Missing memory probing

[steveej]

In order to manage the memory, the OS should know how much it has. Extra information about reserved addresses and memory holes (maybe these are the same, I don't know yet), should also be taken into account.

[steveklabnik]

Yup, this is absolutely something that would have to happen for #96 and #81

[dato]

An expedient option would be to get the information from the bootloader. The multiboot specification includes information on how much memory the system has.

This would make the dependency on grub/multiboot a hard one, though; but might be a good start.

[steveklabnik]

@dato big 👍 on that, multiboot should have all the info. I am fine with this.

[steveej]

@dato do you by chance know how this is handled in (U)EFI systems?

[dato]

I’m still using BIOS for my x86_64 OS work, but it’s a similar story as Multiboot: it’s handed to you directly (in this case by EFI firmware), no need to do a special dance with BIOS services and interrupts to get it.

You want, in particular, the GetMemoryMap() service. There is example code in this excellent StackOverflow answer. For those reading along, here’s an overall description.

-d