I seem to have a problem with grub being read-only after sudo apt update & apt upgrade on my iBook G4:
Setting up grub-ieee1275 (2.06-5) ... Installing for powerpc-ieee1275 platform. grub-install: error: cannot backup `/boot/grub/powerpc- ieee1275/adler32.mod': Read-only file system. Failed: grub-install --target=powerpc-ieee1275 WARNING: Bootloader is not properly installed, system may not be bootable /usr/sbin/grub-mkconfig: 270: cannot create /boot/grub/grub.cfg.new: Read-only file system dpkg: error processing package grub-ieee1275 (--configure): installed grub-ieee1275 package post-installation script subprocess returned error exit status 2 Setting up linux-image-6.0.0-4-powerpc (6.0.8-1) ... /etc/kernel/postinst.d/initramfs-tools: update-initramfs: Generating /boot/initrd.img-6.0.0-4-powerpc /etc/kernel/postinst.d/zz-update-grub: /usr/sbin/grub-mkconfig: 270: cannot create /boot/grub/grub.cfg.new: Read-only file system run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 2 dpkg: error processing package linux-image-6.0.0-4-powerpc (-- configure): installed linux-image-6.0.0-4-powerpc package post-installation script subprocess returned error exit status 1 dpkg: dependency problems prevent configuration of linux-image-powerpc: linux-image-powerpc depends on linux-image-6.0.0-4-powerpc (= 6.0.8- 1); however: Package linux-image-6.0.0-4-powerpc is not configured yet. dpkg: error processing package linux-image-powerpc (--configure): dependency problems - leaving unconfigured Setting up linux-image-5.19.0-1-powerpc (5.19.6-1) ... /etc/kernel/postinst.d/initramfs-tools: update-initramfs: Generating /boot/initrd.img-5.19.0-1-powerpc /etc/kernel/postinst.d/zz-update-grub: /usr/sbin/grub-mkconfig: 270: cannot create /boot/grub/grub.cfg.new: Read-only file system run-parts: /etc/kernel/postinst.d/zz-update-grub exited with return code 2 dpkg: error processing package linux-image-5.19.0-1-powerpc (-- configure): installed linux-image-5.19.0-1-powerpc package post-installation script subprocess returned error exit status 1 Errors were encountered while processing: grub-ieee1275 linux-image-6.0.0-4-powerpc linux-image-powerpc linux-image-5.19.0-1-powerpc E: Sub-process /usr/bin/dpkg returned an error code (1)