• [gentoo-dev] Last rites: sys-fs/eudev

    From Mike Gilbert@21:1/5 to All on Sat Nov 27 01:30:02 2021
    # eudev will be removed on 2022-01-01.
    # Please see the news item published on 2021-08-24 for more information. sys-fs/eudev

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  • From Jaco Kroon@21:1/5 to All on Tue Aug 30 12:00:01 2022
    Hi Mike, Sam

    This is the last I saw on the ML regarding eudev - has there been a
    change of strategy regarding eudev since?

    I note that the default provider for the virtual is systemd-utils[udev], followed by sys-fs/udev, sys-fs/eudev and finally sys-apps/systemd. 
    This contradicts the wiki page which states that sys-fs/udev is the
    default (https://wiki.gentoo.org/wiki/Udev).

    Is there more comprehensive documentation around about this, and which
    should be preferred when?

    The commit to un-last-rite this is the only information I can find, and
    I don't see major releases since.

    commit e170e1bb4c9ac1f63267298aa8eaab0d8f03c5e4
    Author: Sam James <sam@gentoo.org>
    Date:   Mon Dec 20 23:13:58 2021 +0000

        profiles: unmask/un-last-rite eudev
        
        It's now being maintained by a new upstream. I still recommend users     use sys-fs/udev as sys-fs/eudev has not been rebased on newer
        upstream (yet?) but this allows choice for people who feel
        strongly about this, I suppose.
        
        Boot-tested and e.g. udevadm seems to work correctly with new
        hwdb bits.
        
        Thanks-to: kurly
        Signed-off-by: Sam James <sam@gentoo.org>


    Kind Regards,
    Jaco

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  • From Arve Barsnes@21:1/5 to Jaco Kroon on Tue Aug 30 12:30:01 2022
    On Tue, 30 Aug 2022 at 11:52, Jaco Kroon <jaco@uls.co.za> wrote:
    I note that the default provider for the virtual is systemd-utils[udev], followed by sys-fs/udev, sys-fs/eudev and finally sys-apps/systemd.
    This contradicts the wiki page which states that sys-fs/udev is the
    default (https://wiki.gentoo.org/wiki/Udev).

    Is there more comprehensive documentation around about this, and which
    should be preferred when?

    sys-fs/udev is also just a virtual now, which pulls in
    systemd-utils[udev], so using either works exactly the same.

    Regards,
    Arve

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  • From Jaco Kroon@21:1/5 to Arve Barsnes on Tue Aug 30 14:30:01 2022
    Hi Arve,

    On 2022/08/30 12:27, Arve Barsnes wrote:

    On Tue, 30 Aug 2022 at 11:52, Jaco Kroon <jaco@uls.co.za> wrote:
    I note that the default provider for the virtual is systemd-utils[udev],
    followed by sys-fs/udev, sys-fs/eudev and finally sys-apps/systemd.
    This contradicts the wiki page which states that sys-fs/udev is the
    default (https://wiki.gentoo.org/wiki/Udev).

    Is there more comprehensive documentation around about this, and which
    should be preferred when?
    sys-fs/udev is also just a virtual now, which pulls in
    systemd-utils[udev], so using either works exactly the same.

    Thanks, I missed that.  That does help to clear things up.

    This leaves three implementations, systemd-utils[udev], eudev and systemd.

    We don't use systemd so that eliminates that, can I safely assume that systemd-utils[udev] is "extracted" from systemd and really the same
    thing?  Ie, it's the udevd without the associated systemd environment? 
    So really only two implementations.

    eudev then is the wild horse in that it was forked from the days when sys-fs/udev got incorporated into systemd, and have been following a
    parallel but somewhat independent path?  It doesn't contain many of the
    newer systemd-udev "features" and "lags behind"?

    Which, assuming then my understanding is now improved (which I believe
    it is), then the selection should be based as follows:

    1.  If you're using systemd, use the embedded udevd.
    2.  If you're using openrc, you should prefer sys-fs/udev aka systemd-utils[udev] unless you have a specific reason to rather use eudev?

    eudev has served me very well for very long, and avoided a fair number
    of LVM related deadlock issues we experienced with sys-fs/udev at the
    time.  We've been moving back, and I'm not convinced those have been eliminated, but I could not yet prove any of the recent system deadlocks
    we've seen relates to systemd-udev.

    (The one deadlock we did manage to trap was without a doubt something
    with the linux kernel IO scheduler, possibly related to raid6, however,
    lvm is also involved in that path, which does involve udev.  Also the
    system that most frequently runs into problems - only one with software
    raid6, but it also by far makes the most aggressive use of lvm
    snapshots.  Thus no definitive patterns.)

    Being a creature of habit based on experience I am sceptical.  I am contemplating throwing that one host back to eudev and seeing if that
    "solves" the problem ... but how long is a piece of string.

    Thanks for the information, I'll let the above simmer a good long while.

    Kind Regards,
    Jaco

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