[LEDE-DEV] Kernel version in next major release

[Mauro Mozzarelli]

I would go for option 1


There is little to gain from the new kernel and lots to risk in terms of 
time, compatibility, additional work.


On 07/10/17 12:43, Hauke Mehrtens wrote:
> We had some discussions in IRC about the kernel version which should be
> used in the next major release after 17.01.
>
> Probably we would target a release in January 2018, but you know our
> track record of hitting such plans. ;-)
>
> We came up with these options:
>
>
> 1. Release with kernel 4.9 only
>
> Most targets are already on kernel 4.9, so this will be the featest
> option. Kernel 4.9 will get support from Greg till Jan. 2019 and then
> probably Ben Hutchings will take over as this kernel version is used in
> Debian and he already maintains all the other kernel version used in Debian.
>
> Kernel 4.9 is already getting old, especially for targets where the main
> development happens in mainline, backporting this gets harder. (ARM64
> targets, some ARM targets, x86, ...)
>
>
> 2. Release with kernel 4.14 only
>
> This is about one year more recent and will get support from Greg for
> the next 6 years, so till end of 2023.
> The final kernel 4.14 will probably get released on 12. November 2017.
>
> Currently this is not supported by LEDE and the following task have to
> be done:
>   * Port the generic patches
>   * Make all the out of tree modules work with it
>   * Port all targets to this kernel version
>    * Some targets are not so well maintained any more and there an
> additional delay could be introduced.
>   * Find and fix all the new bugs
>    * This kernel is probably bigger again and we will have more size
> problems on devices with 4 MB flash
>
> This will probably add a delay of 3 months or more compared to using
> kernel 4.9.
>
>
> 3. Release with kernel 4.9 and 4.14
>
> Since now OpenWrt and LEDE always used one single kernel version in a
> release, but we could also release with two different versions. Then
> some targets can be upgraded to kernel 4.14 and some will stay at kernel
> 4.9.
>
> This will help with targets where most of the development happens in the
> upstream kernel as we do not have to backport so much. In the master
> branch we use different kernel versions anyway, so in general this is
> not a problem.
>
> To do this we have to do the following:
>   * Port the generic patches
>   * Make all the out of tree modules work with it
>   * Port some easy targets to this kernel version
>   * Find and fix all the new bugs
>
> This will result in some additional maintenance work, because we would
> have to maintain two kernel versions in parallel, but this is mostly
> only taking the most recent stable versions anyway.
>
> This will probably add a delay of 1 or 2 month compared to using kernel 4.9.
>
>
> Kernel 3.18 and 4.4 will not be included in the next major release after
> 17.01 and all targets which are still on these kernel versions when we
> branch of LEDE will not be included in the release.
>
>
> What is your opinion on this topic? Am I missing some arguments?
> Currently I would prefer solution 3 going with kernel 4.9 and 4.14.
>
>
> Hauke
>
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