I'm installing Linux Mint in a new partition (I have other partitions with other variants of Linux). I'm tentatively putting the boot loader into /dev/sda which means that the Linux Mint boot loader will be the primary one. Does this mean that I can still access my other Linux partitions via this boot loader?
Is the whole device.
Would be the first partition on the device.
The boot loader would normally inhabit the first 512 bytes of the device. Plus additional spots, because the boot loader is larger than 512 bytes, that is not applicable to this conversation.
When installing a new OS, like Mint, and the boot loader is (re)installed, it will overwrite the existing boot loader, and here is the part to note, will now point to the configuration file (if grub) that lives on the new partition. Example:
/dev/sda3. So the boot loader menu you now see is the one that is created from the configuration file on the new partition.
- Normal grub install.
... and yes the new boot loader will be able to access the existing partitions.