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Date: Sun, 25 Jan 2015 21:57:49 -0800
From: perryh@pluto.rain.com (Perry Hutchison)
To: andrnils@gmail.com
Subject: How to read a disklabel (Re: What replaces DIOCGDINFO?)
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Andreas Nilsson <andrnils@gmail.com> wrote:
> On Sun, Jan 25, 2015 at 9:31 AM, Perry Hutchison <perryh@pluto.rain.com>
> wrote:
> > -r276737 removed 4 ioctls, including DIOCGDINFO, from <sys/disklabel.h>.
> > The commit log entry says only "Remove old ioctl use and support, once
> > and for all."
> >
> > What are users of that mechanism supposed to use instead?
>
> http://lists.freebsd.org/pipermail/freebsd-current/2015-January/053960.html
> might have the answer for you.

Same symptom, but DIOCGMEDIASIZE is not the solution in this case
because the port reads the disklabel to identify the partition that
contains a particular sector of the device.  To do that, AFAIK it
needs to actually retrieve and examine the label.  The other ioctls
in <sys/disk.h> don't look all that promising, either.