svn commit: r216269 - head/sys/geom/part

Erik Trulsson ertr1013 at
Fri Dec 10 01:10:50 UTC 2010

On Fri, Dec 10, 2010 at 12:36:57AM +0200, Andriy Gapon wrote:
> on 10/12/2010 00:14 Bruce Cran said the following:
> > Since it appears that disks are still using the CHS fields despite
> > having been obsolete since ATA-7 I guess it makes sense to continue
> > printing them.
> I apologize for repeating myself, that probably starts to be annoying...
> We read some reserved/unused/obsolete bytes and get some garbage in them.
> The fact that the garbage looks like "valid" (for some definition of "valid")
> CHS parameters doesn't mean that those are really valid, or CHS parameters, or
> we should use them, or we should even report them, even for debug.
> That's my personal position and I am sticking to it :-)

No. Those bytes may be obsolete, and might be reserved by the latest
version(s) of the ATA standard, but they are not unused and they do not
contain garbage.  They do contain CHS parameters as set by the drive
manufacturers, and should continue to be reported as such by the tools
we have that provide disk information.

If they should be used for anything other than just listing what the
drive reports is another question, to which the answer is probably no,
since the values reported do not match the actual geometry of the
drives (and haven't done so for many years now.)

<Insert your favourite quote here.>
Erik Trulsson
ertr1013 at

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