Comment by gigel82
3 years ago
I'm wondering if you can build an actual "Linux from scratch" with this as the lowest level, without the need to use a host system at all.
3 years ago
I'm wondering if you can build an actual "Linux from scratch" with this as the lowest level, without the need to use a host system at all.
Not using this, but tangentially related is (full disclosure, i am a maintainer of this project) live-bootstrap, which uses about a KB of binary to do a full "Linux from scratch" style thing - read https://github.com/fosslinux/live-bootstrap/blob/master/part... for all 143 steps you have to go through to get there.
Wow, just reading through the list of steps was fascinating!
I can't help but wonder if this is written in x86-16 bit mode to implicitly use Real Mode BIOS functions and platform interfaces as well.
There's something to be said for taking advantage of that existing code; but if that's a dependency it should be part of the environment manifest. Everything has (most things have) a context where it might be useful and that should be included in the explanation so a tool isn't misused and so incorrect expectations aren't set.
It’s written in x86-16 real mode because all immediates are smaller and switching to 32-bit mode takes a fair amount of code.
I would have preferred 32-bit mode because real mode is awkward with its seg:off addressing scheme.
Using the bios functions just allows it to have “not-boring” examples easily.
That's true, but it's still a sort of library dependency. Even for very tiny computers with a lot of hardware assistance, the basic ROM for communicating with the world in a useful way is bigger.
Without structs? Good luck...
LFS already has several "stepping stones" where it walks through a whole set of C compilers from very old ones compiling slightly newer / more capable ones and so on.
Perhaps with a few more "layers of compilers" on top you can get a very early GCC going.
>"Perhaps with a few more "layers of compilers" on top you can get a very early GCC going."
Applause. Best comment ;)
wonder how many extra bytes for structs?
In my experience, probably at least a 200-400 lines of C (another 512 bytes minimum? I don't know the conversion).
The problem is not just declaring structs but accessing them, referencing them, accessing/referencing fields and subfields, etc. That has to all be in the syntax. For such a minimal project you can ignore initialization.
I did all this while adding maybe 500 lines of C to GitHub.com/vitiral/fngi. Never tried for this level of minimalism though.
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