** 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

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