE=/boot/vmlinuz-4.15.0-45-generic
root=LABEL=cloudimg-rootfs ro console=tty1 console=ttyS0 nr_cpus=1
systemd.unit=kdump-tools.service irqpoll nousb ata_piix.prefer_ms_hyperv=0"
/var/lib/kdump/vmlinuz
[Regression Potential]
- The regression potential is very low, since it doesn't need any changes in
makedumpfile and we're only adding a parameter on the crashkernel cmdline.
- According to kernel documentation [0], unknown parameters will be ignored if
they contain a dot (usbcore.nousb), so this change should have no impact on
v4.4 and earlier kernels.
- Nonetheless, the fix will be tested with autopkgtests and normal kdump
use-case scenarios.
-
- [0] https://www.kernel.org/doc/Documentation/admin-guide/kernel-
- parameters.rst
+ The regression potential is extremely low, since it doesn't need any changes
in makedumpfile code and we're only removing an already ineffective parameter
from the crashkernel cmdline. Nonetheless, patches will be tested with
autopkgtests and normal kdump use-case scenarios.
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https://bugs.launchpad.net/bugs/1800562
Title:
Remove obsolete "nousb" option in kdump command-line for newer kernels
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