During the early days of Debian Linux, one could get away with a 100mb boot partition. With the explosion of included firmware files in the initramfs file, the boot directory needs to be 500mb or even 1gb in size. I have a couple older machines I have not yet rebuilt, which have limited size. I resort to copying various initrd.img files in and out as I upgrade kernels or boot into older versions of the kernel.
Sometimes I have forgotten to properly copy an image back into /boot and run update-grub. When I do that, I have to boot into grub and run the grub command line. Some commands that I run are as follows:
Set a variable so when requesting help, you can page through entries:
grub> set pager=1
List the various mount points:
grub> ls
List the files in a particular mount point
grub> ls (hd0,msdos2)/root
Startup commands, depending upon where linux and initrd files are found:
grub> set root=(hd0,msdos2) grub> linux (hd0,msdos1)/vmlinux-6.1.0-15-amd64 root=LABEL=main grub> initrd (hd0,msdos2)/root/initramfs/initrd.img-6.1.0-15-amd64 grub> boot
