Re: [systemd-devel] Impact when not loading ipv6 and autofs kernel module ...

2013-09-11 Thread Lennart Poettering
On Wed, 14.08.13 16:43, Hoyer, Marko (ADITG/SW2) (mho...@de.adit-jv.com) wrote:

 For what is systemd using the loopback so that it has to set it up so
 early? Is there any impact when I'm setting up the loopback later. We
 are probably in a situation where we need ipv4 for general purposes
 and ipv6 for only special ones. So we'd like to set up ipv6 later for
 performance reasons, which concerns especially the module loading.

Humm, I doubt that initializing IPv6 early will really slow things down
for you.

The reason we initialize the loopback device this early is simply that
most userspace code simply expects it to be there, and working, and it's
absolutely trivial and fast to do, so we just do it by default, so that
it just works and is nothing the user can manually configure and where
we then have to parse configuraiton files and have another distinct
component running late in boot dealing with this and so on...

It's really something we want to be quick, and always done and
non-configurable and since its a triviality to do we just do it in PID 1...

Lennart

-- 
Lennart Poettering - Red Hat, Inc.
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Re: [systemd-devel] Impact when not loading ipv6 and autofs kernel module ...

2013-08-14 Thread Hoyer, Marko (ADITG/SW2)
 -Original Message-
 From: Lennart Poettering [mailto:lenn...@poettering.net]
 Sent: Friday, August 09, 2013 5:49 PM
 To: Hoyer, Marko (ADITG/SW2)
 Cc: systemd-devel@lists.freedesktop.org
 Subject: Re: [systemd-devel] Impact when not loading ipv6 and autofs kernel
 module ...
 
 On Wed, 07.08.13 11:24, Hoyer, Marko (ADITG/SW2) (mho...@de.adit-jv.com)
 wrote:
 
  Hello systemd developers,
 
  I found that systemd automatically tries to load ipv6 and autofs kernel
 modules, when they are not compiled in.
  Could you give me a hint what is not working, when they are neither provided
 as kernel modules nor compiled in?
 
  In case of autofs I found that automount units are not working any more (I
 would have expected this). Without ipv6 I can't find any problems by now.
 
  So:
 
 
  1.   Is there any other impact but the described one when the
  autofs kernel feature is missing?
 
 No. .automount units become unavailable, but that's all.
 
  2.   What impact do I have to expect in case the kernel does not provide
 ipv6 functionality?
 
 Well, support for IPv6 goes away, of course. The reason we explicitly load the
 module at early boot is that we try to configure the loopback device to ::1,
 but that can only work if IPv6 is available in the kernel. Doing this kind of
 loopback configuration of IPv6 however is not hooked up to the kernel-side
 auto-loading of ipv6.ko hence we load it explicitly from usersapce.
 
 Lennart

Thx for the input.

For what is systemd using the loopback so that it has to set it up so early? Is 
there any impact when I'm setting up the loopback later. We are probably in a 
situation where we need ipv4 for general purposes and ipv6 for only special 
ones. So we'd like to set up ipv6 later for performance reasons, which concerns 
especially the module loading.

 
 --
 Lennart Poettering - Red Hat, Inc.


Best regards

Marko Hoyer
Software Group II (ADITG/SW2)

Tel. +49 5121 49 6948
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[systemd-devel] Impact when not loading ipv6 and autofs kernel module ...

2013-08-07 Thread Hoyer, Marko (ADITG/SW2)
Hello systemd developers,

I found that systemd automatically tries to load ipv6 and autofs kernel 
modules, when they are not compiled in.
Could you give me a hint what is not working, when they are neither provided as 
kernel modules nor compiled in?

In case of autofs I found that automount units are not working any more (I 
would have expected this). Without ipv6 I can't find any problems by now.

So:


1.   Is there any other impact but the described one when the autofs kernel 
feature is missing?

2.   What impact do I have to expect in case the kernel does not provide 
ipv6 functionality?


Thx for any input.

Best regards

Marko Hoyer
Advanced Driver Information Technology GmbH
Software Group II (ADITG/SW2)
Robert-Bosch-Str. 200
31139 Hildesheim
Germany
Tel. +49 5121 49 6948
Fax +49 5121 49 6999
mho...@de.adit-jv.com
ADIT is a joint venture company of Robert Bosch GmbH/Robert Bosch Car 
Multimedia GmbH and DENSO Corporation
Sitz: Hildesheim, Registergericht: Amtsgericht Hildesheim HRB 3438
Geschäftsführung: Wilhelm Grabow, Katsuyoshi Maeda
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Re: [systemd-devel] Impact when not loading ipv6 and autofs kernel module ...

2013-08-07 Thread Tom Gundersen
On Wed, Aug 7, 2013 at 1:24 PM, Hoyer, Marko (ADITG/SW2)
mho...@de.adit-jv.com wrote:
 2.   What impact do I have to expect in case the kernel does not provide
 ipv6 functionality?

I think the main problem is in case you were to somehow insmod the
ipv6 module after boot, in which case it probably won't be set up
correctly. Maybe someone else know of other problems?

Cheers,

Tom
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