[needs-packaging] linux backports and related meta packages

[Anthony Wong]

There used to be linux-backports-modules packages in Ubuntu maintained by our kernel team before Quantal (the last release that have these packages is Precise). However these packages proved to be useful in our OEM projects, because we often need to support new devices and their support is not good enough in kernel, and so we need to use drivers from later kernels. As a result I would like to re-introduce them into Ubuntu. After talking to Leann she agrees to let us (the hardware enablement team) to take over the packages.

We have re-packaged the codes by using newer debian build tools and added a few more meta packages for more flexibility, and so package naming and versioning will be different from before. Besides, a new LP project [1] has been created for this effort.

Same as the previous incarnation of linux-backports-modules, these packages will need to be constantly updated (SRU) upon two cases:
  1. Kernel ABI bump: when kernel is updated, backports packages have to be rebuilt against the new kernel and uploaded.
  2. We need to add a new version of backports modules: since backports modules are derived from upstream kernel and upstream kernel is constantly evolving with bug fixes and support for new devices, at some point in time we will want new packages to be built for modules from new kernels. Example: current wifi backports package is called linux-backports-wifi-4.5-4.4.0-4, which consists of modules from linux kernel 4.5 and the package is built against Ubuntu kernel 4.4.0-4. In the future there might be a new package linux-backports-wifi-4.6-4.4.0-8, which uses modules from kernel 4.6 that built against Ubuntu kernel 4.4.0-8.

Source can be found in this PPA: https://launchpad.net/~linux-backports-team/+archive/ubuntu/staging/+packages

[1] https://launchpad.net/backports

[Anthony Wong (anthonywong)]

(subscribe ubuntu-release since we have passed feature freeze for 16.04 unfortunately)

[Timo Aaltonen (tjaalton)]

some comments:

- 'backports' is a generic name, so even though upstream uses that for the tarball I think the source package should be named 'linux-backports' (and the lp project too, maybe too late for that :)
- empty d/docs file
- can't build a source package by just bumping the abi.. claims I don't have the headers installed which I do

[Anthony Wong (anthonywong)]

@Phid, please fix according to Timo's comment asap.

[Anthony Wong (anthonywong)]

Could someone from release team comment on these new packages?

[Phidias (phidias-chiang)]

@Timo:
> 'backports' is a generic name

We want to hear opinions from release team as well, if release team think it's ok we tend not to change it at the last minute

> empty d/docs file

We have changelog.gz and copyright installed to /usr/share/doc, did you mean we need also fill d/docs file specifically?

> can't build a source package

If I understand correctly it's due to ABI bumping issue yesterday and you've sorted it out, is there still any issue when building package?

[Andy Whitcroft (apw)]

I would agree that backports is too generic. As your meta package is linux-backports-meta the logical name is linux-backports to match. Also as this package is locked to the specific version of the kernel against which it builds I would recommend you version the package in line with the kernel to which it matches. This is what we do with all the other version locked packages that the kernel-team maintains, see linux-signed as an example of how we handle versions there.

Also have you considered how this will work with LTSs and specifically with multiple lts backport kernels into the same release.

[Andy Whitcroft (apw)]

I note that the binary packages produced by the source backports are all linux-backports already so there is an inconsistancy here also suggesting the name be linux-backports. Also the binary packages are necessarily versioned so that more than one version can be installed. This brings them very much into the same shape as kernel packages, which adds to the argument that these should be versioned in sync with the kernels to which they apply.

[Phidias (phidias-chiang)]

@Andy:
Hi, we've made the change according to the suggestion. New ppa can be found here:
https://launchpad.net/~linux-backports-team/+archive/ubuntu/develope

It's still a temporary ppa, and if it meets the requirement we will put it to our staging ppa.

[Phidias (phidias-chiang)]

The link in #8 is now obsolete, please check https://launchpad.net/~linux-backports-team/+archive/ubuntu/devel/ now, thanks!

[Anthony Wong (anthonywong)]

On 24 March 2016 at 17:00, Andy Whitcroft <email address hidden> wrote:

>
> Also have you considered how this will work with LTSs and specifically
> with multiple lts backport kernels into the same release.

I think we have two options:

1. Do not provide linux-backports to LTS kernels; or
2. Introduce new packages by appending -lts-<series> to package name, such
as linux-backports-lts-<series> (source package name), which builds
packages using LTS kernel headers.

[Anthony Wong (anthonywong)]

Andy, Timo, et al, do you have any more comments on the packages? With the input from you, the packages have been updated and we think they are now in good shape.

[Timo Aaltonen (tjaalton)]

the clean target still expects to find matching kernel headers to be installed ('make clean mrproper'), that'd need to be fixed IMO

also the ABI number probably should be pulled from the version string instead of expecting a changelog entry of certain format.

[Martin Pitt (pitti)]

Unsubscribing sponsors, this still looks incomplete.

[Iain Lane (laney)]

Same for release - please update & re-subscribe if/when this is active again