After creating an image file with :

dd

disk/mbr

disk/fdisk

disk/prep

the resulting partition table in the mbr  is buggy :

the chs values in the mbr are incompatible with bios.

bios uses the formula (c*H+h)*S+s-1 to calculate the lba values with H=256, S=63 while c (cylinder), h(head), s(sector) are the values from chs entries in the mbr partition table.

disk/fdisk uses the same formula while setting H=64, S=32.

If you write this image to real Hardware (HDD, USB-Sticks) some bios won't boot from such media especially if your boot drive has a size less than 8GB cause for media with sizes less than this size some bios'es use CHS addressing and some verify that sector id's from chs and lba are equal.

9fans / 9fans / see discussions + participants + delivery options Permalink