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failed to boot both default and fallback entries.

this is the error I get when I try to boot my OS with qemu, OR virtualbox. I compiled many times in different ways configured some settings a bunch of times and nothing worked. All the time the same error.

Well that's too bad. Thanks for sharing.

kzinti wrote:Well that's too bad. Thanks for sharing.

not helping.

FIXED FINALLY

edit - reason is because the RAM was too less which i did not realize the OS needed like 1 GiB and i put 264 megabytes

thewebparadox wrote:not helping.

There wasn't anything in your post to help you with.

Hi,


Assuming you just started out (otherwise you would had already some previous build that worked), having a requirement of 1 GiB is definitely too much. I suggest you look into it. Are you sure your code is loaded at the address you expect it (usually 0x00100000)? Even if built with the most "unoptimised for size" options, a Bare Bones kernel should be way less than 100 KiB, let alone 1 GiB.


Regards,
glauxosdever

It's good when an error message tells you exactly what the problem is.

Have to agree with glaux, I think there is something more to this. I assume the out of memory error was from Grub? If you posted your code (on github or some other service) to this point we could take a look. I have a suspicion you are masking another problem by changing memory size.

I am curious if you are doing the higher half kernel?

Hi,

My best guess (given that I don't have Combuster's famous crystal ball...) is that one of two things is happening:

1. You have a lower half stub and higher half kernel in the same flat binary and your linker has kindly padded the kernel out to a multi-GiB file. In this case switch to ELF.
2. You have linked the higher-half kernel to some high memory address and the linker is attempting to place your kernel at that physical location. In this case, make use of proper linker directives to separate your kernel's physical and linear addresses.

Cheers,
Adam