Date:   Wed, 15 Nov 2017 09:09:34 +0100
From:   Sebastian Gottschall <s.gottschall@...wrt.com>
To:     Willy Tarreau <w@....eu>
Cc:     Harsh Shandilya <msfjarvis@...il.com>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org
Subject: Re: Linux 3.10.108 (EOL)

Am 15.11.2017 um 05:32 schrieb Willy Tarreau:
> On Tue, Nov 14, 2017 at 11:40:31PM +0100, Sebastian Gottschall wrote:
>>> And anyway the end of life has been indicated on kernel.org for 18 months
>>> and in every announce in 2017, so it cannot be a surprize anymore :-) At
>>> least nobody seemed to complain for all this time!
>> itsn no surprise for sure, but that also means i have to stay on the old
>> kernel for these special devices and your argument about disable certain
>> parts which simply turned bigger over time is no option
>>
>> since it would remove features which existed before. its not that i enable
>> all features of the kernel. i use every kernel with the same options (some
>> are adjusted since they are renamed or moved)
> Then I have a few questions :
>    - how did you choose this kernel ? Or did you choose the hardware based
>      on the kernel size ?

i did not choose it. i port regular all kernels to the platforms i use 
including 4.4 and 4.9

but a few of these which are already ported to 4.4 and 4.9 will still 
run 3.10 for resource problems.

>    - what would have you done if 3.10 had not been LTS ?
using another LTS at that point :-)
>    - have you at least tried other kernels before claiming they are much
>      larger ? Following your principle, 3.2 should be smaller and 3.16 not
>      much larger. The former offers you about 6 extra months of maintenance,
>      the latter 3.5 years (https://www.kernel.org/category/releases.html).

i also used 3.2 before. sure

dont get me wrong i work with all kernels, also with latests. i do also 
not complain that 3.10 is now EOL

i just wanted to throw some stones on the bloated kernel problem which 
is increasing

>
>> but even then the kernel is turning into a ram and space eating monster if i
>> look on devices with 16 mb ram and 4 mb flash. this is mainly for
>> maintaining older hardware with latest updates.
> So why didn't you ask if it was possible to pursue the maintenance a bit a
> long time ago ? LTS maintenance is a collective effort and is done based on
> usage. If enough people have good reasons for going further it can be enough
> a justification to push the deadline. Now it's too late.

didnt know that. the LTS deadline was defined a long time ago. i follow 
up the mailing lists mainly for reviewing patches

and reporting feedback if required. if it see such a discussion i may 
get in touch with it too, but with hundrets of emails every days here 
its hard to follow anything

>> the more recent hardware is getting better here
>>
>> you dont seem to know how it is to work on wireless routers :-)
> Yes I do, I've been distributing a full blown load balancer distro on a
> 10 MB image (running on 3.10 as well). But I also know that sometimes
> you make some nice space savings on new kernels (xz/zstd compression,
> ability to remove certain useless stuff in these environments such as
> FS ACLs or mandatory locks, etc). Sure, upgrading to a new kernel on
> existing hardware is always a challenge. But it's also an interesting
> one.

i do use xz and i do use a modified squashfs which is even smaller than 
the xz one in the kernel

smallest router i run with linux has 8 mb ram and 2 mb flash. so i do 
know how to get all very small. 10 mb image is no issue for me. the 4 mb 
flashes devices are my problem.


>
> Also just to give you an idea, I've just compared the size of these
> kernels configured with "make allnoconfig" (and I verified that all
> of them were compressed using gzip) :
>
>    3.10.108 : 875 kB
>    4.4.97   : 522 kB
>    4.9.61   : 561 kB
>    4.14     : 566 kB

its a little bit unrealistic since you have to count in network 
subsystem, filesystem and drivers.

standard kernel with xz compression is about 800 - 900 kb for me in 3.10 
and 4.4 / 4.9 etc. is often more than 1 - 1.2 mb

sometimes just the 100 kb more count in and turn into a problem since i 
have to remove something from the image to get it fitting

if you are really interested i can give you a real comparisation using a 
comparable config on 3.10, 4.4 and 4.9 for a standard mips target

>
> So the argument that migrating away from 3.10 is hard due to the size
> doesn't stand much here :-)
its turning harder. i already ported 4.4 and 4.9 as i said. so i tried 
already if they are running or not. they do run, but they are bigger and 
do not fit for some targets
>
> Willy
>

-- 
Mit freundlichen Grüssen / Regards

Sebastian Gottschall / CTO

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