Building an OS - 11 - Memory detection

Introduction to the topic of memory management, and detecting memory on the x86 platform.

Links:

Documentation:

Chapters:
0:00 Types of memory
3:40 Memory address space
10:11 Memory management goals
11:17 Memory detection on x86
14:18 Implementing E820 BIOS call
21:57 Implementing main memory detection function
27:25 Modifying main function
28:15 Fixing build process & testing
30:53 Passing memory info to kernel
33:33 Conclusion

[dvdside]

This is criminally underrated! Learnt a ton!

[andrefelipe]

I am a big fan of your channel. It is so nice to see who loves what they do. You are such an inspiration.

[Acesif]

Great content! Never stop making these videos! <3

[windows.]

Wake up babe... nanobyte posted! Keep up :)

[TechTonic]

2:05 inca un roman pe aici. Misto tutoriale, le-am urmat pe toate si am facut si eu un mic OS pe care il bootez de pe USB :)).

[CryptographyForEverybody]

Hiho,
Very nice series. Thx! Watched it this weekend and really enjoyed it so far.
In contrast to the "Write your own Operating System" from Viktor Engelmann, I really like that you also wrote your own boot loader and not rely on the GRUB bootloader.
Also I like that it uses C + ASM. Do you plan to also support C++ in a later stage? What about POSIX compatiblity etc ? 🙂 How far do you plan to go with your OS and this series?
Anyway, thx again for the nice series,
Greetings,
Nils

[willothy]

Great series, definitely one of the most informative I've found on YT. Think you'll cover SMP at some point later on in the series? I haven't found much info on how to actually implement booting multiple cores in a kernel, so it would be super helpful. Thanks!

[frostedson]

Thanks..nano byte..I can’t thank you enough..for this...I’m writing my graduation project and I wanted to write a whole improved kernel from scratch..so I went looking for videos and tutorials in search of where to start from having no knowledge of what I’ve even engaged my self in....I watched a lot but your series gave me the answer of what I actually needed...thanks a lot..
And my question is..what are you going to improve in this is that has maybe been a challenge in the other Os’s?

[rocketnewton]

Respect for including floppy disks in the pyramid 😂

[TanjoGalbi]

Hard drives and SSDs are NOT memory! They are storage devices. The difference is memory, or RAM, is a temporary location for data that can be accessed by the CPU directly for running code, storage media like HDDs, SSDs, Floppies, etc. are for permanent* storage of data but the CPU can not access that data directly thus code can not be run from there. Though technically SSDs and Flash Drives could be called memory because they are made from forms of RAM that can retain the data without power they still fall under the category of storage media because code still can not be run by the CPU directly from them.

* Storage media are supposed to be permanent but we now know nothing truly is, degradation happens! lol

[cxe]

Im using grub with multiboot2 so I only have to read the nessesary data from the mb_info struct provided from grub, right?

[whoknows]

*If you can go over the linux source would be cool*

[LukeNewcomb]

Hey, I love your videos! I was wondering how, not just in this video, but especially in the one about FAT12 where you had the disk cylinders and everything, you make animations/visualizations and just on screen effects and text. What software do you use?

[TanjoGalbi]

You maybe should have created a video for making the change to Scons instead on relying on the livestream to teach us! The livestream is hard to follow when you are also chatting with the chat, it includes mistakes that although do get fixed also make following along difficult to do, plus it's over 4 hours long because of the previous two reasons! It also does not help that in the livestream you have your camera view covering the terminal so the commands you are typing are partially covered!!

I am sure it could be condensed to a 30mins or less video that's easier to follow.

[kamikaze_kev]

let's form a dev team and knock out some hardware drivers for nano's new OS (gpu, sound etc...) exciting!! 🤣😂