[LITMUS^RT] LITMUS^RT on v4.9: call for testing

[Björn Brandenburg]

Dear LITMUS^RT community,

I’ve prepared an initial port of LITMUS^RT to Linux 4.9.13. It compiles and runs on my x86 box, and even survives light testing. Let’s make this the next release. Obviously, more testing and cleanup is required. Thus:

                 ******** Please help out with testing! ******** 

The port is in the wip-port branch on Github:

	https://github.com/LITMUS-RT/litmus-rt/commits/wip-port

Please give it a try.

Some details on what I’ve done:

First, I squashed the history of the current master branch, the result of which you can find in the sip-squashed branch:

	https://github.com/LITMUS-RT/litmus-rt/commits/wip-squashed

This branch is identical to the current master branch, modulo the simplified history.

Next, I’ve rebased wip-squashed on top of Linux 4.9.13. Some notes:

- the hrtimer API has changed; this required some adjustments.

- I’ve dropped the SRP ceiling blocking hook. This legacy implementation was no longer working right and causing too many problem. SRP support will have to be re-implemented (if anyone still cares).

- There were many merge conflicts due to regular kernel churn. Most of them I could resolve in ways that seem like they ought to work, but only heavy workloads will show if the kernel holds up. 

                 ******** What to do ******** 

- Download, compile, and run the version in the wip-port branch.

- Run on the machines that you usually use for your research and tests.

- Run with both debug and benchmarking configs.

- If you use non-x86 hardware, see if the kernel still compiles for your favorite platform.

- Run your usual benchmarks / workloads.

- Report any crashes / warnings / performance regressions / anything else surprising.

- Ideally, submit patches to fix both minor and major breakage. 

Note: you’ll need the latest liblitmus to work with this kernel.

I know testing is not the most fun activity on the planet, but if you want to have a stable base system for your next project, now is the time to chip in and help out the project. The plan is to make 4.9 the base version for at least the next two years, so any effort invested now is going to pay off for some time to come.

Thanks,
Björn