US 6,308,265 B1 · Protection of boot block code while allowing write accesses to the boot block

Abstract

An apparatus and a method for protecting boot block code while allowing updating to BIOS code during a flash BIOS operation. The boot block code is stored in a boot block or boot region of a flash part, and then a copy of the boot block code is written into another region of the flash part. The image of the boot block code in the another region is compared with the boot block code in the boot block, and if there is a match, the boot block region is unprotected, thereby allowing an update of code in the boot block. The boot block code of the flashed-in BIOS image in the boot block region is compared with the copy of the boot block code in the another region, and if there is a match, the code in the boot block region is protected. If there is not a match or if a power failure occurs, the system is booted up using the boot block code in the another region.

Claims19

Dependent claims

A method of protecting first boot block code and allowing an update to other code or data residing in a same segment or region as the first boot block code, wherein the first boot block code and the other code or data is stored in a first writable segment of a memory that is initially set to a protected non-writable state, the method comprising the steps of:

a) copying all information stored in the first writable segment of the memory into a second writable segment of the memory;
b) validating the copied information in the second writable segment of the memory;
c) setting the first writable segment to a non-protected, writable state;
d) erasing all information stored in the first writable segment;
e) updating the first writable segment with updated code or data, the updated code or data including second boot block code;
f) comparing the second boot block code stored in the first writable segment with the first boot block code stored in the second writable segment;
g) if the comparison in step f) is such that the second and first boot block codes respectively stored in the first and second rewritable segments are identical, setting the first rewritable segment to the protected, non-writable state.

4 more elements

A computer program product, comprising a computer usable medium having computer readable program code embodied therein, the computer readable program code in said computer program product comprising:

a) first computer readable code for copying all code and data stored in a first writable segment of the computer usable medium into a second writable segment of the computer usable medium, the copied code and data including first boot block code;
b) second computer readable code for validating the copied code and data in the second writable segment of the computer usable medium;
c) third computer readable code for setting the first writable segment to a non-protected, writable state;
d) fourth computer readable code for erasing all of the code and data stored in the first writable segment;
e) fifth computer readable code for updating the first writable segment with updated code or data, the updated code or data including second boot block code;
f) sixth computer readable code for comparing the first boot block code stored in the first writable segment with the second boot block code stored in the second writable segment,
wherein, if the comparison by the sixth computer readable code is such that the second and first boot block codes respectively stored in the first and second rewritable segments are identical, setting the first rewritable segment to the protected, non-writable state.

4 more elements

Dependencies are inferred from the claim text.

Protection of boot block code while allowing write accesses to the boot block

Life of this patent

Protection of boot block code while allowing write accesses to the boot block

Life of this patent

Abstract

Claims19