Adding options to grub

[Mauricio Tavares]

So I want to add a few options to the kernel (say iommu support). I
have been told before to avoid using grub2-mkconfig because it would
apply the changes to all currently available (to boot from) boot
kernels. Instead, I should edit just the latest kernel entry in the
grub.cfg file, adding the option to the line starting with linux16.
This way, if it went boink, all I had to do is reboot, pick another
kernel from the grub menu and off I went. And, it seems that every
future kernel upgrade would incorporate this change.

Is that accurate or is there a cleaner way to do the same while still
leaving me the option to go back to the grub menu?