On Wed, 21 Sep 2011, Thomas Mueller wrote:
From "Matthew D. Fuller" <fulle...@over-yonder.net>:
I've been meaning to mention this, but we really should document
somewhere that it has a _MAXIMUM_ size.
I setup a system a few weeks back with GPT, and figured I'd just make
the first 'real' partition start at the 1 meg mark. And make
everything before that (1 meg - the however many sectors for the pmbr)
the freebsd-boot partition.
It worked fine, up 'till the point that I tried to boot, and it
completely failed to, complaining that the boot code was too big. I
had to track around in pmbr to find
. . cmp $0x9000,%ax.. . # Don't load past 0x90000,
. . jae err_big.. . # 545k should be enough for
. . mov %ax,%es.. . # any boot code. :)
and redo the partition to 512k (leaving a few hundred k unused before
the next partition started) before it would boot. That's a little
nerve-wracking to hit on a critical system...
I don't think there is any particular advantage in aligning GPT partitions on 1
MB boundaries.
Agreed. But Windows 7 also starts the main partition at 1M. Taking
that as a standard could provide compatibility with other (admittedly
poorly-written) disk partitioning software. And it might not, but if it
helps with POLA for people used to using GPT elsewhere, that's not a bad
reason either.
The bug shown above means the freebsd-boot partition should be limited
to 512K at present. Another 512K of space after that doesn't really
cost anything. If that extra space is needed later, it can be used
without repartitioning.
_______________________________________________
freebsd-current@freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-current
To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
