A gpart(8) mystery on 10.3-RELEASE

[Trond Endrestøl]

On Tue, 5 Apr 2016 15:34+0300, Boris Samorodov wrote:

> 05.04.16 12:30, Trond Endrestøl пишет:
> 
> > What am I doing wrong? Can't gpart(8) write both the pmbr and the efi 
> > image as a single command? Is it an off-by-one error in gpart(8)?
> 
> Should it?

Yes, then it would complement the BIOS style invocation:

gpart bootcode -b /boot/pmbr -p /boot/gptzfsboot -i 1 ada0

> > uname -a
> > FreeBSD  10.3-RELEASE FreeBSD 10.3-RELEASE #0 r297264: Fri Mar 25 02:10:02 UTC 2016     root at releng1.nyi.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64
> > 
> > gpart create -s gpt ada0
> > ada0 created
> > 
> > gpart add -a 4K -s 800K -t efi ada0
> > ada0p1 added
> > 
> > gpart add -a 4K -s 4G -t freebsd-swap ada0
> > ada0p2 added
> > 
> > gpart add -a 4K -t freebsd-zfs ada0
> > ada0p3 added
> > 
> > gpart show -p ada0
> > =>      34  41942973    ada0  GPT  (20G)
> >         34         6          - free -  (3.0K)
> >         40      1600  ada0p1  efi  (800K)
> >       1640   8388608  ada0p2  freebsd-swap  (4.0G)
> >    8390248  33552752  ada0p3  freebsd-zfs  (16G)
> >   41943000         7          - free -  (3.5K)
> > 
> > gpart bootcode -b /boot/pmbr -p /boot/boot1.efifat -i 1 ada0
> > gpart: /boot/boot1.efifat: file too big (524288 limit)
> 
> Do you try to get only UEFI boot? Then do not use "-b" option. It is
> needed for BIOS boot.

UEFI and GPT specify the PMBR as a way of telling legacy software not 
to meddle with the (P)MBR. I wouldn't expect a new disk to contain 
anything in disk block 0, thus the (misguided on my part?) need for 
initializing block 0 as a proper PMBR.

> Do you need to get a system with both UEFI and BIOS boot? Then use two
> different partitions for UEFI and BIOS booting schemes.

I have no need for dual-booting.

> > gpart bootcode -b /boot/pmbr ada0
> > bootcode written to ada0
> 
> This is needed only for BIOS boot and together with "-p /boot/gptboot"
> option.
> 
> > gpart bootcode -p /boot/boot1.efifat -i 1 ada0
> > <no output>
> 
> Hm, I'm not sure if this is supposed (like: supported) to be done like
> this. One may use dd to copy this partition image (boot1.efifat) if
> target partition is not less then the file length.
> 
> Otherwise one may format the target efi partition as an msdos-fat one,
> create /EFI/BOOT mountpoint and copy boot64x.efi file there.
> 
> Here is a link from another similar thead:
> http://www.wonkity.com/~wblock/docs/html/disksetup.html#_booting_with_uefi
> 
> > System is bootable.

I guess I upset you all. Case closed.

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| Trond Endrestøl,              | Trond Endrestøl,                   |
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