I have a SUN Ultra10, a few years ago I installed debian9 on a disk. now I tried to install debian12 (with grub) on another disk but it doesn't boot. I tried to boot deb12 from deb9 with silo, but it start kernel of debian9 with the " /" of 12what do you suggest I try?
Adrian has suggested to use kernel 4.19 until the issues with newer kernels can be sorted out. Search the list archive for the thread "Linux kernel stability fixes for older SPARCs​", he also gave a suggestion on how to install older kernels from the Debian archive.
