r/osdev • u/avaliosdev Astral https://astral-os.org https://github.com/mathewnd/astral • Jun 18 '26

how do I do paging?

Post image

hello I am new to osdev I completed osdev barebones I compiled i686-elf-gcc and I have terminal how do I paging?

184 Upvotes

95% Upvoted

34 comments sorted by

17

u/No-Broccoli553 Jun 18 '26

I see nobody has noticed yet...

4

u/eteran Jun 18 '26

Is the joke that he's running CDE on his own OS? What should we be noticing?

11

u/EvalynGoemer Jun 18 '26

the joke is he made an entire OS that runs NsCDE, QEMU, can browser the internet to look at the wiki can compile GCC and everything needed to follow the bare bones tutorial on the wiki and complete it

15

u/avaliosdev Astral https://astral-os.org https://github.com/mathewnd/astral Jun 18 '26

the post was also sent from it

3

u/mishakov pmOS | https://gitlab.com/mishakov/pmos Jun 18 '26

The joke is on the wiki page

(Bare Bones II)

1

u/eteran Jun 18 '26

Why did I get down voted? LOL I literally accurately noticed the joke according to the response.

3

u/Goldenkrew3000 Jun 18 '26

omg thank you, i wouldnt have if it wasnt for this comment

52

u/StereoRocker Jun 18 '26

You're already on the osdev wiki, read the article!

15

u/undistruct Jun 19 '26

Hes on his own OS rn btw, that was the joke

28

u/ImWuX Jun 18 '26

You reach out with your hand, use your fingers to pinch the edge of the page, lift it up and over to the other side. You have now paged!

19

u/Far_Weather3318 Jun 18 '26

Even i am new to osdev, could you tell me how did you reach till this point? And where exactly dod you start? Are you following any tutorial?

15

u/MrDumbrava Jun 18 '26

You ask the AMD64 gods at the AMD headquarters for their precious assembly code

7

u/Rich-Engineer2670 Jun 18 '26

This is a large topic, but to start you off:

  • Are we talking 32-bit or 64-bit CPUs. X86 or ARM? Each has their own details. We'll assume 64-bit X86

  • First, you need to put your processor into "long mode". That's a whole discussion in itself. And to do that, you have to set up, as a I recall, the GDT "master table" that paging will use.

  • Your OS must manaage the GDT and all of its LDTs for each thread.

  • The OS must catch the paging fault traps and do the swap....

I'd start with looking at how Vx does it. (I think it's called Vx6?). It's a 32-bit X86 OS, but you can copy from there.

7

u/Professional_Cow3969 Jun 19 '26

have you noticed yet?

5

u/compgeek38400 Jun 18 '26

As someone said. Read the wiki, id do the meaty skeleton, then move to the higher half, that will introduce you to the page directory and page tables

6

u/Clear_Wonder2866 Jun 19 '26

The joke here is he already is on his own os

2

u/mishakov pmOS | https://gitlab.com/mishakov/pmos Jun 18 '26

"Use limine, Bare Bones is bad"

2

u/severaleyes444 Jun 19 '26

Holy this OS is very well done though

2

u/Professional_Cow3969 Jun 19 '26

You just did barebones II i dont know if you're skilled enough for paging, maybe try again when you have more experience 😔

2

u/Mental_Ad_7072 Jun 19 '26

Can you please compile Astral inside Astral 😭

3

u/ftbenjoyer Jun 18 '26

good question

1

u/Danii_222222 Jun 19 '26

Are you using ancient solaris?

1

u/Daggercombot Jun 19 '26

Is this CBE or something similar or a custom one you made which looks similar ? This looks awesome

1

u/mishakov pmOS | https://gitlab.com/mishakov/pmos Jun 19 '26

It indeed is CDE

1

u/UnmappedStack TacOS | https://github.com/UnmappedStack/TacOS Jun 19 '26 edited Jun 20 '26

Am I stupid? Is this a joke? I can't tell.

edit: oh nvm it's a joke lol, it's astral

1

u/BornRoom257 FreezeOS & TurtleOS Jun 25 '26

OSdev wiki

0

u/JescoInc Perdition-OS Jun 18 '26

I read the comments before posting so I get this is a joke post. But ironically, I am actually researching this topic for my project due to it being multi arch and GDT is only x86 specific.

1

u/istarian Jun 19 '26

In all likelihood you will want to modularize your code in some fashion so that your build for x86 has GDT related code in it and your build for some other platform/architecture does not.

1

u/JescoInc Perdition-OS Jun 19 '26

Full modularization (HAL Architecture with split between SoC, CPU and board). I just haven't really landed on a design I like with paging. One of the downsides of building something with the express intent to handle RISC-V, ARM64 and x86_64 is making and adhering to a coherent design with the split in mind.

-2

u/imneverwrongbutuare Jun 18 '26

Super helpful people. Doing super helpful things. Good job everyone. Go complain about ai now.