Building your own kernel LQ wiki working thread

One thing puzzles me. If encrypted partitions are automatically decrypted at boot, what kind of protection does that offer against theft? Surely it should not be possible to decrypt a stolen laptop without giving some kind of password.

Originally Posted by jsbjsb001 You wouldn't mind incorporating zeebra's example would you Hazel? As I don't want to mess up what you've written in the "making your kernel bootable" section, so I think you could better incorporate that than I could

Done.

Thanks Hazel, perfect

I think now it's just the "Tips and tricks" section to be done, and as far as I'm concerned, the rest of it looks good. I'll add some stuff to the "Tips and tricks" section later on, by which point, I think we'll be able to call it finished.

Originally Posted by hazel One thing puzzles me. If encrypted partitions are automatically decrypted at boot, what kind of protection does that offer against theft? Surely it should not be possible to decrypt a stolen laptop without giving some kind of password.

None as long as the disk is decrypted. Ergo, it makes less sense to encrypt a root partition.
The protection is against theft when the machine is turned off and/or the partition is NOT decrypted (aka active).

Alot of people misunderstand this concept, and think encryption is some magic solution, and seemingly believe that disk encryption works "always" (even when data is decrypted).

One advantage of encrypting personal data partitions is that you can use "autologin" without any risk, as you always need to type the decryption password to be able to use and see content on the encrypted disk. Means people could login with my user with physical access, but they would not be able to see any useful data, it would be like a blank user. I could use both ofcourse, I just don't need it..

I only encrypt my home partition, since you can download everything on my root partition off the internet anyway - and passwords are hashed by default. But I don't have a separate /boot partition though - which was what made me wonder before what the setup is with encrypting the root partition (I get it now though).

Although, we should probably keep the thread on-topic all that said

Yes. Keep up the good work ladies and gentlemen. Keep completing and editing that thing, and it's soon finished.

I am not sure, what are you planning?
I thought this was a how to for build kernel?
I am a little confused, can you explain?

I've reorganized the "installing the kernel" section a bit in relation to installing the kernel, so it's much clearer that there is both the make install way and the way Hazel wrote about, in doing it manually instead. I've also added some sub-sections to the "Tips and tricks" section to deal with the stuff we aren't dealing with in the other sections. I'm still yet to do the "Updating GRUB" sub-section in the "Tips and tricks" section, but hopefully I can do that tonight or tomorrow. In any case, it's very close to being finished AFAICS. So other than maybe some very minor formatting type edits in the other sections, I can't think of any content that should be changed in any way.

Didn't you want to add something about the kernel build system's help system Hazel? As I think that would go quite nicely in the "Tips and tricks" section, and we should have something there about it, even if it's just a quick paragraph or link or whatever.

All that said, if anyone can think of anything we might have missed, now would be a good time to speak up. Thanks.

I've edited your tips and added one of my own. But I think you've gone overboard a bit on "editing GRUB". Most of the options you have put in are not relevant to the subject and will serve only to confuse the novice. I think it would be quite sufficient to have only the essential details (partition to search, required filesystem drivers, gfx mode, location of kernel and initrd, and kernel command line), with a note that further options may be desirable in some cases and a link to the GRUB manual.

Originally Posted by jsbjsb001 I've reorganized the "installing the kernel" section a bit in relation to installing the kernel, so it's much clearer that there is both the make install way and the way Hazel wrote about, in doing it manually instead. I've also added some sub-sections to the "Tips and tricks" section to deal with the stuff we aren't dealing with in the other sections. I'm still yet to do the "Updating GRUB" sub-section in the "Tips and tricks" section, but hopefully I can do that tonight or tomorrow. In any case, it's very close to being finished AFAICS. So other than maybe some very minor formatting type edits in the other sections, I can't think of any content that should be changed in any way. Didn't you want to add something about the kernel build system's help system Hazel? As I think that would go quite nicely in the "Tips and tricks" section, and we should have something there about it, even if it's just a quick paragraph or link or whatever. All that said, if anyone can think of anything we might have missed, now would be a good time to speak up. Thanks.

Why you don't answer me?
I am asking for help because I want to build a kernel.
This is the reason for this topic I think.
But everybody is silent.
jsbjsb001 called me a troll.
Why?
I was following this forum for many years and always his topics are very interesting.
He said he would go away forever, but now he's back.
i was very happy, I made an account.
I even used a username as hommage to jsbjsb001 and because we have the same initials.
Now I get abused.

So if you want to build your own kernel, why don't you go to the wiki article that we have so kindly created for you and follow the instructions?

You can do really useful work here by testing our instructions to see if they are understandable to the naive user and if they actually result in a bootable kernel. And then report back to this thread.

Originally Posted by hazel I've edited your tips and added one of my own. But I think you've gone overboard a bit on "editing GRUB". Most of the options you have put in are not relevant to the subject and will serve only to confuse the novice. I think it would be quite sufficient to have only the essential details (partition to search, required filesystem drivers, gfx mode, location of kernel and initrd, and kernel command line), with a note that further options may be desirable in some cases and a link to the GRUB manual.

Cool, I think that bit about the kernel help is a very good idea, and very helpful. I can see what you mean about the GRUB stuff, so I'll see what I can do about cleaning that bit up. I can do an external link to the GRUB manual, that's no biggie.

I've also tried MediaWiki's version of code tags in the "LLVM/Clang issues" sub-section of the "Tips and tricks" section for the error message you may get about the CONFIG_DEBUG_INFO_BTF kernel config option, but if you don't have newlines between the different lines it puts them all on the same line. I must say that MediaWiki's version of code tags is absolute crap and doesn't look much better than just putting the lines in bold font - so that section is about the best it's going to look.

In any case, once I finish off the last bit yet to be finished in the "Tips and tricks" section, I think we'll be done and the wiki article will be finished.

I've changed the "adding your kernel to the grub boot menu" sub-section in "Tips and tricks" like Hazel said before. I've also done a minor cleanup in the "configuration" section by adding a "Notes" sub-section at the bottom of it, instead of having "Note 1:..." and "Note 2:...". I've also finished the "Updating GRUB" sub-section in "Tips and tricks", and added a sub-section about copying your current kernel config over in "Tips and tricks" since I forgot to do that yesterday.

So I'm thinking that apart from maybe some extremely minor formatting issues, it's looking about finished to me. I think as far as the content we already have there goes, it looks like enough to me, and I can't see anything that should be changed content-wise.

Thoughts?

Originally Posted by hazel I've edited your tips and added one of my own. But I think you've gone overboard a bit on "editing GRUB". Most of the options you have put in are not relevant to the subject and will serve only to confuse the novice. I think it would be quite sufficient to have only the essential details (partition to search, required filesystem drivers, gfx mode, location of kernel and initrd, and kernel command line), with a note that further options may be desirable in some cases and a link to the GRUB manual.

I agree. Often this actually comes down to just using a GUI to automate this step, especially for newbs, and especially with Grub2. But this step is also the most "dangerous" one, it's the one that can actually have you brick your own computer so to say (if you make some critical mistakes). With grub 2 I think the recommended way should be the GUI way, and it should just be mentioned. I also think it should be mentioned how you can do it manually, and that there are other bootloaders as well, and perhaps linking to their manuals, and the Grub 2 tutorial I linked to earlier (as an alternative to the manual).

The risks SHOULD be fairly low, but over the years I've made many bootloader mistakes and ended up in weird situations that I had to fix, or the bootloader did something weird that I had to correct. There are situations where you can end up with troubles, and you have to have the knowledge of how to fix these troubles unless you just want to end in a very frustrating situation. I most of the time enjoyed those situations and found it an interesting learning experience, but it's different for a newbie or someone who just want the newest Nvidia or ATI driver.

Originally Posted by zeebra I agree. Often this actually comes down to just using a GUI to automate this step, especially for newbs, and especially with Grub2.

In the main body of the wiki, under "Making your kernel bootable" I have said that in most cases the GRUB scripts will autodetect your new kernel. All you need to do is run update-grub (or use some gui equivalent to that command). jsb's notes in the Tips and Tricks appendix on how to edit the GRUB scripts by hand are only relevant in the rare cases where autodetection fails.

But this step is also the most "dangerous" one, it's the one that can actually have you brick your own computer so to say (if you make some critical mistakes).

It's not as bad as that! You can brick your computer if you do something silly with the /sys/firmware/efi/vars contents, but mucking up your bootloader only means that you have to boot temporarily from a rescue disc. You can always fix things from there.

There are situations where you can end up with troubles, and you have to have the knowledge of how to fix these troubles unless you just want to end in a very frustrating situation. I most of the time enjoyed those situations and found it an interesting learning experience, but it's different for a newbie or someone who just want the newest Nvidia or ATI driver.

Actually I think it can be a very enlightening experience for a newbie to find out that even this kind of thing can usually be fixed in Linux. The first Linux I ever had was completely unbootable and I didn't have an internet connection so I couldn't go online to ask for help. I had to use a Knoppix disc and a book called "Running Linux" to fix the issues.