[Buildroot] [Bug 6596] New: Slow bootup if mdev is chosen

[Buildroot] [Bug 6596] New: Slow bootup if mdev is chosen

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6596

           Summary: Slow bootup if mdev is chosen
           Product: buildroot
           Version: 2013.08
          Platform: Other
        OS/Version: Linux
            Status: NEW
          Severity: minor
          Priority: P5
         Component: Other
        AssignedTo: unassigned at buildroot.uclibc.org
        ReportedBy: andreas.koop at zf.com
                CC: buildroot at uclibc.org
   Estimated Hours: 0.0


Created attachment 5090
  --> https://bugs.busybox.net/attachment.cgi?id=5090
disable CONFIG_UEVENT_HELPER_PATH option

When I choose mdev my Nios II based board stalls for about two minutes during
boot up. Then it proceeds again and boots normally. I've tracked the issue
down. It's because buildroot sets CONFIG_UEVENT_HELPER_PATH to "/sbin/mdev"
during kernel configuration. When I set it to an empty string Linux (3.10.0)
boots up as usual again.
If you look at the kernel's own description of CONFIG_UEVENT_HELPER_PATH it
states it shouldn't be used today anymore since it creates a high system load
on bootup.
Mdev still works after it's startup script has been run. It writes "/sbin/mdev"
to /proc/sys/kernel/hotplug which causes the kernel to inform mdev about new
events.

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[Buildroot] [Bug 6596] Slow bootup if mdev is chosen

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6596

--- Comment #1 from Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> 2013-10-24 08:19:22 UTC ---
We have had a discussion about this topic in the past:
http://lists.busybox.net/pipermail/buildroot/2013-July/075148.html

I indeed have noticed the same slowdown, and our solution was the same (setting
the UEVENT_HELPER to empty).

Given that the mentioned thread changed S10mdev to set mdev as helper after
boot, I don't think we still need/want the in-kernel option.

Would you mind sending this change as a proper patch to the mailing list,
including description and Signed-off-by? This would provide you with the
necessary credit, and also facilitates discussion on the patch.

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[Buildroot] [Bug 6596] Slow bootup if mdev is chosen

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6596

--- Comment #2 from Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> 2014-02-07 08:43:41 UTC ---
Patch sent to the mailing list, awaiting integration, after which this bug can
be closed...

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[Buildroot] [Bug 6596] Slow bootup if mdev is chosen

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6596

Thomas De Schampheleire <patrickdepinguin+buildroot@gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED

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[Buildroot] [Bug 6596] Slow bootup if mdev is chosen

[bugzilla at busybox.net]

https://bugs.busybox.net/show_bug.cgi?id=6596

Peter Korsgaard <jacmet@uclibc.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |FIXED

--- Comment #3 from Peter Korsgaard <jacmet@uclibc.org> 2014-02-09 22:17:00 UTC ---
Committed in git (05e2e35715d104e9dd67b4013d9b16a47b8eb3c0), thanks

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