Whole disk ZFS or -a4k partition

[Jeremy Chadwick]

On Wed, Jul 03, 2013 at 02:20:04PM -0600, Warren Block wrote:
> On Wed, 3 Jul 2013, Jeremy Chadwick wrote:
> >On Wed, Jul 03, 2013 at 04:16:06PM +0300, Alexandr wrote:
> >>>
> >>Thank you for your explain. I'll try it soon and post my results. One
> >>thing - I can't use gpt-disks because off my laptop's bios (Lenovo
> >>Thinkpad E530) cannot boot it, only mbr-style.
> >
> >You can use GPT with a BIOS that only supports MBR (in other words, you
> >do not need UEFI to boot from GPT).  FreeBSD's boot blocks are
> >intelligent in this regard.
> 
> Yes.  However, the Thinkpad BIOS is not intelligent about GPT:
> http://forums.freebsd.org/showthread.php?t=26759&highlight=UEFI+GPT
> http://www.dec.sakura.ne.jp/~junchoon/machine/freebsd-e.html

Cute.  I like how the user expected Lenovo to respond on a web forum;
nope, not going to happen.  Phone calls + Email work better.

And like many discussions about problems on forums, this one fell into
the abyss.  I couldn't find a PR for this T420 issue (searched PRs
single and multi line text fields for T420).  The patch on Junchoon's
page even says: "I'm pleased if someone takes over above and send-pr",
yet no one did.  *I'm* not going to, because I don't have a T420 to
test patches on.

The only patch relevant is the one listed first, i.e. "Fixes for
9-STABLE after r243243".  The other disk-related ones are irrelevant at
this point.  (I'm intentionally avoiding the ACPI stuff listed, since
we're focused on GPT/PMBR bits in this convo.)

I did verify that as stable/9 r252602 the 0xef Protected MBR workarounds
for the T420 were not present.  So simply put someone needs to step up
to the plate who has this hardware and can verify the
sys/boot/common/part.c workaround works for them.

If someone needs a "more thorough patch" (a single patch that includes
the part.c and diskmbr.h modifications (latter needed since "magic
values" are legitimately shunned)), I can do that, but like I said,
can't test it.

-- 
| Jeremy Chadwick                                   jdc at koitsu.org |
| UNIX Systems Administrator                http://jdc.koitsu.org/ |
| Making life hard for others since 1977.             PGP 4BD6C0CB |