Installing FreeBSD 9.1 amd64 on IBM x3550 M3

[John Alex.]

On 02/12/2013 02:59 AM, kpneal at pobox.com wrote:
> On Mon, Feb 11, 2013 at 11:43:55AM -0800, Kevin Oberman wrote:
>> On Mon, Feb 11, 2013 at 9:58 AM, Panagiotis Christias
>> <p.christias at noc.ntua.gr> wrote:
>>>
>>> I suppose trying an 8.3 installation would be the easiest way to use MBR
>>> instead of GPT, right;
>>
>> That would do it, but 9.1 is perfectly happy doing MBR. It's just not
>> the default.
>>
>> Seems like many BIOSes assume that GPT=uEFI. Clearly this is silly, but...
>>
>> I know Lenovo laptops have this problem and it is VERY annoying. I run
>> FreeBSD on a GPT disk on my ThinkPad, but I have booteasy installed on
>> an MBR disk (which contains W7) and my BIOS is set to boot from that
>> disk.BootEasy then will boot up the GPT disk with FreeBSD.
>
> Doesn't GPT start with an MBR covering the entire disk? How feasible would
> it be to tweak that MBR so that a boot partition was listed in it? Say, a
> partition holding the root filesystem could be listed in both the GPT and
> MBR style. Then a disk could be booted with MBR or GPT at the whim of the
> firmware.
>
> I agree that this BIOS=MBR/UEFI=GPT assumption is pure rubbish. I've got
> machines with this documented restriction and I'd love a way around it.
>

It is feasible, it's known as a hybrid MBR. On Linux I've accomplished 
this using the gdisk utility, I don't know how it can be done on FreeBSD 
though. I had to use this ugly solution in order to install windows 8 on 
a GPT disk on a pc without UEFI support.