Date: Fri, 06 Feb 98 15:23:00 -0000 From: mikebw@bilow.bilow.uu.ids.net (Mike Bilow) To: aic7xxx@FreeBSD.ORG Subject: Partition boundary (was: Extended BIOS translation (worth disabling?)) Message-ID: <4db2a313@bilow.bilow.uu.ids.net>
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Peter Holzer wrote in a message to Mike Bilow: PH> The BIOS handles arbitrary partition boundaries fine (all it PH> gets are "read n sectors starting at cyl a, head b, sector PH> c" requests. It doesn't even know about partitions). MS-DOS PH> doesn't, but AFAIR it starts partitions on head 1 (instead PH> head 0) of a cylinder, so either Linux fdisk cannot create PH> DOS compatible partitions or it already has some special PH> code for them. PH> Looking at the partition table of my disk, it looks like PH> fdisk puts the start of the first partition and all the PH> logical partitions at head 1: The MS-DOS rule is actually very simple: 1. If the first sector of the cylinder (under head 0) contains a partition table, either the primary table or any extended table, then do not allocate the rest of the track. The next allocable area of the disk is the first sector under the next head (1) on the same cylinder. 2. If the first sector of the cylinder (under head 0) does not contain a partition table, then that sector is allocated as the start of the partition. -- Mike
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