On Fri, Jul 19, 2019 at 8:27 PM Mick <[email protected]> wrote:
> On Friday, 19 July 2019 10:29:09 BST Adam Carter wrote: > > This > > https://wiki.gentoo.org/wiki/GRUB2/Configuration_variables > > > > has > > > > GRUB_DISABLE_LINUX_UUID false If true, ${GRUB_DEVICE} is passed in the > root > > parameter on the kernel command line. > > > > If false, ${GRUB_DEVICE_UUID} is passed in the root parameter on the > kernel > > command line when an initramfs is available. > > > > So it looks like i can't set root= to a UUID unless i use an initramfs - > > can anyone confirm? > > This would be correct if GRUB (with/out initramfs) happened to be the only > way > to configure Linux. Thankfully we have more choices, in Gentoo at least. > ;-) > > > > In /usr/src/linux/admin-guide/kernel-parameters.txt it has; > > root= [KNL] Root filesystem > > See name_to_dev_t comment in init/do_mounts.c. > > > > And in do_mounts.c it mentions PARTUUID= and PARTLABEL= but i dont know C > > so don't know what to make of it. > > > > Background is that after adding a new disk the system doesn't boot, so > i'm > > assuming that the /dev/sdX device names are now pointing to different > > hardware, so i want to fix that by using persistent names. > > You could use UUID, or partition label (if GPT is used on the disk), but > by- > pass GRUB's facility to configure the UUID and use the kernel .config > itself. > For this you will have to configure and compile your own kernel. Use this > kernel option to specify kernel command line options: I experimented found the following worked in /etc/default/grub; GRUB_DEVICE="PARTUUID=d3554d49-02" Which writes grub.cfg as; linux /vmlinuz-5.2.0-gentoo root=PARTUUID=d3554d49-02 ro init=/usr/lib/systemd/systemd iommu=pt raid=noautodetect PARTUUID looked up with blkid. No initramfs required :)
