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Date:      Fri, 27 Jan 2017 19:39:16 +0200
From:      Toomas Soome <tsoome@me.com>
To:        Allan Jude <allanjude@freebsd.org>
Cc:        Warner Losh <imp@bsdimp.com>, "Ngie Cooper (yaneurabeya)" <yaneurabeya@gmail.com>, FreeBSD Current <current@freebsd.org>
Subject:   Re: gptzfsboot grew a lot after skein support was added; need knob to control bloat
Message-ID:  <A8AEB974-4221-4471-8E69-81C83B92CFE9@me.com>
In-Reply-To: <444df1a4-1f27-49a8-6fa6-81f5853e6d80@freebsd.org>
References:  <A33154F2-70E1-4047-8496-7D4D85CFF292@gmail.com> <EF719374-BF9D-44EF-9F45-53B2B506047C@me.com> <CANCZdfrzOr3YdbAKRrwUXsFDhdQ3hErf1vbYSG7MdpV_m%2B=YRQ@mail.gmail.com> <444df1a4-1f27-49a8-6fa6-81f5853e6d80@freebsd.org>

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> On 27. jaan 2017, at 19:30, Allan Jude <allanjude@freebsd.org> wrote:
>=20
> On 2017-01-27 12:05, Warner Losh wrote:
>> On Fri, Jan 27, 2017 at 12:34 AM, Toomas Soome <tsoome@me.com =
<mailto:tsoome@me.com>> wrote:
>>>=20
>>>> On 27. jaan 2017, at 1:40, Ngie Cooper (yaneurabeya) =
<yaneurabeya@gmail.com> wrote:
>>>>=20
>>>> Hi,
>>>>      I tried upgrading one of my workstations and unfortunately the =
freebsd-boot partition is too small (I follow manpage directions, =
exactly, and those seem to be too small as of 10.3-RELEASE timeframe), =
and I don=E2=80=99t have enough space or ability to resize the partition =
and make it bigger. So, I=E2=80=99m in need of a build knob to control =
the bloat, and/or having an alternative boot loader without =
geli/skein/crypto support compiled in. Would you be opposed to the work?
>>>> Thanks,
>>>> -Ngie
>>>=20
>>>=20
>>> I do agree that since the geli knob is already there, it may do. Of =
course we also can think of additional knobs, but there is an issue - it =
wont help just to exclude some files, the additional features also do =
sit in the code, so the replacement stubs will be needed, also testing =
them all over will take some time. And the preprocessor spaghetti really =
is nasty thing to deal with;)
>>>=20
>>> And then there is another issue (partly why I did the feature =
support in first place) - as the kernel does not block user from =
enabling the features, the user can end up facing non-bootable setup =
which is also not good, as user is using perfectly legal options, and =
still the whole thing is just rendered unusable=E2=80=A6
>>=20
>> I'm curious why you can't find the space for a bigger partition?
>> Almost all drives these days are partitioned with a little wasted
>> space, and that wasted space should be more than enough to cover us
>> here. Also, most drives have a swap partition that can be shrunk a
>> trivial amount to get space for this...
>>=20
>> Warner
>>=20
>=20
> I need to do some testing to make a recipe that works for it, but the
> other option is to use the ZFS bootcode area.
>=20
> ZFS it self, reserves something like 3.5 mb of space in the ZFS
> partition, for boot code. This is how we boot ZFS on MBR.
>=20
> It should be possible to use this on GPT as well, we just don't.
>=20
>=20

Indeed it is. this is how the illumos is doing, except that what in =
illumos, we use also a bit different boot method - instead of browsing =
the partition table, we record the boot2 start and size in pmbr, and the =
partition start in gptzfsboot, and we always boot based on recorded =
location - that does simplify the boot code in pmbr, but needs install =
tool, to detect and record the LBA.

And for fbsd case, the bootblock install must be able to distinguish =
geli/non-geli setups, and .. well, there are some complications:)

rgds,
toomas





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