Date: Mon, 1 Sep 2025 20:42:43 +0900 From: Tomoaki AOKI <junchoon@dec.sakura.ne.jp> To: Warner Losh <imp@bsdimp.com> Cc: Poul-Henning Kamp <phk@phk.freebsd.dk>, Graham Perrin <grahamperrin@gmail.com>, FreeBSD-CURRENT <freebsd-current@freebsd.org> Subject: Re: Using a recovery partition to repair a broken installation of FreeBSD Message-ID: <20250901204243.6548150b14d79d2eab04ad3d@dec.sakura.ne.jp> In-Reply-To: <CANCZdfrrybisM6gSvsqKHfT2yk6ACXH=g=0oae1iVGBAdwWZQg@mail.gmail.com> References: <7b384ac0-9b24-43a4-bf63-012d745155a7@gmail.com> <aKD970iOlzyQNi0d@amaryllis.le-fay.org> <18e1a7e9-07d8-43a2-96af-0acdab6c2920@gmail.com> <babf662e-cded-4a2c-b5e8-c5a7175739f2@gmail.com> <20250901175827.73ba0ea24812cebe2263811f@dec.sakura.ne.jp> <202509010904.58194iP2007318@critter.freebsd.dk> <CANCZdfrrybisM6gSvsqKHfT2yk6ACXH=g=0oae1iVGBAdwWZQg@mail.gmail.com>
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On Mon, 1 Sep 2025 03:15:50 -0600 Warner Losh <imp@bsdimp.com> wrote: > On Mon, Sep 1, 2025, 3:05 AM Poul-Henning Kamp <phk@phk.freebsd.dk> wrote: > > > -------- > > Tomoaki AOKI writes: > > > > > > > > > … it would be nice to have something like 'recovery partition', as > > > > some OSes have. or at least some tiny fail-safe feature. having remote > > > > machine in some distant datacenter, booting from a flashstick is > > always > > > > a problem. > > > > I thought that is what /rescue is for ? > > > > That only works if your boot loader can read it... I've thought for a > while now that maybe we should move that into a ram disk image that we fall > back to if the boot loader can't read anything else... > > Warner Exactly. If the loader (or bootcode to kick the loader in the partition/pool) can sanely read the partition/pool to boot from, I think /rescue is enough and no need for rescue "partition / pool". But once the partition / pool to boot is broken (including lost decryption key for encrypted partitions/drives from regular place), something others are needed. And what can be chosen to boot from BIOS/UEFI firmware depends on the implementation (some could restrict per-drive only, instead of every entry in EFI boot manager table). If BIOS/firmware allow to choose "drive" to boot, rescue "drive" is useful, if multiple physical drives are available. Yes, rescue mfsroot embedded into loader.efi would be a candidate, too, if the size of ESP allows. > > -- > > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > phk@FreeBSD.ORG | TCP/IP since RFC 956 > > FreeBSD committer | BSD since 4.3-tahoe > > Never attribute to malice what can adequately be explained by incompetence. -- Tomoaki AOKI <junchoon@dec.sakura.ne.jp>help
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