Presently running Ubuntu 17.10 and using the grub bootloader. This is on my main drive (/dev/sda). After installing Solus on my usb external hard drive (/dev/sdb) i ran sudo update-grub in ubuntu to find Solus bootloader. Now when i boot up i get a list that has GOOFIBOOT in it. I need to enable the kernel command parameter of amd_iommu=off in order to boot kernel 4.12. A fix was made in kernel 4.13 so that I can use my iommu. However I need to know how to apply this kernel parameter from grub on the goofiboot line in order to update to the latest kernel (or the system just crashes). I attempted to edit the goofiboot line in grub and simply type amd_iommu=off which did not work (brought up the usual errors when i am not running kernel 4.13). Can anyone provide me with any advice to make this work?