kernel/git/stable/linux-stable.git/Documentation/kbuild, branch linux-5.5.y

modpost: move the namespace field in Module.symvers last

2020-03-25T07:27:05+00:00

commit 5190044c2965514a973184ca68ef5fad57a24670 upstream. In order to preserve backwards compatability with kmod tools, we have to move the namespace field in Module.symvers last, as the depmod -e -E option looks at the first three fields in Module.symvers to check symbol versions (and it's expected they stay in the original order of crc, symbol, module). In addition, update an ancient comment above read_dump() in modpost that suggested that the export type field in Module.symvers was optional. I suspect that there were historical reasons behind that comment that are no longer accurate. We have been unconditionally printing the export type since 2.6.18 (commit bd5cbcedf44), which is over a decade ago now. Fix up read_dump() to treat each field as non-optional. I suspect the original read_dump() code treated the export field as optional in order to support pre <= 2.6.18 Module.symvers (which did not have the export type field). Note that although symbol namespaces are optional, the field will not be omitted from Module.symvers if a symbol does not have a namespace. In this case, the field will simply be empty and the next delimiter or end of line will follow. Cc: stable@vger.kernel.org Fixes: cb9b55d21fe0 ("modpost: add support for symbol namespaces") Tested-by: Matthias Maennich Reviewed-by: Matthias Maennich Reviewed-by: Lucas De Marchi Signed-off-by: Jessica Yu Signed-off-by: Masahiro Yamada Signed-off-by: Greg Kroah-Hartman

kbuild: clarify the difference between obj-y and obj-m w.r.t. descending

2019-12-21T15:25:35+00:00

Kbuild descends into a directory by either 'y' or 'm', but there is an important difference. Kbuild combines the built-in objects into built-in.a in each directory. The built-in.a in the directory visited by obj-y is merged into the built-in.a in the parent directory. This merge happens recursively when Kbuild is ascending back towards the top directory, then built-in objects are linked into vmlinux eventually. This works properly only when the Makefile specifying obj-y is reachable by the chain of obj-y. On the other hand, Kbuild does not take built-in.a from the directory visited by obj-m. This it, all the objects in that directory are supposed to be modular. If Kbuild descends into a directory by obj-m, but the Makefile in the sub-directory specifies obj-y, those objects are just left orphan. The current statement "Kbuild only uses this information to decide that it needs to visit the directory" is misleading. Clarify the difference. Reported-by: Johan Hovold Signed-off-by: Masahiro Yamada Reviewed-by: Johan Hovold

kconfig: remove ---help--- from documentation

2019-12-18T14:17:29+00:00

Since commit 84af7a6194e4 ("checkpatch: kconfig: prefer 'help' over '---help---'"), scripts/checkpatch.pl warns the use of ---help---. Kconfig still supports ---help---, but new code should avoid using it. Let's stop advertising it in documentation. Signed-off-by: Masahiro Yamada

kbuild: remove header compile test

2019-11-14T15:22:35+00:00

There are both positive and negative options about this feature. At first, I thought it was a good idea, but actually Linus stated a negative opinion (https://lkml.org/lkml/2019/9/29/227). I admit it is ugly and annoying. The baseline I'd like to keep is the compile-test of uapi headers. (Otherwise, kernel developers have no way to ensure the correctness of the exported headers.) I will maintain a small build rule in usr/include/Makefile. Remove the other header test functionality. Signed-off-by: Masahiro Yamada

kbuild: do not read $(KBUILD_EXTMOD)/Module.symvers

2019-11-11T11:07:03+00:00

Since commit 040fcc819a2e ("kbuild: improved modversioning support for external modules"), the external module build reads Module.symvers in the directory of the module itself, then dumps symbols back into it. It accumulates stale symbols in the file when you build an external module incrementally. The idea behind it was, as the commit log explained, you can copy Modules.symvers from one module to another when you need to pass symbol information between two modules. However, the manual copy of the file sounds questionable to me, and containing stale symbols is a downside. Some time later, commit 0d96fb20b7ed ("kbuild: Add new Kbuild variable KBUILD_EXTRA_SYMBOLS") introduced a saner approach. So, this commit removes the former one. Going forward, the external module build dumps symbols into Module.symvers to be carried via KBUILD_EXTRA_SYMBOLS, but never reads it automatically. With the -I option removed, there is no one to set the external_module flag unless KBUILD_EXTRA_SYMBOLS is passed. Now the -i option does it instead. Signed-off-by: Masahiro Yamada

Merge tag 'modules-for-v5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux

2019-10-11T17:19:24+00:00

Pull module fixes from Jessica Yu: "Code cleanups and kbuild/namespace related fixups from Masahiro. Most importantly, it fixes a namespace-related modpost issue for external module builds - Fix broken external module builds due to a modpost bug in read_dump(), where the namespace was not being strdup'd and sym->namespace would be set to bogus data. - Various namespace-related kbuild fixes and cleanups thanks to Masahiro Yamada" * tag 'modules-for-v5.4-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jeyu/linux: doc: move namespaces.rst from kbuild/ to core-api/ nsdeps: make generated patches independent of locale nsdeps: fix hashbang of scripts/nsdeps kbuild: fix build error of 'make nsdeps' in clean tree module: rename __kstrtab_ns_* to __kstrtabns_* to avoid symbol conflict modpost: fix broken sym->namespace for external module builds module: swap the order of symbol.namespace scripts: add_namespace: Fix coccicheck failed

doc: move namespaces.rst from kbuild/ to core-api/

2019-10-08T15:40:01+00:00

We discussed a better location for this file, and agreed that core-api/ is a good fit. Rename it to symbol-namespaces.rst for disambiguation, and also add it to index.rst and MAINTAINERS. Signed-off-by: Masahiro Yamada Acked-by: Matthias Maennich Signed-off-by: Jessica Yu

kheaders: make headers archive reproducible

2019-10-05T06:29:49+00:00

In commit 43d8ce9d65a5 ("Provide in-kernel headers to make extending kernel easier") a new mechanism was introduced, for kernels >=5.2, which embeds the kernel headers in the kernel image or a module and exposes them in procfs for use by userland tools. The archive containing the header files has nondeterminism caused by header files metadata. This patch normalizes the metadata and utilizes KBUILD_BUILD_TIMESTAMP if provided and otherwise falls back to the default behaviour. In commit f7b101d33046 ("kheaders: Move from proc to sysfs") it was modified to use sysfs and the script for generation of the archive was renamed to what is being patched. Signed-off-by: Dmitry Goldin Reviewed-by: Greg Kroah-Hartman Reviewed-by: Joel Fernandes (Google) Signed-off-by: Masahiro Yamada

kbuild: two minor updates for Documentation/kbuild/modules.rst

2019-10-05T06:29:49+00:00

Capitalize the first word in the sentence. Use obj-m instead of obj-y. obj-y still works, but we have no built-in objects in external module builds. So, obj-m is better IMHO. Signed-off-by: Masahiro Yamada

kbuild: correct formatting of header in kbuild module docs

2019-10-01T00:21:21+00:00

Minor formatting fixup. Fixes: cd238effefa2 ("docs: kbuild: convert docs to ReST and rename to *.rst") Signed-off-by: Alex Gaynor Signed-off-by: Matthew Garrett Signed-off-by: Masahiro Yamada