title: ThinkPad R500 x-toc-enable: true ...
This board as basically identical to the T500, and has very similar disassembly. You must take it apart and flash the chip externally.
The chip is 4MiB NOR flash (SPI protocol) is SOIC8 form factory.
Refer to the following guide:\ Externally rewrite 25xx NOR flash via SPI protocol
Unlike other GM45+ICH9M thinkpads in osboot, the R500 doesn't have an Intel
PHY (for Gigabit Ethernet). However, osboot still includes an Intel flash
descriptor, but with just the descriptor and BIOS region. The ich9gen
program
supports this fully.
Therefore, you do not have to worry about the MAC address. The onboard NIC for ethernet is made by Broadcom (and works in linux-libre).
Refer to T500 disassembly guide. The R500 disassembly procedure is almost identical.