pmbr: Boot loader too large

[Daniel Braniss]

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> On Tue, 22 Jan 2013 12:24+0100, Trond Endrest=F8l wrote:
> 
> > On Tue, 22 Jan 2013 13:21+0200, Daniel Braniss wrote:
> >=20
> > > hi,
> > > this is the output from gpart show:
> > > =3D>       34  976773101  ada0  GPT  (465G)
> > >          34       2048     1  freebsd-boot  (1.0M)
> > >        2082    4194304     2  freebsd-ufs  [bootme]  (2.0G)
> > >     4196386   12582912     3  freebsd-swap  (6.0G)
> > >    16779298  959993837     4  freebsd-zfs  (457G)
> > >=20
> > > =3D>       34  976773101  ada1  GPT  (465G)
> > >          34       2048     1  freebsd-boot  (1.0M)
> > >        2082    4194304     2  freebsd-ufs  (2.0G)
> > >     4196386   12582912     3  freebsd-swap  (6.0G)
> > >    16779298  959993837     4  freebsd-zfs  (457G)
> > >=20
> > > I also did:
> > > 	gpart bootcode -b /boot/pmbr ada0
> > >=20
> > > I'm trying to boot and get
> > >   Boot loader too large
> > >=20
> > > not matter if I boot from disk or pxe.
> > > The pmbr is 512 bytes, so what causes it to overshoot?=20
> > > I don't know x86 assembler (nor want to :-), but the comment says:=20
> > > 	545k should be enough
> > > so what's going on?
> > > thanks,
> > > 	danny
> >=20
> > A freebsd-boot partition must never be larger than 128K, i.e. 65536=20
> > 512B blocks.
> 
> I was partially right. Unless=20
> http://www.freebsd.org/doc/handbook/bsdinstall-partitioning.html is=20
> seriously outdated, then the maximum size of an freebsd-boot partition=20
> is 512K, i.e. 262144 512B blocks.
> 
> ``Tip: Proper sector alignment provides the best performance, and=20
> making partition sizes even multiples of 4K bytes helps to ensure=20
> alignment on drives with either 512-byte or 4K-byte sectors.=20
> Generally, using partition sizes that are even multiples of 1M or 1G=20
> is the easiest way to make sure every partition starts at an even=20
> multiple of 4K. One exception: at present, the freebsd-boot partition=20
> should be no larger than 512K due to boot code limitations.''
> 
> Perhaps you should shrink the freebsd-boot partition and possibly=20
> reapply /boot/gptboot.
I did exactly that, and now all is ok.
what got me going in the wrong direction was the message:
	Loader file too large
it's anything but that, it's the partition size! I reduced it to 64k and now all
is ok.

the source pmbr.s seems to say different - 545K, but since gptboot is 15k ...

someone should mention it in the gpart(8) man page.

cheers,
	danny