Re: gptzfsboot grew a lot after skein support was added; need knob to control bloat

On Sat, Jan 28, 2017 at 12:04 PM, Ngie Cooper <yaneurabeya_at_gmail.com> wrote:
> On Sat, Jan 28, 2017 at 10:57 AM, Allan Jude <allanjude_at_freebsd.org> wrote:
>> On 2017-01-28 13:56, Ngie Cooper wrote:
>>> On Sat, Jan 28, 2017 at 8:56 AM, Warner Losh <imp_at_bsdimp.com> wrote:
>>>
>>> ...
>>>
>>>> So? It literally doesn't matter where the freebsd-boot partition
>>>> lives, or what it's number is. You can put it at the start or end of
>>>> the swap partition after adjusting its size. I've done this on several
>>>> systems...  NanoBSD plays games with this stuff as well to be bootable
>>>> on old / new systems.
>>>
>>> True. Hopefully my BIOS/disk controller isn't dumb enough to not
>>> support large disks properly.
>>>
>>> *sigh* Unfortunately, in my infinity cleverness I only put 2
>>> partitions on the drive -- freebsd-boot and freebsd-zfs. I guess I'll
>>> need to make backups of my workstation so I don't lose anything
>>> critical.
>>
>> Did gptzfsboot not fall below 64kb when you used the
>> LOADER_NO_GELI_SUPPORT knob?
>
> It did, but unfortunately that's still way too small for my
> freebsd-boot partition (which apparently is only 44kB large :/..):
>
> Before:
>
> $ ls -l `make -V.OBJDIR`/gptzfsboot
> -rw-r--r--  1 ngie  wheel  111662 Jan 28 11:00
> /usr/obj/usr/src/sys/boot/i386/gptzfsboot/gptzfsboot
>
> After:
>
> $ ls -l `make -V.OBJDIR`/gptzfsboot
> -rw-r--r--  1 ngie  wheel  65371 Jan 28 11:05
> /usr/obj/usr/src/sys/boot/i386/gptzfsboot/gptzfsboot
>
> Time to do some more tricks to pare down the bootloader size.

You can tweak the start of your boot loader partition to start at 2,
which would give you 63.5k of space, which is 65024 bytes. Sadly, this
is 300 bytes less space than you have.

The end of the disk usually is a good place to look for space, but it
looks like there's at most 17k there.

> Sidenote to the folks who drive the release notes and upgrade
> instructions for FreeBSD 12.x -- it needs to be clearly explained that
> gptzfsboot has grown considerably in size and mitigation instructions
> should be provided for updating gptzfsboot -- in particular with folks
> who might be using freebsd-update, so don't have the luxury of the
> choice of bootloader build options when upgrading.

Upgrade scripts (including installworld) don't update the bootblocks
ever. Just the files in /boot.

Warner

> Thanks,
> -Ngie
>
> $ gpart list da0
> Geom name: da0
> modified: false
> state: OK
> fwheads: 255
> fwsectors: 63
> last: 250069646
> first: 34
> entries: 128
> scheme: GPT
> Providers:
> 1. Name: da0p1
>    Mediasize: 45056 (44K)
>    Sectorsize: 512
>    Stripesize: 0
>    Stripeoffset: 20480
>    Mode: r0w0e0
>    rawuuid: 29a79300-48b1-11e4-97ff-fc4dd43f2de9
>    rawtype: 83bd6b9d-7f41-11dc-be0b-001560b84f0f
>    label: (null)
>    length: 45056
>    offset: 20480
>    type: freebsd-boot
>    index: 1
>    end: 127
>    start: 40
> 2. Name: da0p2
>    Mediasize: 128035593728 (119G)
>    Sectorsize: 512
>    Stripesize: 0
>    Stripeoffset: 65536
>    Mode: r1w1e1
>    rawuuid: 4416180d-48b1-11e4-97ff-fc4dd43f2de9
>    rawtype: 516e7cba-6ecf-11d6-8ff8-00022d09712b
>    label: (null)
>    length: 128035593728
>    offset: 65536
>    type: freebsd-zfs
>    index: 2
>    end: 250069646
>    start: 128
> Consumers:
> 1. Name: da0
>    Mediasize: 128035676160 (119G)
>    Sectorsize: 512
>    Mode: r1w1e2