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Novena has the bottom-up approach of Bunnie saying "oh here's a cool chip. I'll build something around it and see how complete it will be in the end."Purism see
by hengheng 12y ago
Novena has the bottom-up approach of Bunnie saying "oh here's a cool chip. I'll build something around it and see how complete it will be in the end."Purism seems to say "Let's make a machine that lives up to everyone's expectation, and let's try and remove all closed source blobs from it". They are going the top-down way of stripping an X86 machine from all its secret firmware.
I doubt they'll be as successful as Bunnie was with his approach when it comes to making a "clean" device with no dark and shady corners. (Or for that matter, even as clean as the Coreboot X60.) In turn, the Purism device feels a lot more desirable to me. Let's see if they can make it happen.
- cbd1984 12y ago> They are going the top-down way of stripping an X86 machine from all its secret firmware. Do they consider CPU microcode updates to be secret firmware?
- belorn 12y agoI am not a CPU designer, so could someone explain the threat model of cpu microcode? Is it plausible that you could fit memory scraping code, including code that interacts with OS network drivers, all inside the cpu microcode without causing catastrophically impact on performance?
- sp332 12y agoSure. The TPM is connected via a bus, but there's no reason you couldn't build something like it into any other chip, including the CPU itself. http://en.wikipedia.org/wiki/Trusted_Platform_Module http://en.wikipedia.org/wiki/Trusted_Platform_Module
- michaelt 12y agoYou don't need to - all you need is code that says if you're processing data and you see this special sequence of bytes, start executing whatever follows it as kernel-level code. This would be comparatively simple - you're just looking for a sequence of bytes and, if you see it, updating one or two registers. Then you just need to get the special sequence followed by your exploit into the target's memory, which is trivial. Send them an e-mail, embed it in a picture of a cat and post it to reddit, stick it on the end of a gif in a banner ad, whatever. If you check for the special sequence on the fast side of a fast/slow interface (like the interface between RAM and on-die cache) the speed impact would be all but invisible.
- comex 12y agoIn addition to michaelt's comment, it's worth noting that security issues are only one of many reasons to prefer free software - at least in the opinion of the GNU crowd they are appealing to.
- dmm 12y agoThe CPU is fused to accept non-signed microcode so someone could eventually replace the microcode with a free alternative.
- deleted 12y ago[deleted]
- comex 12y agoIt's fused to accept a non-signed BIOS. Microcode is separate and, considering how tight-lipped Intel is about it, almost certainly won't be customizable in the foreseeable future. (Unfortunately.)
- yuhong 12y agoMy feeling is that you are already executing CPU microcode on reset anyway.