[Date Prev][Date Next] [Thread Prev][Thread Next] [Date Index] [Thread Index]

Re: GRUB problem

On Tue, 27 Sep 2005, Jeremy Merritt wrote:

> If having multiple partitions is the problem or part
> of the problem,

NOT the problem

> how do I make /dev/hda2 bootable and
> make the others not bootable?

take it out with the bios so that it doesn't check it

	# delete the MBR on the whole disk
	dd if=/dev/zero of=/dev/hda bs=446 count=1

	# delete the MBR on partition1
	dd if=/dev/zero of=/dev/hda1 bs=446 count=1

	# delete the MBR on partition2
	dd if=/dev/zero of=/dev/hda2 bs=446 count=1

	but do NOT do "dd" if you donno what you're doing
	and the consequence ( you WILL lose data )

> Is that the only thing
> that needs to be done in addition to the other steps?

a partition or disk is bootable when:

   a) you explicitly tell lilo or grub

	boot=/dev/hda2	- the mbr of just this partition
	boot=/dev/hda	- the mbr of the whole thingie
   b) you do tell the bios with:
	fdisk> a 2	- set the bootable flag on partition2

      you can check bytes 511 and 512 of track-0, head-0, sector-0
	( aka the MBR of the disk )

      	same for the mbr of the partition... but starting at
	whever you started the partition at

nowdays, the bios and bootloaders try to be smarter and doesn't
care if the bootable flag is set or not

if you tell it it's bootable and there's nothing to boot
and you only have 1 bootable media ( anything you can boot from ),
you will get "no operating sysstem found"

c ya

Reply to: