I edited that line in /etc/default/grub so it reads:
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash usbcore.dyndbg=+p"
However, I don't see any changes in dmesg after I reboot:
[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-52-generic root=UUID=e5e53ee1-0a10-48ee-8f7c-1d553ecc5607 ro quiet splash vt.handoff=1
I edited that line in /etc/default/grub so it reads:
GRUB_CMDLINE_ LINUX_DEFAULT= "quiet splash usbcore.dyndbg=+p"
However, I don't see any changes in dmesg after I reboot:
[ 0.000000] Command line: BOOT_IMAGE= /boot/vmlinuz- 4.15.0- 52-generic root=UUID= e5e53ee1- 0a10-48ee- 8f7c-1d553ecc56 07 ro quiet splash vt.handoff=1