Re: MM kernels - how to keep on the bleeding edge?

From: Michael Krufky
Date: Tue Jul 26 2005 - 19:41:53 EST

Andrew Morton wrote:

Michael Krufky <mkrufky@xxxxxxx> wrote:

[ tracking mm stuff ]

While we're on the topic of how -mm works, I have a question for you. How can I test a kernel source tree (during compilation) to determine whether it is a -mm tree or a -linus tree?

I will give you an example of what I am trying to do:

video4linux cvs is backwards compatible with older 2.6 kernels. We keep backwards compatibility so that users can install newer device drivers without having to compile an entire kernel. There are things like:


...all over the code that allows it to compile cleanly with many different versions. Our patching scripts eliminate these "compatibility tests" from the source when building patches, and only presents the code compatible with the correct kernel version, so this doesn't interfere with development or the patching process.

However, sometimes there are patches in -mm that are incompatable with -linus. An example of this is "Pavel's pm_message_t mangling" ... Testing for the numbered 2.6.x version isn't enough of a test in a case like this, but it would be nice to be able to develop against the most recent version of both the -mm tree and the -linus tree without having to revert patches. Of course, v4l has chosen to maintain compatibility with -mm, for the sake of patch generation, and I have a handy -linus-compat.patch on the side for now if I want to build cvs against -linus, until Pavel's patches get merged later on. But I'm sure things like this must happen all the time. How do others deal with issues like these automatically?

It doesn't matter which -mm version or which -linus version it is... I can already test for 2.6.x ... All that matters is if it is -mm or -linus. If there isn't already an answer to this question, maybe you can create a /linux/.mm file, or something like that. A Makefile can test for the presence of that file... or is there already a file present that is unique to the -mm tree?

Michael Krufky

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