[jsilence]

Use the same laptop RMS is using and read the source. http://richard.stallman.usesthis.com/

[petsos]

How would I verify that this source was actually used?

[Karunamon]

Build it yourself and verify via hash that what is on the firmware is what would get written.

However, if you're so paranoid that you think this could be a problem, you're already outside the realm of buying preassembled computers anyways. Who knows who could have tampered with it en route?

[JonnieCache]

Build it yourself, using a pencil, paper, and some sort of bit-flipping raygun. You can compile C in your head, right?

[lloeki]

Would not help against Van Eck phreaking and the likes.