Installing amd64 FreeBSD 11.1 in dual-boot with Windows 7 on an MBR partitioned disk

[Karl Denninger]

On 10/6/2017 10:42, Karl Denninger wrote:
> On 10/6/2017 10:17, Rostislav Krasny wrote:
>> Hi there,
>>
>> I try to install amd64 FreeBSD 11.1 in dual-boot with Windows 7 on an
>> MBR partitioned disk and I can't make it bootable. My Windows 7 uses
>> its standard MBR partitioning scheme (1. 100MB System Reserved
>> Partition; 2 - 127GB disk C partition) and there is about 112GB of
>> free unallocated disk space that I want to use to install FreeBSD on
>> it. As an installation media I use the
>> FreeBSD-11.1-RELEASE-amd64-mini-memstick.img flashed on a USB drive.
>>
>> During the installation, if I choose to use Guided Partitioning Tool
>> and automatic partitioning of the free space, I get a pop-up message
>> that says:
>>
>> ======
>> The existing partition scheme on this disk
>> (MBR) is not bootable on this platform. To
>> install FreeBSD, it must be repartitioned.
>> This will destroy all data on the disk.
>> Are you sure you want to proceed?
>>               [Yes]          [No]
>> ======
>>
>> If instead of the Guided Partitioning Tool I choose to partition the
>> disk manually I get a similar message as a warning and the
>> installation process continues without an error, but the installed
>> FreeBSD system is not bootable. Installing boot0 manually (boot0cfg
>> -Bv /dev/ada0) doesn't fix it. The boot0 boot loader is able to boot
>> Windows but it's unable to start the FreeBSD boot process. It only
>> prints hash symbols when I press F3 (the FreeBSD slice/MBR partition
>> number).
>>
>> I consider this as a critical bug. But maybe there is some workaround
>> that allows me to install the FreeBSD 11.1 as a second OS without
>> repartitioning the entire disk?
>>
>> My hardware is an Intel Core i7 4790 3.6GHz based machine with 16GB
>> RAM. The ada0 disk is 238GB SanDisk SD8SBAT256G1122 (SSD).
>>
> You have to do the partitioning and then install FreeBSD's boot
> manager by hand.  It /does /work; I ran into the same thing with my
> Lenovo X220 and was able to manually install it, which works fine to
> dual-boot between Windows and FreeBSD-11.  I had to do it manually
> because the installer detected that the X220 was UEFI capable and
> insisted on GPT-partitioning the disk, which is incompatible with
> dual-boot and the existing MBR-partitioned Windows installation.
>
> You want the partition layout to look like this:
>
> $ gpart show
> =>       63  500118129  ada0  MBR  (238G)
>          63    4208967     1  ntfs  (2.0G)
>     4209030  307481727     2  ntfs  (147G)
>   311690757          3        - free -  (1.5K)
>   311690760  165675008     3  freebsd  [active]  (79G)
>   477365768     808957        - free -  (395M)
>   478174725   21928725     4  ntfs  (10G)
>   500103450      14742        - free -  (7.2M)
>
> =>        0  165675008  ada0s3  BSD  (79G)
>           0    8388608       1  freebsd-ufs  (4.0G)
>     8388608  136314880       2  freebsd-ufs  (65G)
>   144703488   20971519       4  freebsd-swap  (10G)
>   165675007          1          - free -  (512B)
>
> MBR has only four partitions; the "standard" Windows (7+) install uses
> /three. /The "boot"/repair area, the main partition and, on most
> machines, a "recovery" partition.  That usually leaves partition 3
> free which is where I stuck FreeBSD.   Note that you must then set up
> slices on Partition 3 (e.g. root/usr/swap) as usual.
>
BTW if you're getting the "#" when you hit the partition key that means
the /second stage /boot loader is /not /on the partition you selected;
the bootmanager can't find it.  This can be manually installed with:

# gpart bootcode -b /boot/boot ada0s3

"s3" is the partition in question upon which you created the BSD-labeled
structure.

One thing to be aware of is that you must adjust Windows group policy if
you intend to use Bitlocker, or it will declare the disk structure
changed and refuse to take your key (demanding the recovery key)
whenever the FreeBSD boot manager changes the active "next boot" flag. 
By default /any /change in the boot structure will set off Bitlocker;
you can relax it to not get so cranked, but you need to do so /before
/encrypting the partition under Windows.

I run GELI encryption on the FreeBSD partition which is why I have a
separate (small) boot filesystem; that too has to be manually set up for
an installation like this using MBR.  It works well.

-- 
Karl Denninger
karl at denninger.net <mailto:karl at denninger.net>
/The Market Ticker/
/[S/MIME encrypted email preferred]/
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