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Topic: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options? (Read 879 times) previous topic - next topic
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Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

The wiki article about full disk encryption says this:
Quote
While booting from your live media, choose From CD/DVD/ISO option regardless of if you are using a CD/DVD or USB. Those who dared to use the forbidden From Stick/HDD option, experienced problems with polkit and other issues, examples of which can be found: here , here , here , etc.
But looking at the boot entries of both options it seems that they are identical? (except for the name, of course)
Also, I don't see how the examples correlate to choosing "From Stick/HDD", since there's no mention of it in the threads themselves.
So, I have two questions:
1. What's the difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?
2. Why is the Stick one so bad?

I've tried searching the forum / wiki / Internet for this, but I couldn't find any related information. (except for this Reddit post, but it's not very helpful)
If I've overlooked something obvious, please let me know and point me to the relevant documentation. :)

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #1 –
none, assuming the UEFI settings are set to boot from the device

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #2 –
Quote from: mrbrklyn – on
none, assuming the UEFI settings are set to boot from the device
Well, then what's the reason for having both, especially if the "From Stick" option can break installs? (or so the wiki says)
I've tried testing on BIOS too, and there doesn't seem to be any difference either. Also, it doesn't look like any other distributions do this (e.g. Debian, Arch, Devuan, Gentoo and Void just have a boot entry with the distro's name)

Sorry, I hope this post doesn't come off as rude, I'm not suggesting that the devs should drop everything and change the boot options immediately, just trying to understand how stuff works here :)

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #3 –
After unpacking the ISO, the only mention of this that I could find is in /boot/grub/kernels.cfg:
Spoiler (click to show/hide)
That's the whole file, and they both load the same stuff? I'm really scratching my head here :(

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #4 –
Quote from: MaxLPM – on
Well, then what's the reason for having both, especially if the "From Stick" option can break installs? (or so the wiki says)
I think the reason for both is there are occasions, I think more with older hardware, where only one would work to boot the iso.
I take with a pinch of salt there is any difference to the resulting installed system. I've never had any issues I'm aware of as far as I know using either method and was unaware until now there was a warning about one of the methods. But I'm basing that only on experience and intuition. I could be wrong.

I suppose you could install both ways to separate partitions and then mount them both and do a recursive diff to see if there are any actual differences.

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #5 –
Quote
I suppose you could install both ways to separate partitions and then mount them both and do a recursive diff to see if there are any actual differences.
Yep, everything's the same except for stuff that's supposed to change (e.g. /etc/shadow, /etc/fstab)
I've tried asking about this in the IRC channel and there are some guesses, though it seems that nobody except for the people that developed the ISO initially (which haven't responded yet) can confirm the actual answer

The closest solution is that it's historical baggage, because looking at a repository from 4 years ago, the difference is in the permissions (rw and ro). But I can't find any mention of this in the ISO, nor can I find the current repository

PS: sorry, kind of necrobumping, but I really think that this situation should be documented

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #6 –
As @gripped said, it's for very old hardware which can't properly boot anything other than ISO.

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #7 –
Well, I guess this can be marked as solved now. Though I'm still interested in the technical standpoint (how exactly is this helping old hardware? Is there an up-to-date repo with the code?)

Re: Difference between the "From CD/DVD/ISO" and "From Stick/HDD" boot options?

Reply #8 –
Quote from: nous – on
As @gripped said, it's for very old hardware which can't properly boot anything other than ISO.


that would be very very old.

I once had an NYLXS installfest where one fellow INSISTED he was going to install  Yggdrasil on a 286.  We kept telling him if can't be done since the kernel was minimum x386 but he wouldn't listen... until his power supply caught fire and killed his machine but good.  This was about 2001.  I'm just glad he didn't burn down our club house.