http://www.openbsd.org/faq/faq4.html#Morefdisk
uh-oh! What's our offset? Simple -- the offset of the previous partition plus the size of the partition, in this case, 63+10490382 = 10490445. offset: [0] 10490445 size: [0] * fdisk:*1> in this situation, default offset = 0 ?? may this fuction change to auto caculate the default to 10490445 ? just like offset: [10490445]
