svn commit: r264907 - in head/release: amd64 i386

[Don Lewis]

On 24 Apr, Glen Barber wrote:
> On Thu, Apr 24, 2014 at 07:12:10PM -0700, Nathan Whitehorn wrote:
>> On 04/24/14 18:38, Glen Barber wrote:
>> >Author: gjb
>> >Date: Fri Apr 25 01:38:57 2014
>> >New Revision: 264907
>> >URL: http://svnweb.freebsd.org/changeset/base/264907
>> >
>> >Log:
>> >   Refactor make-memstick.sh to avoid creating the 'dangerously
>> >   dedicated' partition scheme, reported to cause the memstick.img
>> >   to fail to boot.
>> >   Similar to how make-memstick.sh worked on stable/8, use makefs(8)
>> >   to create the actual filesystem.  Then calculate the size of the
>> >   resulting image file, create the GPT partition scheme, then dd(1)
>> >   the filesystem created with makefs(8) to the freebsd-ufs GPT
>> >   partition.
>> >   This was tested on a known-working machine[1] for regression, and
>> >   a known-not-working machine[2] to ensure the boot issue has been
>> >   resolved.
>> >
>> 
>> GPT may not be the best choice here. On a number of, in particular, Lenovo
>> hardware, the BIOS will unconditionally boot with EFI from GPT media. I'm
>> not sure we want to just swap the set of machines on which this will not
>> boot. It probably needs to be nested MBR (or straight MBR -- I forget if
>> that works) until the boot media work with EFI (which should be soon on
>> -CURRENT).
> 
> Noted.  The thing here is that I want to get an EFI GPT partition on the
> image eventually, which unless I'm missing something obvious, we cannot
> mix GPT and MBR.
> 
> I don't particularly like swapping which machines boot with this hack.
> Maybe it's time to do a MBR stick for "legacy" boot, and the GPT stick
> for UEFI and/or "fails-to-boot-DD" case?

I've got a fairly recent Gigabyte motherboard that refused to boot an
Ultimate Boot CD memstick which uses MBR.  I found out that I was was
able to boot and install from a 'dangerously dedicated' FreeBSD 9.x
memstick. Given that clue, I built a 'dangerously dedicated' Ultimate
Boot CD memstick, which worked just fine.