On Mon, Jul 16, 2018 at 02:21:19PM +0200, Martijn Coenen wrote:
As of Linux 4.17, there are more than 30000 exported symbols in the kernel. There seems to be some consensus amongst kernel devs that the export surface is too large, and hard to reason about. Generally, these symbols fall in one of these categories: 1) Symbols actually meant for drivers 2) Symbols that are only exported because functionality is split over multiple modules, yet they really shouldn't be used by modules outside of their own subsystem 3) Symbols really only meant for in-tree use When module developers try to upstream their code, it regularly turns out that they are using exported symbols that they really shouldn't be using. This problem is even bigger for drivers that are currently out-of-tree, which may be using many symbols that they shouldn't be using, and that break when those symbols are removed or modified. This patch allows subsystem maintainers to partition their exported symbols into separate namespaces, and module authors to import such namespaces only when needed. This allows subsystem maintainers to more easily limit availability of these namespaced symbols to other parts of the kernel. It can also be used to partition the set of exported symbols for documentation purposes; for example, a set of symbols that is really only used for debugging could be in a "SUBSYSTEM_DEBUG" namespace.
To give people a bit more background here, this is something that both Andi Kleen and I talked about over a decade ago. Martijn based his work on Andi's original patches and made them all work well, something that I was unable to do :) His addition of using the build system to automatically generate a patch for a subsystem based on the symbol namespace changes is frickin amazing. Great work here, this is something that I have wanted for the kernel for a long time. greg k-h -- To unsubscribe from this list: send the line "unsubscribe linux-m68k" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
