Re: [PATCH, v2] kbuild: Improve version string logic

David Rientjes
2009-10-14T00:00:24Z

On Tue, 13 Oct 2009, Linus Torvalds wrote:

> > IMHO yes. This change essentially creates a backwards incompatibility with
> > existing naming schemes. Requiring to patch the change out to preserve an
> > existing naming scheme just seems a tad unfriendly.
>
> Let's keep the old behavior by making the AUTO option an three-way choice
> ("none", "short", "auto"), and making sure that it actually takes work to
> choose "none" (and that "make oldconfig" doesn't choose it unless you
> explicitly made the choice before - so people who just re-use old .config
> files wouldn't get "none" by mistake).
>

I don't think you want to do that because it would require the .config to
be posted on bug reports, for example, to determine the setting of
CONFIG_LOCALVERSION_AUTO before you can interpret the kernel version. In
other words, you wouldn't know that "2.6.32-rc4" is actually 200 commits
beyond the actual release unless you also know that the .config has
CONFIG_LOCALVERSION_AUTO="none".

Instead, it's better to force something to be appended to the kernel
release when "git describe" shows a non-zero revision count as you
earlier suggested. When CONFIG_LOCALVERSION_AUTO is enabled, that would
be the output of scripts/setlocalversion; when it is disabled, it would be
a `+'. Only when scripts/setlocalversion returns nothing (we're at an
actual kernel release) will nothing be appended.

The following is on top of my "scripts: suppress setlocalversion output if
at tagged commit" patch from
http://marc.info/?l=linux-kernel&m=125542102631704

kbuild: improve version string logic

The LOCALVERSION= string passed to "make" will now always be appended to
the kernel version after CONFIG_LOCALVERSION, if it exists, regardless of
whether CONFIG_LOCALVERSION_AUTO is set or not. This allows users to
uniquely identify their kernel builds with a string.

scripts/setlocalversion will now always be called to determine whether
the repository is beyond a tagged (release) commit. With "scripts:
suppress setlocalversion output if at tagged commit", the output of this
script is empty when at a tagged commit.

If CONFIG_LOCALVERSION_AUTO is enabled, the unique SCM tag reported by
setlocalversion (or .scmversion) is appended to the kernel version, if it
exists. When CONFIG_LOCALVERSION_AUTO is not enabled, a `+' is appended
to the kernel version to represent that the kernel has been revised since
the last release.

The end result is this:

- when LOCALVERSION= is passed to "make", it is appended to the kernel
version,

- when CONFIG_LOCALVERSION_AUTO is enabled, a unique SCM identifier is
appended if the respository has been revised beyond a tagged commit,
and

- when CONFIG_LOCALVERSION_AUTO is disabled, a `+' is appended if the
repository has been revised beyond a tagged commit.

Also renames variables such as localver-auto and _localver-auto to more
accurately describe what they represent: localver-extra and
scm-identifier, respectively.

Signed-off-by: David Rientjes <rientjes@google.com>
---
Makefile | 32 ++++++++++++++++++++------------
1 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/Makefile b/Makefile
--- a/Makefile
+++ b/Makefile
@@ -898,9 +898,13 @@ $(vmlinux-dirs): prepare scripts
# $(localver)
# localversion* (files without backups, containing '~')
# $(CONFIG_LOCALVERSION) (from kernel config setting)
-# $(localver-auto) (only if CONFIG_LOCALVERSION_AUTO is set)
-# ./scripts/setlocalversion (SCM tag, if one exists)
-# $(LOCALVERSION) (from make command line if provided)
+# $(LOCALVERSION) (from make command line, if provided)
+# $(localver-extra)
+# $(scm-identifier) (unique SCM tag, if one exists)
+# ./scripts/setlocalversion (only with CONFIG_LOCALVERSION_AUTO)
+# .scmversion (only with CONFIG_LOCALVERSION_AUTO)
+# + (only without CONFIG_LOCALVERSION_AUTO
+# and repository is at non-tagged commit)
#
# Note how the final $(localver-auto) string is included *only* if the
# kernel config option CONFIG_LOCALVERSION_AUTO is selected. Also, at the
@@ -914,26 +918,30 @@ string = $(shell cat /dev/null \
localver = $(subst $(space),, $(string) \
$(patsubst "%",%,$(CONFIG_LOCALVERSION)))

-# If CONFIG_LOCALVERSION_AUTO is set scripts/setlocalversion is called
-# and if the SCM is know a tag from the SCM is appended.
-# The appended tag is determined by the SCM used.
+# scripts/setlocalversion is called to create a unique identifier if the source
+# is managed by a known SCM and the repository has been revised since the last
+# tagged (release) commit. The format of the identifier is determined by the
+# SCM's implementation.
#
# .scmversion is used when generating rpm packages so we do not loose
# the version information from the SCM when we do the build of the kernel
# from the copied source
-ifdef CONFIG_LOCALVERSION_AUTO
-
ifeq ($(wildcard .scmversion),)
- _localver-auto = $(shell $(CONFIG_SHELL) \
+ scm-identifier = $(shell $(CONFIG_SHELL) \
$(srctree)/scripts/setlocalversion $(srctree))
else
- _localver-auto = $(shell cat .scmversion 2> /dev/null)
+ scm-identifier = $(shell cat .scmversion 2> /dev/null)
endif

- localver-auto = $(LOCALVERSION)$(_localver-auto)
+ifdef CONFIG_LOCALVERSION_AUTO
+ localver-extra = $(scm-identifier)
+else
+ ifneq ($scm-identifier,)
+ localver-extra = +
+ endif
endif

-localver-full = $(localver)$(localver-auto)
+localver-full = $(localver)$(LOCALVERSION)$(localver-extra)

# Store (new) KERNELRELASE string in include/config/kernel.release
kernelrelease = $(KERNELVERSION)$(localver-full)