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Date:      Fri, 1 May 2020 09:34:30 -0600
From:      Warner Losh <imp@bsdimp.com>
To:        Daniel Braniss <danny@cs.huji.ac.il>
Cc:        =?UTF-8?Q?Trond_Endrest=C3=B8l?= <trond.endrestol@ximalas.info>,  "freebsd-hackers@freebsd.org" <hackers@freebsd.org>
Subject:   Re: efi boot question
Message-ID:  <CANCZdfr%2BXM0wF7MyzP5o%2BOSjNvCwrLgq0EjDusGe2%2BTFqdhUpQ@mail.gmail.com>
In-Reply-To: <9FAAF98B-77D1-4D39-8E8E-D20F2B4C2E5C@cs.huji.ac.il>
References:  <8B798F61-783C-4A1C-AEED-4B42E88E5010@cs.huji.ac.il> <alpine.BSF.2.22.395.2005011028470.91211@enterprise.ximalas.info> <9FAAF98B-77D1-4D39-8E8E-D20F2B4C2E5C@cs.huji.ac.il>

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On Fri, May 1, 2020 at 3:54 AM Daniel Braniss <danny@cs.huji.ac.il> wrote:

>
>
> > On 1 May 2020, at 11:42, Trond Endrest=C3=B8l <trond.endrestol@ximalas.=
info>
> wrote:
> >
> > On Fri, 1 May 2020 11:16+0300, Daniel Braniss wrote:
> >
> >> hi,
> >> I have none efi boot that:
> >>      - the bios is set to do network boot/pxe
> >>      - if the dhcpd.conf is configured with filename set to pxeboot, i=
t
> loads as diskless,
> >>        or if set to =E2=80=9Cpmbr=E2=80=9D then goes and boots off the=
 hard disk.
> >>      (this is faster than changing the bios boot order)
> >>
> >>
> >> so now i'm experimenting with efi boot,
> >> the GPT is:
> >>
> >> =3D>         40      5857345456  mfid0  GPT  (2.7T)
> >>              40      409600                1  efi (200M)
> >>      409640     8388608               2  freebsd-ufs  ( 4.0G)
> >>    8798248   100663296             3  freebsd-swap  (48G)
> >> 109461544  5747883952            4  freebsd-zfs     (2.7T)
> >>
> >> but am at loss figuring out what boot file to download.
> >> any insight is appreciated,
> >
> > You can try this:
> >
> > gpart bootcode -p /boot/boot1.efifat -i 1 mfid0
> >
> > This will populate /dev/mdid0p1 with a FAT filesystem containing
> > /boot/boot1.efi, saved as efi/boot/BOOTx64.efi. You may later replace
> > the latter file with /boot/loader.efi. You will also find
> > efi/boot/startup.nsh which simple instructs the boot firmware to load
> > and run BOOTx64.efi.
> >
> > I haven't worked out how you can grow the small 800K FAT filesystem to
> > take advantage of your 200M partition. And indeed, we will need an ESP
> > of more than 800K in the near future.
> >
> > This fstab entry might be handy:
> >
> > # Device      Mountpoint      FStype  Options
>  Dump    Pass#
> > /dev/mfid0p1  /esp            msdosfs rw,-l,-m=3D664,-M=3D775,noauto   =
   0
>      0
> >
> > --
> > Trond.
>
>
> the fat partition is fine, has all that is needed, but
> I need the right bootblock instead of pmbr, and there are many  *efi* in
> /boot and I don=E2=80=99t
> know which one to use :-(
>

You don't need boot blocks in UEFI.

Create the FAT partition, use newfs_msdos to initialize it. mount it and
create a top-level directory named EFI.

There are several options from here:

(1) use the 'old style' of putting boot1.efi or loader.efi into
EFI/BOOT/BOOTX64.EFI. If you have a really simple setup, this is likely the
easiest. It usually works (though there are exceptions for some crazy
BIOSes). This works because the UEFI BIOS looks for removable devices with
a ESP that has /EFI/BOOT/BOOTxxx.EFI (where xxx varies on architecture, for
AMD64 its X64). It loads this. Both boot1.efi and loader.efi know what to
do from here if your root filesystem is on the same disk as the ESP.
boot1.efi searches a little harder for things, while loader.efi is more
disciplined in what it searches for to allow for predictable behavior. This
option works great for a FreeBSD only machine.

(2) Use the new style. mount the esp somewhere, say /boot/efi. Put
loader.efi into /boot/efi/EFI/FreeBSD and use the following command:
efibootmgr --create --loader /boot/efi/efi/freebsd/loader.efi --kernel
/boot/kernel/kernel --label "FreeBSD Rocks" --activate --verbose

which creates and activates a UEFI boot variable, that tells it to load
loader.efi first and have it load the default kernel and to label it
"FreeBSD Rocks".

This also works well for FreeBSD only machines and gives you more control
if you are doing things like having redundant partitions and you want to
nail down exactly the right one. This also works for people that want to
have multiple versions of FreeBSD on the machine (though 11 and older works
less well than 12 and newer).

(3) There are a number of 3rd party chain loaders rEFInd is likely the most
popular. I don't use those, so I can't comment on them further. These work
well when you have multiple OSes that each have their own fussy notion of
the proper early boot setup.

Warner



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