From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from lists.gentoo.org (pigeon.gentoo.org [208.92.234.80]) by finch.gentoo.org (Postfix) with ESMTP id A00FA13873B for ; Sun, 2 Mar 2014 17:45:54 +0000 (UTC) Received: from pigeon.gentoo.org (localhost [127.0.0.1]) by pigeon.gentoo.org (Postfix) with SMTP id 90F0CE0AD8; Sun, 2 Mar 2014 17:45:52 +0000 (UTC) Received: from mail-la0-f53.google.com (mail-la0-f53.google.com [209.85.215.53]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by pigeon.gentoo.org (Postfix) with ESMTPS id 83F99E0AD5 for ; Sun, 2 Mar 2014 17:45:51 +0000 (UTC) Received: by mail-la0-f53.google.com with SMTP id b8so3960999lan.26 for ; Sun, 02 Mar 2014 09:45:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type:content-transfer-encoding; bh=97tyMb+mM8Y5uIJ7vFFVQVrUFQkOejEQRoVpVVRMm0c=; b=0IW/xn72BrbhvVDizNhZ/iC+PU/rCtcKe171awQ/kCqH6hD7wxSeZSPlb9MvLq7Tik y9zYiDl6lJZFah7HwPuvIOQMziwr6pOEgltx4P8wM65PScto4ggLcxYNVBML+gAIW06a pbb9IO3N/MFIHv0ZCcpeVjJbPA5MOGUwh3LuSCaIEMiEhbyiVEDxeJ9C7kUa7nx8fQMy qC98U5gbY3GX8zzSz92VsY6W57ARYls6Pw11TAjkx9aUzj7E7tnnKr++UH43SGmbUdMr Vp0DJK94ACYi0zD6+Z6sFbTH1Aj3NsdQsER1rNtbjnrJHnMmWncwyXlTSrDIX8BmPOJh wGjA== Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-Id: Gentoo Linux mail X-BeenThere: gentoo-amd64@lists.gentoo.org Reply-to: gentoo-amd64@lists.gentoo.org MIME-Version: 1.0 X-Received: by 10.112.175.43 with SMTP id bx11mr107859lbc.51.1393782350010; Sun, 02 Mar 2014 09:45:50 -0800 (PST) Received: by 10.114.176.36 with HTTP; Sun, 2 Mar 2014 09:45:49 -0800 (PST) In-Reply-To: References: Date: Sun, 2 Mar 2014 11:45:49 -0600 Message-ID: Subject: Re: [gentoo-amd64] Please get me straight about sysvinit vs. systemd, udev vs eudev vs mdev, virtuals and other things... From: =?UTF-8?B?Q2FuZWsgUGVsw6FleiBWYWxkw6lz?= To: gentoo-amd64@lists.gentoo.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Archives-Salt: 2b1198c5-fa9b-4cd3-b81f-c2d19c8f1752 X-Archives-Hash: b0e8ac3a183a736e0b0156be94517b61 On Sun, Mar 2, 2014 at 10:57 AM, Mark Knecht wrote: > Hi all, > I'd like to check in and get some education concerning future > configuration of my Gentoo machines. Thanks in advance. > > In the last few days there is a news announcement about needing to > change kernel my configuration to enable CONFIG_FHANDLE to support > udev-210. I'm currently at udev-208 and virtual/udev-208-r1 so no big > deal yet. However reading the news announcement it appears this has > more to do with systemd than anything else and I don't use systemd so > does/will this effect my machines? Yes, it will; udev (independently of systemd) is using FHANDLE to find the devices in the computer. udev is part of systemd, but it can be used separately. This is supported by upstream (i.e., systemd). The change in the kernel config is needed by udev. > NOTE: I have no problem I know about today enabling CONFIG_FHANDLE > if it's recommended. It is: udev will not work without it. Even more: eudev (when they catch up) will not work without it either, since eudev does no original work; they just exorcise systemd from udev. > That said there's an interesting (if it is to be believed) little > rant thread over the last couple of days on LKML about Debian > leadership forcing people into systemd. The Debian Technical Committee took the technical decision of using systemd as default init system. There is no "forcing" here; Debian is ruled by a Constitution, and they (very slowly) followed their rules and laws to reach that decision. > I think the Gentoo devs forked > udev to make either mdev or eudev but when it was announced it was too > new for me so I just let it go by. Gentoo, by default, uses udev without systemd. Again, this is supported by upstream (i.e., systemd), nothing special about it. *Some* Gentoo developers "forked" systemd into eudev, so you can have a "udev without systemd" (although, as stated above, upstream supports udev without systemd). I don't know the exact numbers, but it's my impression (by reading -dev and -user), that eudev is used in Gentoo (and only Gentoo) by a handful of people. The great majority is using sys-fs/udev, and I'm willing to bet that more people are using systemd directly than eudev. > Maybe now it's time for me to look > into making a change of some type? I see eudev in portage, but not > mdev. Using eudev will gain you nothing; the FHANDLE change will reach them eventually. If you use mdev, you will have a noticeable loss of functionality. I think even less people use mdev than eudev. > A (really, really, really) quick scan of the current install docs > makes me think sysvinit/OpenRC/udev is still the default for new > installs. Is this true? Yes, it's true, and no one will propose changing this, at least in the near future. And even if systemd becomes the standard Gentoo init system, OpenRC will be (almost surely) supported until the end of times. > If so why is this kernel change being > required? Because is new functionality provided by the kernel required by *udev*, not (necessarily) systemd. Happens all the time; new technology in the kernel is pretty useless if userspace doesn't start taking advantage of it. > Also, I seem to have virtual/udev installed which says it's about > enabling switching between udev & eudev. However there are no files > associated with virtual/udev. (equery files virtual/udev returns > nothing) That's why it's a virtual; a virtual pulls in different implementations of the (in theory) same functionality. > It appears I cannot install eudev without removing udev so > this seems a big step to take: [ snip] It is a big step to take, and it will gain you nothing: eventually, eudev *will* require FHANDLE, unless they diverge even more from upstream, a thing I believe they cannot afford to do. > At this point I'm not even sure what my other questions might be as > I'm just trying to get my head around what others are using these > days. Well, it's undeniable that systemd usage is on the raising everywhere, including Gentoo (specially since GNOME pulls it in). I myself use systemd, and could not be happier. However, OpenRC is (and will be for the foreseeable future) the default init system. > I do have a second Gentoo install on this system on an SSD so > (once updated) I could do a switch there as a test. My suggestion is for you to enable FHANDLE. From the kernel: """ config FHANDLE bool "open by fhandle syscalls" select EXPORTFS help If you say Y here, a user level program will be able to map file names to handle and then later use the handle for different file system operations. This is useful in implementing userspace file servers, which now track files using handles inste= ad of names. The handle would remain the same even if file names get renamed. Enables open_by_handle_at(2) and name_to_handle_at(2= ) syscalls. """ It enables a couple of syscalls, and I don't think it will increase much your kernel size. All systemd forks (including eudev) will need it at some point, since it makes things easier for the developers. You *could* use mdev instead of udev, but is **NOT** a drop in replacement: you *will* lose some (if not much) functionality. So just enable the thing and go on with your life. My 0.02 ${CURRENCY}. Regards. --=20 Canek Pel=C3=A1ez Vald=C3=A9s Posgrado en Ciencia e Ingenier=C3=ADa de la Computaci=C3=B3n Universidad Nacional Aut=C3=B3noma de M=C3=A9xico