svn commit: r221972 - head/sys/geom/part

[Poul-Henning Kamp]

In message <4DD9F0A3.701 at FreeBSD.org>, "Andrey V. Elsukov" writes:

>There is another opinion:
>http://www.boot-us.com/gloss02.htm
>
>"There is the convention that partitions should always start and end on *=
>cylinder boundaries*."

It is actually more weird than that:

The rule is that the starting or ending head of one of the four
slices represent the number of heads used to access the drive, and
ditto for sectors.

This "requirement" dates back to "smart" BIOS'es and ST-506 drives
which couldn't ask the drive for its geometry.

It has been revived a couple of times, when people got creative
around the various silly sizes, most notably the 524MB "limit".

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phk at FreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained by incompetence.