Systems And Methods Of Secure BIOS Update

A computer-implemented method comprising:

• during a power-on sequence:
• determining a value to be written to a first register in a device, the device generating a signal which controls writes to a reprogrammable memory;
• saving the value to a location accessible in system management mode;
• and
• writing the value to the first register in the device;
• while executing in system management mode:
• retrieving the saved value from the location;
• writing the retrieved value to a second register in the device;
• and
• responsive to writing the retrieved value, writing to the reprogrammable memory.

A system comprising:

• memory having power on code and a system management interrupt handler stored thereon;
• a processor configured by the power on code to:
• determine a value to be written to a first register in a device, the device generating a signal which enables writes to a reprogrammable memory;
• save the value to a location accessible in system management mode;
• and
• write the value to the first register in the device;
• wherein the processor is configured by the system management interrupt handler to:
• retrieve the saved value from the location;
• write the retrieved value to a second register in the device;
• and
• responsive to writing the retrieved value, write to the reprogrammable memory.