** Description changed:
[Impact]
- Crash kernels include an obsolete "nousb" parameter by default, which can
cause confusion since it's been deprecated in newer kernel versions.
+ * Kdump command-line include an obsolete "nousb" parameter by default, which
can cause a misimpression: users will think they are not booting with USB, but
they are.
- [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").
+ * 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 appears to be saying the
- opposite.
+ * USB may be pretty essential in case for example kdump users need to
+ decrypt a disk under LUKS, and there's only an USB keyboard connected to
+ the system. Given the option is innocuous since Bionic, we should just
+ drop it to prevent confusion.
- 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 '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 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.
+
+ The regression potential is extremely low, since the "nousb" parameter
+ is not used since Bionic although is there. Any bugs we would have by
+ changing this are still valid by not removing the option - the semantics
+ with or without "nosub" is the same since from Bionic.
+
+ NOTICE we won't change Xenial, it can use kernel 4.4 which indeed
+ disables USB by taking the "nousb" parameter.
--
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https://bugs.launchpad.net/bugs/1800562
Title:
Remove obsolete "nousb" option in kdump command-line for newer kernels
Status in makedumpfile package in Ubuntu:
Confirmed
Status in makedumpfile source package in Xenial:
Won't Fix
Status in makedumpfile source package in Bionic:
In Progress
Status in makedumpfile source package in Cosmic:
In Progress
Status in makedumpfile source package in Disco:
Confirmed
Status in makedumpfile source package in Eoan:
Confirmed
Bug description:
[Impact]
* Kdump command-line include an obsolete "nousb" parameter by default, which
can cause a misimpression: users will think they are not booting with USB, but
they are.
* 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").
* USB may be pretty essential in case for example kdump users need to
decrypt a disk under LUKS, and there's only an USB keyboard connected
to the system. Given the option is innocuous since Bionic, we should
just drop it to prevent confusion.
[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 '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 extremely low, since the "nousb" parameter
is not used since Bionic although is there. Any bugs we would have by
changing this are still valid by not removing the option - the
semantics with or without "nosub" is the same since from Bionic.
NOTICE we won't change Xenial, it can use kernel 4.4 which indeed
disables USB by taking the "nousb" parameter.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/makedumpfile/+bug/1800562/+subscriptions
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