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tboot in Fedora 19: Don’t worry, it’s just a bug

After installing Fedora 19 beta and rebooting my test computer, I noticed that one of the options available in GRUB’s menu is tboot 1.7.0. Not sure what it’s for, I selected it and hit the Enter key.
Fedora 19 tBoot Trusted boot Intel TXT

On the next GRUB screen, is the option to boot into Fedora GNU/Linux, with tboot 1.7.0. But what does tboot do? Well, one way to find out is to boot into the system and see what dmesg can tell me. Nothing.
Fedora 19 tBoot Trusted boot Intel TXT

Fedora’s official page on tboot has very little useful information, but a search of Apper, the graphical package manager, returns an entry for a tboot package. The description for tboot goes like this:

Trusted Boot (tboot) is an open source, pre-kernel/VMM module that uses Intel Trusted Execution Technology (Intel TXT) to perform a measured and verified launch of an OS kernel/VMM.

Ok, so tboot is the open source package for taking advantage of Intel Trusted Execution Technology (Intel TXT). Intel TXT requires a software and hardware component to work. Here, the software component is obviously tboot. The hardware component is a chip on the motherboard called the Trusted Platform Module (TPM). So if our computer does not have a TPM chip, tboot is of no use to you.

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TPM chips are embedded in the hardware of Intel processors. But most of those are server processors, such as the Intel Xeon E3 v3, Intel Xeon E5 and Intel Xeon E7, and the latest Intel Core vPro processors.

Still not sure what to make of tboot in Fedora 19 beta, I sent an email to Adam Williamson, a Red Hat dude and publisher of happyassassin.net. His reply copied another Red Hat dude who said that tboot appearing by default in GRUB’s menu is a bug, and gave the following reasons why it should not be in the default installation.

1. We don’t really have the infrastructure for doing useful things with it, so it’s really mostly just something an interested party could do development on.

2. Sinit (the method for entering TXT mode) runs a pile of closed source code provided by the firmware on the host CPU effectively as the kernel, and a lot of people aren’t too keen on that. This is especially true since the code is doing things like turning on special processor modes and doing cryptographic verification, which is exactly the sort of thing open review of code often finds tons of bugs in…

3. There are some cases right now where it doesn’t really work right (for instance, UEFI). Obviously these are just bugs, so this is the least important of this list.

So, if you have installed Fedora 19 beta and were/are wondering what the heck that tboot entry in the boot menu is for, don’t worry about it. It’s just a bug. It will not show up in Fedora 19 final.

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Here’s an introductory video about Intel Trusted Execution Technology.

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