[SOLVED] Partition type UUID for LUKS encrypted RootFS

[nagmat84]

I want a LUKS-encrypted RootFS and I am following Gentoo Wiki: RootFS Encryption. I am partioning my disk with gdisk and I am wondering which of the following partitions types is more appropriate:

• Linux x86-64 root (/), Gdisk code 8304, UUID 4F68BCE3-E8CD-4DB1-96E7-FBCAF984B709
  
• Linux LUKS, Gdisk code 8309, UUID CA7D7CCB-63ED-4C53-861C-1742536059CC

According to the Wiki guide it seems to be 8304. But this leaves the question when should 8309 be used?

[Hu]

What tools will you be using that read and respect the type code? If this is only for display to humans, then likely you are the only one who will ever see it, so you can pick whatever you like. Personally, I would go with 8309 on the basis that I interpret 8304 to be an unencrypted and directly usable root partition. A root partition wrapped in LUKS is not directly usable; it must first be unlocked, and the resulting mapper device is a usable root filesystem.

[nagmat84]

I am using the normal Gentoo tools, nothing unusual. rEFInd as my boot manager, SystemD as my init system, Dracut to build initramfs, etc. I don't know if any of those tools actually use the partition type UUID for some auto-mapping or similar magic stuff. That is part of the question.

If you say that none of those tools actually evaluate the partition type UUID, I probably go with "Linux LUKS" as you suggested.

[Hu]

I am not aware of any of those tools using the partition type field. I doubt systemd would need to care, since it only runs after you boot. I could believe rEFInd or dracut inspecting it to automate informing the kernel of the root partition, but if they do, they likely would expect that the partition is directly usable as a root filesystem. When it has LUKS wrapping, it is not directly usable, so even if they do inspect it, they would likely be misled by giving it type 8304.

[nagmat84]

I correct my previous answer. Linux x86-64 root (/) (Gdisk type code 8304) is the correct partition type even for LUKS encrypted partitions. The same Wiki article Gentoo Wiki: RootFS Encryption states