Need READ Access to BIOS ROM

After the OS (Windows XP Embedded)and a single C++ application is up and running, I need that application to read several bytes of data from the BIOS ROM. The data to be read is checksum-type information which will have been previously stored in the BIOS ROM at a known address when the chip was burned.

I can think of two or three potential solutions:
1.- Is there a way to gain READ ACCESS to the upper 512k of the 4G address space (0xfff80000-0xffffffff) where the BIOS image is available? (Any attempt to read it directly in assembly language results in a C0000005 access violation, as one would expect.)

2.- Is there a Software Interrupt that will call a subroutine in the bios to return what I want?

3.- Is there a Software Interrupt that will call a user-written subroutine in the bios? (The bios is a custom BCM.)

If none of the above is feasible, can anyone suggest an alternative approach? I would greatly appreciate any suggestions.


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