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Date:      Fri, 18 Jan 2019 22:44:28 +0300
From:      Lev Serebryakov <lev@FreeBSD.org>
To:        Warner Losh <imp@bsdimp.com>
Cc:        FreeBSD Current <freebsd-current@freebsd.org>
Subject:   Re: GPT boot has less features than legacy MBR-based one (Was: UEFI,  loader.efi and /boot.config)
Message-ID:  <1f45099e-6a37-3edb-6bd4-f92eb2c4fde8@FreeBSD.org>
In-Reply-To: <CANCZdfon0uV1t=dLE2gcnLRW9DGFmiPgQjtv0zgFE-a3nD2ZRA@mail.gmail.com>
References:  <etPan.5c413a8a.7a8e2073.13b3@freebsd.org> <eb14f962-1c13-cc77-0e8c-575028f7c5d7@FreeBSD.org> <CA%2Bq%2BTcp2%2BsavH1g0q3b9YQ9SW76iXZ2PA6wvj2ok-cUOndZeWw@mail.gmail.com> <CACNAnaGm0AYmWO_T7yau1jYTxQE7i7LXceERDoHHBO1U%2BvTtSQ@mail.gmail.com> <b9223144-fd39-d84f-d310-d8d69f20561a@FreeBSD.org> <CANCZdfp_s1EhHGxd3BzviGV-s%2ByutCqF1csMJ56TZ1n6gtO1tA@mail.gmail.com> <d7829f9c-4526-144b-5eb6-93d2fe8b0376@FreeBSD.org> <8DDD8F7A-40CA-48BB-9F71-56733100AFE0@me.com> <1a19320b-2211-129c-b213-96601814e0d0@FreeBSD.org> <CANCZdfon0uV1t=dLE2gcnLRW9DGFmiPgQjtv0zgFE-a3nD2ZRA@mail.gmail.com>

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From: Lev Serebryakov <lev@FreeBSD.org>
Reply-To: lev@FreeBSD.org
To: Warner Losh <imp@bsdimp.com>
Cc: FreeBSD Current <freebsd-current@freebsd.org>
Message-ID: <1f45099e-6a37-3edb-6bd4-f92eb2c4fde8@FreeBSD.org>
Subject: Re: GPT boot has less features than legacy MBR-based one (Was: UEFI,
 loader.efi and /boot.config)
References: <etPan.5c413a8a.7a8e2073.13b3@freebsd.org>
 <eb14f962-1c13-cc77-0e8c-575028f7c5d7@FreeBSD.org>
 <CA+q+Tcp2+savH1g0q3b9YQ9SW76iXZ2PA6wvj2ok-cUOndZeWw@mail.gmail.com>
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 <b9223144-fd39-d84f-d310-d8d69f20561a@FreeBSD.org>
 <CANCZdfp_s1EhHGxd3BzviGV-s+yutCqF1csMJ56TZ1n6gtO1tA@mail.gmail.com>
 <d7829f9c-4526-144b-5eb6-93d2fe8b0376@FreeBSD.org>
 <8DDD8F7A-40CA-48BB-9F71-56733100AFE0@me.com>
 <1a19320b-2211-129c-b213-96601814e0d0@FreeBSD.org>
 <CANCZdfon0uV1t=dLE2gcnLRW9DGFmiPgQjtv0zgFE-a3nD2ZRA@mail.gmail.com>
In-Reply-To: <CANCZdfon0uV1t=dLE2gcnLRW9DGFmiPgQjtv0zgFE-a3nD2ZRA@mail.gmail.com>

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On 18.01.2019 22:27, Warner Losh wrote:

>     > errm.. you press a key and enter device and or loader path. if it=

>     is not working - the code is there to be fixed.
>     =C2=A0And loader looks to "bootme" attribute and try to boot from p=
artition
>     which has one, even if it is loaded from other partition itself.
> Correct.
 And system crashes, because "bootme" partition has broken installation.

 With MBR + boot0/boot0sio it is solved with one keypress.

>     > GPT does not have the concept of active partition.
>     =C2=A0It has "bootme" / "bootonce" attributes. And [zfs]gptboot doe=
sn't have
>     any tools to set these attributes, AFAIK. Same for UEFI boot code.
>=20
> gpart can set these.
 You need live, booted system (at least single-user) to use gpart.

> UEFI completely ignores them, though, because getting to that data is
> hard in the UEFI environment. But in UEFI, you're supposed to use
> BootXXXX and BootOrder/BootNext as managed by efibootmgr.
 Again, you need booted system to use efibootmgr.

  boot0/boot0sio works before system and could switch boot partition in
case of MBR. It is why I write, that GPT/Legacy and GPT/UEFI miss
important feature which is present for MBR boot for ages. Which is sad &
funny at same time, as GPT/UEFI has much more code than 512 bytes of boot=
0.

--=20
// Lev Serebryakov


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