On Sat, Jan 14, 2017 at 10:50:47AM +0100, Hans wrote:
Hi list, this is the situation:I have debian installed on my first harddrive and kali-linux on my secondharddrive. When a new kernel version is installed, update-grub is always editing both harddrives. Is there a way, to avoid this? So, I do not want, that an upgrade of the kali-kernel touches the grub installation of the first harddrive with debian and vice versa. If this is not possible, I would also be happy to know.
As noted by Pascal, update-grub only recreates grub's config, but let's clarify some of the workings of grub to see where your problem lies.
BIOS will typically only boot from one drive (That said, both BIOS and UEFI often have mechanisms to choose what that drive is). When grub is installed to a drive, it will use the grub.cfg from that drive (I'm not sure if that's built in, or if it's an assumption that grub makes, but let's take it as read). That grub.cfg can then be used to start operating systems on any drive.
So, I think what you're wanting is A) Debian's grub pointing to Debian's grub.cfg, booting Debian and Kali AND B) Kali's grub pointing to Kali's grub.cfg, booting Kali and Debian.
For that, run "dpkg-reconfigure -plow grub-pc" (or whichever build of grub you're using: grub-efi-*, grub-coreboot etc. Note that you're reconfiguring the application package itself, NOT an auxiliary package such as 'grub2' or 'grub' or 'grub-common'). This *should* ask you to which drives you want grub installed. This will update the grub image embedded at the start of the drive(s) that you select. In theory, then, deselecting the Kali drive should mean that all data on the Kali drive is untouched (by grub).
If, additionally, you want Debian's grub to ONLY boot Debian and Kali's grub to ONLY boot Kali, then you should uninstall the "os-prober" package and re-run update-grub. Basically, the normal assumption is that ONE operating system is in charge of the bootloader, but you still want to be able to boot other operating systems, so update-grub calls os-prober which scans your system for other operating systems and adds them into the list. If you remove os-prober, grub will only know about itself.
Hope that helps.
Best Hans
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