GRUB not working with BIOS serial redirection

[Liberty Young]

On our single board computers, we had CVS grub working just fine after
one modification. Our BIOS also does transparent serial redirection (we
are using General Software's BIOS), and i too saw the same thing
happen...Grub would boot up, then freeze...at first, it thought the
problem was with the serial redirection stuff, but that wasn't it. GRUB
would freeze after going into an endless loop trying to switch to
procted mode via a GATE A20...as there wasn't a keyboard controller on
the embedded product, it never left it. Perhaps this is what you are
also experiencing?