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 Post subject: How can I edit MBR hex code so that grub only boots UEFI.
PostPosted: August 6th, 2020, 4:21 
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Joined: August 6th, 2020, 4:07
Posts: 2
Location: somewhere
I tried looking up some documentation but they are so limited.
It's a really long story why i need this so if anybody knows please help me. Don't ask me why otherwise please.

So this iso boots both UEFI and legacy but i want to destroy its ability to boot BIOS. I burn the iso to HDD btw.

I just need to know how UEFI is different than BIOS in terms of MBR structure.


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 Post subject: Re: How can I edit MBR hex code so that grub only boots UEFI
PostPosted: August 6th, 2020, 17:41 
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Joined: September 8th, 2009, 18:21
Posts: 12750
Location: Australia
UEFI doesn't use the MBR code for booting. Instead it searches for a boot partition. Therefore you should be able to write zeros to the MBR without affecting a normal UEFI bootup. I don't know how GRUB fits in, though.

Someone please correct me if I'm wrong.

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A backup a day keeps DR away.


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 Post subject: Re: How can I edit MBR hex code so that grub only boots UEFI
PostPosted: August 16th, 2020, 6:41 
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Joined: August 6th, 2020, 4:07
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Late thanks, filling with zeroes does work.

dd if=/dev/zero of=/dev/sdX bs=446 count=1

example

dd if=/dev/zero of=/dev/sda bs=446 count=1


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