[Btrfs-devel] Re: BTRFS partition usage...

[Rene Herman]

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