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I want to change BIOS boot order in my bootsector code. How I can change the boot order of BIOS with assembly programming?

Z.z

Zahra Zamanzadeh
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BIOS is on what is called of ROM-BIOS. ROM means is only readable. So, if you want to change it you need to flash your BIOS but that's not recommended. Also, you can't access like a file and change it like it were somekind of configuration file.

If you want to change boot order in windows go to the msconfig and select the boot order. In linux you can use grub customizer. So, you can't actually program BIOS.

You can access, maybe, on RAM the address where the BIOS reserved address are and then see what is programmed. Once again, you can't just edit it. Maybe you get a ACCESS_VIOLATION error or similar error. see this how BIOS works and see this

It maybe help you a better understanding. :)

EDIT: On this topic maybe you find how to program your BIOS. but you really need to know what are you doing.

Community
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int3
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Look at the "BIOS Boot Specification", however it seem to be impossible to relate the identifiers used in the API with actual devices.

EFI has a proper interface for this.

Timothy Baldwin
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