Quick question re: dual-booting

[Pokala, Ravi]

Hi folks,

For doing some apples-to-apples comparisons on a piece of hardware, we
want to be able to easily flip back and forth between FreeBSD (10.1,
amd64, traditional non-UEFI bootstrap w/ GPT) and Linux. To minimize the
chance of an installer going wrong and nuking something, we're installing
one drive, installing FreeBSD on it, then swapping in another drive and
installing Linux on it. Then we'll install both drives, and let the
bootloader control which one gets booted.

The question is: how do we tell the bootloader which OS to boot? If we can
do it using loader, great! If we have to use something like grub, that's
fine too. But either way, I need some guidance.

Thoughts?

Thanks,

Ravi