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Ask HN: Where can I find a primer on how computers boot?

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Re: Ask HN: Where can I find a primer on how computers boot?

#81

Post by monocasa »

zekica wrote: post #14

Here are a couple of resources I think can help you: - old x86 PCs boot in BIOS mode: https://opensource.com/article/17/2/linux-boot-and-startup With BIOS, your PC initializes hardware and contains firmware drivers for reading disk drives. BIOS loads the first sector (MBR) from the selected boot drive to a fixed memory location and jumps to it. Everything else is up to the bootloader (BIOS still provides methods for…

> other ARM devices and most MIPS, RISC-V commonly use U-Boot with Device Tree (as without UEFI or ACPI, there has to be a way to inform the kernel of basic non-PNP hardware and how to communicate with it).

Additionally, UEFI on ARM (and probably RISC-V) will commonly give you a device tree too. The two aren't mutually exclusive and modern ARM SoCs more or less require kernel space to have more information than UEFI is capable of conveying.

Re: Ask HN: Where can I find a primer on how computers boot?

#83

Post by rnd0 »

klodolph wrote: post #43
junon wrote: post #15

https://osdev.org has a lot of resources about this. Your computer and all of its hardware are built on standards. For the most part, they are adhered to by hardware and BIOS manufacturers. GRUB et al are just abstracting those away because they're obtuse and not very ergonomic to work with from day to day.

I also recommend the OSDev Wiki. It also includes information you’d need to write your own bootloader, if that’s what you want to do.

Isn't a lot of the material there deliberately obscufated and/or wrong but not corrected for the sake of making people figure it out themselves?

Re: Ask HN: Where can I find a primer on how computers boot?

#86

Post by MonaroVXR »

pjc50 wrote: post #53
MuffinFlavored wrote: post #46

Earlier quoted context omitted.

> It’s firmware time. Your machine has a motherboard, there is a chip on it which has had BIOS (Basic Input/Output System) flashed on it. I wonder if it's worth it to call out the "processor microcode" firmware? Any cool startup things happen at that low level as well?

The microcode is mostly irrelevant, and is also opaque. It might be doing something but Intel won't give you more details beyond the programmer's reference model. "Microcode" generally looks more like expanding a CISC instruction into other instructions, rather than something that looks like a program. Extremely low level paper: https://www.researchgate.net/publication/295010710_Booting_a... ; good to confirm that In…

I knew it would boot at 16bit mode, I need to make an article.

Re: Ask HN: Where can I find a primer on how computers boot?

#87

Post by the_panopticon »

sebow wrote: post #68

This thread almost has all the good resources out there, however a good book I haven't seen mentioned is "Hands-on Booting" [ISBN-10: 1484258894]. It does not go into deep technicalities but if you want a good overall picture(how the microsoft bootloader works and how especially grub works) it's definitely beginner-friendly in my opinion.

That's a good book. A few others from Apress include A few books may help include "Building Secure Firmware" https://link.springer.com/book/10.1007/978-1-4842-6106-4 and "System Firmware" https://link.springer.com/book/10.1007/978-1-4842-7939-7. A couple of older items from DeGruyter are "Beyond Bios" https://www.degruyter.com/document/doi/10.1515/9781501505690... and "Quick Boot" https://www.degruyter.com/document/doi/10.1515/9781501506819....

Re: Ask HN: Where can I find a primer on how computers boot?

#88

Post by junon »

rnd0 wrote: post #83
klodolph wrote: post #43

Earlier quoted context omitted.

I also recommend the OSDev Wiki. It also includes information you’d need to write your own bootloader, if that’s what you want to do.

Isn't a lot of the material there deliberately obscufated and/or wrong but not corrected for the sake of making people figure it out themselves?

No lol, where did you get that idea?
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