Earlier today, I attempted to re-install Kali Linux on my machine (dual booted with Windows). To accomplish this, I downloaded the ISO and put it on my Easy2Boot USB stick. In order to get my laptop to boot from the Easy2Boot stick, I needed to go to my BIOS and:
- Disable PTT
- Enable Legacy Option ROM
- Switch to Legacy mode
This due to the fact that Easy2Boot doesn't support UEFI, and so the stick won't appear unless I do this.
I had no problems during the installation, but rather afterwards. I was fine booting into the system, but if I reverted the changes I made in the BIOS and returned to UEFI mode, I got the GRUB rescue prompt instead of Kali. Additionally, whilst those BIOS options were still set, GRUB couldn't detect my Windows installation. Ultimately, I used Rufus to install Kali with "Partition Scheme: GPT" and "Target System: UEFI (non CSM)". Upon doing this, I entered the installation process. Notably, the installer seemed to be different. Not only was it a different in its appearance, but the initial menu had different options.
How is it that switching between Legacy mode and UEFI mode has caused these problems? My understanding was that the only involvement that the MBR / GPT had in terms of booting was to provide the initial code from which to boot from.
Since GRUB was able to load in UEFI mode, why did it end up in recovery mode instead of continuing to boot Kali simply because of this change?
Why was there a difference between the installers I saw when in Legacy vs UEFI mode?
When in Legacy mode, why was GRUB unable to detect Windows? I would have thought that since the BIOS had already done its job in loading up GRUB, then it would have no problems, considering I know that GRUB has no problems detecting Windows when installed in UEFI mode.