bootloader how to change to boot from cdrom?

[oohayulin]

bootloader how to change to boot from cdrom?

If a bootloader in harddisk, when it boot, how to let it boot from cdrom?

Dont need to load driver, parse filesystem, just to boot from cdrom.

just like chainloader in grub.

[cr2]

bootloader how to change to boot from cdrom?

If a bootloader in harddisk, when it boot, how to let it boot from cdrom?

Dont need to load driver, parse filesystem, just to boot from cdrom.

just like chainloader in grub.

I can barely understand you. Is English your first language or not?

If your bootloader is not a harddisk, I believe you just run the bootsector on the CD-ROM to have it boot.

Dont need to load driver, parse filesystem, just to boot from cdrom.

Yes...you...do...need...a...driver...to...boot...from...CD-ROM...
...but you don't need to parse the filesystem (if I am correct...)

[oohayulin]

my usecase:

When I boot from harddisk with this "bootloader", it will check the cdrom whether it is the "OUR PRODUCT CD", if it is, this "bootloader" will change to boot from cdrom.

So in this way our product dont need the user to modify the Boot Device Order in BIOS. It is our target.

[cr2]

post your code.

So in this way our product dont need the user to modify the Boot Device Order in BIOS. It is our target.

What if your hard disk's bootsector gets corrupted? How will the user access his computer?

Yep. You still need the boot device order.

[oohayulin]

post your code.

So in this way our product dont need the user to modify the Boot Device Order in BIOS. It is our target.

What if your hard disk's bootsector gets corrupted? How will the user access his computer?

Yep. You still need the boot device order.

You are right.
But we just need this bootloader once in this reboot session.
When we finish the function on CDROM, we will restore the mbr.