From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=5.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,NICE_REPLY_A,RCVD_IN_DNSWL_NONE autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 23503 invoked from network); 23 Feb 2021 20:29:42 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 23 Feb 2021 20:29:42 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 1E2939C82C; Wed, 24 Feb 2021 06:29:39 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id AE4279C6D0; Wed, 24 Feb 2021 06:29:10 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=fail reason="signature verification failed" (1024-bit key; secure) header.d=tnetconsulting.net header.i=@tnetconsulting.net header.b="EtDlrVUI"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id 51B7D9C6D0; Wed, 24 Feb 2021 06:29:07 +1000 (AEST) Received: from tncsrv06.tnetconsulting.net (tncsrv06.tnetconsulting.net [45.33.28.24]) by minnie.tuhs.org (Postfix) with ESMTPS id 808C19C6CE for ; Wed, 24 Feb 2021 06:29:06 +1000 (AEST) Received: from Contact-TNet-Consulting-Abuse-for-assistance by tncsrv06.tnetconsulting.net (8.15.2/8.15.2/Debian-3) with ESMTPSA id 11NKT4qs030040 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NO) for ; Tue, 23 Feb 2021 14:29:05 -0600 DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=tnetconsulting.net; s=2019; t=1614112145; bh=7Ho9+3+V3HcZCc5BM7QqdUSDsqcHJhzb8MsH99EwADM=; h=Subject:To:References:From:Message-ID:Date:User-Agent: MIME-Version:In-Reply-To:Content-Type:Cc:Content-Disposition: Content-Language:Content-Transfer-Encoding:Content-Type:Date:From: In-Reply-To:Message-ID:MIME-Version:References:Reply-To: Resent-Date:Resent-From:Resent-To:Resent-Cc:Sender:Subject:To: User-Agent; b=EtDlrVUInWjSolMhXA/gGFszpuFfM19PVFiVHrc4n2g1YQsW7I1CdKASHheMJmSgq 1wchVcAS+4rLYqIUwk6F8KYrilwQwACio/N5leeiqD0sOEbcVrviqn/ml847qJZTTK iMblgWV/8utVpo6YrIp4IeqDFB9aUVQyayUOjQqA= To: tuhs@minnie.tuhs.org References: <78fede43-bf9b-5a56-5e59-e6ee5a0ee23d@spamtrap.tnetconsulting.net> Organization: TNet Consulting Message-ID: <3d2d7b46-41e8-92d7-3a7b-d0f3006bc761@spamtrap.tnetconsulting.net> Date: Tue, 23 Feb 2021 13:29:11 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="------------ms060109030501000900020501" Subject: Re: [TUHS] /usr separation X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Grant Taylor via TUHS Reply-To: Grant Taylor Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" This is a cryptographically signed message in MIME format. --------------ms060109030501000900020501 Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 2/23/21 11:57 AM, Theodore Ts'o wrote: > There are two reasons why you might want to have an initramfs. Rather than getting into a tit for tat debate, I'll agree that we have=20 both proposed reasons why you /might/ want to use an initramfs. The=20 operative words are "you" and "might". Each person probably wants=20 slightly different things. It's far from one size fits all. > The other reason is how you run fsck on the root file system. The same way that it's been done for years. Root is mounted read only=20 and you run fsck to repair damage. If it's severe damage, you will=20 likely need to boot off of something else. I've had both situations=20 happen multiple times. The quintessential max mount count / max days since last check have=20 happily been fixed while root was mounted read only. > That won't be needed if hardware is perfect, the kernel is=20 > bug-free(tm), and the root file system has journalling support,=20 > as all modern file systems tend to have. I wouldn't bet on that. I've had to run fsck on journalling file=20 systems at boot / mount time multiple times. > However, if it is needed, there are two ways to do this. One is the=20 > traditional way, which is to mount the root file system read/only,=20 > repair the file system, and if any changes were required to the root=20 > file system, force a reboot; otherwise, remount the root file system=20 > read-write, and proceed. This is what happened in /most/ of the cases that I've needed to=20 interact with fsck of a root file system. > The other way of doing this is to include the fsck program in the=20 > initrams, and run fsck on the root file system before it is mounted.=20 > Now you never have to worry about rebooting if any chances were made,=20 > since the root file system wasn't mounted and so there is no danger=20 > of invalid metadata being cached in memory. Oh ... I would definitely *NOT* say /never/. There are ways that a file = system can get corrupted that will cause fsck to stop and require manual = intervention. > That being said, it's certainly possible to skip using an initramfs;=20 > it's geenrally not required, and if you're building your own kernel,=20 > with the device drivers you need for your hardwaer compiled into=20 > the kernel, most distributions will support skipping the initramfs.=20 > (Debian certainly does, in any case.) And if you're building a minimal kernel, removing support for modules=20 and what's required for swing-root saves space. ;-) > /boot needs to exist due to limitations to the firmware and/or boot=20 > loader being used. Not necessarily. E.g. one single partition containing /boot and / (root)= =2E > If the boot loader is using the legacy PC Bios interfaces to read the=20 > kernel and initial ramdisk/file system, then those files need to be in = > a low-numbered LBA disk space, due to legacy BIOS/firmware limitations.= So make sure said /boot & / (root) partition stays within that=20 limitation. I don't recall exactly what that is. I think it's ~8 GB.=20 But it's definitely possible to have small installations in that space. > It could also be a concern if you are using some exotic file system=20 > (say, ZFS), and the bootloader doesn't support that file system due=20 > to copyright licensing incompatibilities, or the boot loader just not=20 > supporting that bleeding-edge file system. In that case, you might=20 > have to keep /boot as an ext4 file system. That scenario is definitely a possibility. Though such scenarios are=20 not a requirement and tend to be antithetical to minimal installations,=20 like the type that would be used in embedded devices and possibly copied = to ROM as indicated in a different post. > Other than that, there is no reason why /boot needs to be its own=20 > file system, except that most installers will create one just because=20 > it's simpler to use the same approach for all cases, even if it's=20 > not needed for a particular use case. As Steve Gibson is famous for saying; The tyranny of the default. > P.S. Oh, and if you are using UEFI, you might need to have yet=20 > another file system which is a Microsoft FAT file system, typically=20 > mounted as /boot/efi, to keep the UEFI firmware happy.... Yes, the file system needs to exist. But that's part of the firmware,=20 not the operating system. I also question if that FAT file system needs = to be mounted or not. -- I don't know how GRUB et al. deal with a=20 non-mounted UEFI file system. But even if it does need to be mounted, you can still get away with two=20 partitions; / (root) and /boot/efi. I suspect UEFI does away with the=20 LBA issue you mentioned. --=20 Grant. . . . unix || die --------------ms060109030501000900020501 Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Transfer-Encoding: base64 Content-Disposition: attachment; filename="smime.p7s" Content-Description: S/MIME Cryptographic Signature MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCC CzkwggUhMIIECaADAgECAhA/wgXwQl9mDHSg5enGHBeSMA0GCSqGSIb3DQEBCwUAMIGWMQsw CQYDVQQGEwJHQjEbMBkGA1UECBMSR3JlYXRlciBNYW5jaGVzdGVyMRAwDgYDVQQHEwdTYWxm b3JkMRgwFgYDVQQKEw9TZWN0aWdvIExpbWl0ZWQxPjA8BgNVBAMTNVNlY3RpZ28gUlNBIENs aWVudCBBdXRoZW50aWNhdGlvbiBhbmQgU2VjdXJlIEVtYWlsIENBMB4XDTIwMTExNjAwMDAw MFoXDTIxMTExNjIzNTk1OVowKzEpMCcGCSqGSIb3DQEJARYaZ3RheWxvckB0bmV0Y29uc3Vs dGluZy5uZXQwggEiMA0GCSqGSIb3DQEBAQUAA4IBDwAwggEKAoIBAQDM6cGNMlSUFPM3zVw+ VgSslz2QRtMj+FerQ0DpmgbhUzqm5hMRe0hMA2OBf41HDAeOV0RKcLx2+HozHlyQST2xagOX xiv91aEXezh8bEBfnOI564Ej/JfusomfoM7ByVXcLp3K3fOssHos6IXiAD6WT+jcRs7Cg+Gl 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