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 Post subject: use GRUB to boot
PostPosted: Sun Oct 20, 2019 11:20 am 
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Joined: Mon Mar 14, 2016 5:34 am
Posts: 19
i want to test my hobby os with Grub. to boot , i have to copy a file at a specific adress and jump to it in real mode but i dont find the right way to do it with grub. is it possible? and how can i do?
for now i use the nework booting (PXE) and it work fine


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 Post subject: Re: use GRUB to boot
PostPosted: Sun Oct 20, 2019 11:51 am 
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Joined: Mon Mar 25, 2013 7:01 pm
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nlg wrote:
is it possible?

No. GRUB can only boot your OS in protected mode, not real mode.

If you would like to modify your OS so GRUB can load it, you'll need to look at the multiboot specification.


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 Post subject: Re: use GRUB to boot
PostPosted: Sun Oct 20, 2019 12:57 pm 
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i found the command "chainloader" to load file, i dont found any information where the file is exacly loaded but it seem to be used in Dos or Windows booting so i think the file is loaded in the adress 7C00h and the command "boot" jump to it
if the command work like i this, it was perfect function for me, now i have to install grub on a usb key to test it


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 Post subject: Re: use GRUB to boot
PostPosted: Sun Oct 20, 2019 1:37 pm 
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Location: Chichester, UK
You can use chainloader to boot DOS from grub, but it chains to another boot loader. Unless you want to boot multiple operating systems, that rather defeats the purpose of using grub.

https://www.gnu.org/software/grub/manua ... 02dloading


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 Post subject: Re: use GRUB to boot
PostPosted: Sun Oct 20, 2019 4:26 pm 
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Joined: Mon Mar 14, 2016 5:34 am
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alas for me, chainloader only loads the 512 first byte of the file (i test it)

my home bootloader loads an image from a partition and I hope to replace it with grub. at least I can multiboot with my OS even if I still have to sacrifice a MBR partition for that (or I can try to make my kernel multiboot compatible)

thank you all for your indication, it helped me a lot


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