Breakpoints in bootloader assembly

I am trying to setup breakpoints in my bootloader before my the main()
function gets called. For instance, I would like be able to set a
breakpoint at the beginning of the StartUp function which is written
in assembly. I have no problem setting breakpoints for C functions,
for example I can create a new breakpoint and just type "main" into
the New Breakpoint dialog. I can also set a HW breakpoint using the
address of main (in my case 0x9000c1c0) and that works too. Trying to
enter "StartUp" rather than "main" doesn't work, nor does using its
address. I have noticed that the symbol "StartUp" isn't seen in my
bootloader executable like "main" is (as inspected with dumpbin). Any
suggestions of what I might be doing wrong would be appreciated.