My device has an SSD ( with Linux and Windows on it) and and HDD for data with some ISO images on it.

Whenever I run ls on grub command line, I only get the first disk with its partitions only and the other disk is not detected by grub and I can't boot my disk images from there. This is most probably because I have fast boot enabled in my BIOS settings (I'm booting legacy if that matters). When it's disabled or I manually boot the SSD, grub detects the HDD normally.

So my question is, how do I get grub the see my other disk without disabling fast boot in bios? ( It once mattered alot before I updated my bios), is there a grub module I need to load first or something to get grub to see the HDD like an OS does ?