Re: BTRFS partition usage...

From: Rene Herman
Date: Tue Feb 12 2008 - 20:21:21 EST


On 13-02-08 00:42, Jan Engelhardt wrote:

x86 MSDOS partition table layout starts counting with sector 1, which is
(not so intuitively) starting at 0x7e00 (and there's no sector 0, probably for safety). Well, each ptable format with its own quirks.

I haven't followed this thread, but in case it matters -- this sounds fairly confused.

Not sure what you're saying, but the MSDOS partition table has its root table in the very first sector on the disk, at offset 0x1be = 0x200 - 4 * sizeof(struct partition) - 2 (that is, 4 entries at the end of that first sector, followed by a 2-byte signature).

That 0x7e00 that you are speaking of sounds somewhat like the _memory_ address the BIOS loads that first sector to: 0x7c00. It then jumps there to start the ball rolling but 0x7c00 is not an on-disk reality or anything.

MS-DOS partition tables are furthermore fully outside the actual partitions themselves and as such I believe not all together relevant to the issue? (as said, not following along though...)

Rene
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