Lenovo T420 installlation with zfsroot and GPT/UEFI (FreeBSD 10.1)

Niklaas Baudet von Gersdorff niklaas at kulturflatrate.net
Wed Apr 22 07:05:49 UTC 2015


I'd like to install FreeBSD 10.1 on my a bit old but working Lenovo
Thinkpad T420. In the ideal case I am able to install it with an
encrypted ZFS root and GPT/UEFI. The problem I encountered indicate that
this might not be possible though.

What I did is the following: I downloaded the *uefi-memstick*.img, dd-ed
it on a flash disk and proceeded with the installation. Once I selected
the guided installation with ZFS as root, I get a warning stating that
UEFI is not possible. Hence, I should make sure to boot in legacy. That
is no problem because I set legacy and UEFI to boot in the BIOS. I

The installation works fine. Nonetheless, the system is not able to boot
and continues presenting me a dialogue which asks me to select the boot
device. This problem is quite known: It's a bug in the BIOS of the T420
that prevents booting from GPT partitions.

The bug itself is shortly described at


where one can also find a solution. It says:


    The trick is to add an empty but "active" "partition 1", which must
    have type 0x00, and move the partition of type 0xee (i.e., GPT) to
    partition 2.


Unfortunately, the final step

    fdisk -f /tmp/part $disk

does not work because the prompt claims that the number of cylinders I
entered is to high:

    fdisk: WARNING line 2: number of cylinders (31257387) may be
    out-of-range (must be within 1-1024 for normal BIOS operation unless
    the entire disk is dedicated to FreeBSD)

My modified entry reads as follows:
    # /dev/ada0
    g c31257387 h16 s1
    p 0x00 1 500118191
    a 1
    p 0xee 1 500118191

What am I doing wrong? Or is there another way of getting the desired
set-up to work?

Any help is very much appreciated,



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