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1 Problem finding

Compile the main line kernel Version found , After successfully compiling the kernel version of, the generated version number becomes "x.y.z+", Why is there a plus sign after it ?

At the beginning, I was wondering if CONFIG_LOCALVERSION The problem of , Configured with CONFIG_LOCALVERSION, It's still going to be added at the end of the kernel version "+" after , After installation , Every time uname -a Will appear + I really feel depressed after , Obsessive compulsive disorder I really can't stand .

2 Cause analysis

There must be problems linux Version control in the construction process , Since it was added during the build process , Then we can start from Makefile Some clues have been found in .

2.1 `Makefile` in `LOCALVERSION` Information

VERSION = 2
PATCHLEVEL = 6
SUBLEVEL = 35
EXTRAVERSION = .7
NAME = Yokohama

These are the version numbers of our kernel version , In theory, the generated version number should not carry + Number , But why + No.? .

There are two configuration macros in the kernel CONFIG_LOCALVERSION and CONFIG_LOCALVERSION_AUTO Configuration of the system kernel version number and suffix information .

2.2 `Makefile` Read and set the version number in the

We retrieve information about these two macros , Check LOCALVERSION Macro excludes arch/*/configs and Documentation Such as catalog .

scripts/setlocalversion:# CONFIG_LOCALVERSION and LOCALVERSION (if set)
scripts/setlocalversion:res="${res}${CONFIG_LOCALVERSION}${LOCALVERSION}"
scripts/setlocalversion:if test "$CONFIG_LOCALVERSION_AUTO" = "y"; then
scripts/setlocalversion: # LOCALVERSION= is not specified
scripts/setlocalversion: if test "${LOCALVERSION+set}" != "set"; then

You can see scripts/setlocalversion The script reads the relevant information .

take it easy , Let's slowly analyze , have a look Makefile How to read and set this information . Continue from Makefile Middle analysis LOVALVERSION Information about .

define filechk_kernel.release
echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"
endef
# Store (new) KERNELRELEASE string in include/config/kernel.release
include/config/kernel.release: include/config/auto.conf FORCE
$(call filechk,kernel.release)

Makefile Use scripts/setlocalversion Tools to generate include/config/kernel.release. “+” The sign is added when the script is called .

Then you can generate the version file by executing the following command

make include/config/kernel.release
OR
make include/generated/utsrelease.h

Look at the information of these two files to see the version number information

in addition Makefile There are also the following definitions :

kernelrelease:
@echo "$(KERNELVERSION)$$($(CONFIG_SHELL) $(srctree)/scripts/setlocalversion $(srctree))"

You can also directly use the following command to display the version number information

make kernelrelease

2.3 `setlocalversion` Function to set version number information

read scripts/setlocalversion file , And look up information , Take the following notes :

# If the current kernel uses SVN trusteeship , Only from .scmversion Read version number information in 
if $scm_only; then
if test ! -e .scmversion; then
res=$(scm_version)
echo "$res" >.scmversion
fi
exit
fi
# confirm auto.conf Does the file exist 
if test -e include/config/auto.conf; then
. include/config/auto.conf
else
echo "Error: kernelrelease not valid - run 'make prepare' to update it" >&2
exit 1
fi
# call localversion From the source root directory localversion The information is read from the file 
# localversion* files in the build and source directory
res="$(collect_files localversion*)"
if test ! "$srctree" -ef .; then
res="$res$(collect_files "$srctree"/localversion*)"
fi
# Set up LOCALVERSION Information 
# CONFIG_LOCALVERSION and LOCALVERSION (if set)
res="${res}${CONFIG_LOCALVERSION}${LOCALVERSION}"
# call scm_version Function to read suffix information 
# scm version string if not at a tagged commit
if test "$CONFIG_LOCALVERSION_AUTO" = "y"; then
# full scm version string
res="$res$(scm_version)"
else
# append a plus sign if the repository is not in a clean
# annotated or signed tagged state (as git describe only
# looks at signed or annotated tags - git tag -a/-s) and
# LOCALVERSION= is not specified
if test "${LOCALVERSION+set}" != "set"; then
scm=$(scm_version --short)
res="$res${scm:++}"
fi
fi

2.3.1 LOCALVERSION Set up

stay scripts/setlocalversion There's also a paragraph in it :

# CONFIG_LOCALVERSION and LOCALVERSION (if set)
res="${res}${CONFIG_LOCALVERSION}${LOCALVERSION}"

You can see that if you configure CONFIG_LOCALVERSION and LOCALVERSION This suffix will be added after the version number .

and res It is the local version number information obtained , such as 4.14-rc8

2.3.2 SCM_VERSION The addition of suffix information

Finally, it depends on whether it is configured CONFIG_LOCALVERSION_AUTO and CONFIG_LOCALVERSION macro , Add version suffix information

If you define

CONFIG_LOCALVERSION_AUTO=y

At this point the execution will be executed

res="$res$(scm_version)"

among res It's our version number information , and scm_version Function gets the version number suffix .

Otherwise, if it is not set CONFIG_LOCALVERSION_AUTO, Then execute the following fragment .

# call scm_version Function to read suffix information 
# scm version string if not at a tagged commit
if test "$CONFIG_LOCALVERSION_AUTO" = "y"; then
# full scm version string
res="$res$(scm_version)"
else
# append a plus sign if the repository is not in a clean
# annotated or signed tagged state (as git describe only
# looks at signed or annotated tags - git tag -a/-s) and
# LOCALVERSION= is not specified
if test "${LOCALVERSION+set}" != "set"; then
scm=$(scm_version --short)
res="$res${scm:++}"
fi
fi

about setlocalversion To explain the grammar of :

So the one above shell sentence

If CONFIG_LOCALVERSION_AUTO = y This program will go through scm_version function ( Without parameters ) Configure local version number .
If CONFIG_LOCALVERSION_AUTO Not set , and LOVALVERSION It's empty , be "${LOCALVERSION+set}" != "set", So called scm_version --short Will add a... At the end + Number .

So that's it , This is how the plus sign is added . How to add the plus sign , then , scm_version What kind of work has been done , How do these configuration macros affect the version number and suffix information , It's just research scm_version Function .

2.3.3 Version suffix information acquisition

scm_version()
{
local short
short=false
cd "$srctree"
# If there is .scmversion The file directly obtains the suffix information of the file 
if test -e .scmversion; then
cat .scmversion
return
fi
# --short Parameter settings 
if test "$1" = "--short"; then
short=true
fi
# Check for git and a git repo.
# Read git Version information of the warehouse 
# If --short Set to print directly + Number 
# otherwise git Read version number information ,
# If git tag Sign exists git describe | awk -F- '{printf("-%05d-%s", $(NF-1),$(NF))}'
# Otherwise print directly commit Number information 
if test -z "$(git rev-parse --show-cdup 2>/dev/null)" &&
head=`git rev-parse --verify --short HEAD 2>/dev/null`; then
# If we are at a tagged commit (like "v2.6.30-rc6"), we ignore
# it, because this version is defined in the top level Makefile.
if [ -z "`git describe --exact-match 2>/dev/null`" ]; then
# If only the short version is requested, don't bother
# running further git commands
if $short; then
echo "+"
return
fi
# If we are past a tagged commit (like
# "v2.6.30-rc5-302-g72357d5"), we pretty print it.
if atag="`git describe 2>/dev/null`"; then
echo "$atag" | awk -F- '{printf("-%05d-%s", $(NF-1),$(NF))}'
# If we don't have a tag at all we print -g{commitish}.
else
printf '%s%s' -g $head
fi
fi
# Is this git on svn?
if git config --get svn-remote.svn.url >/dev/null; then
printf -- '-svn%s' "`git svn find-rev $head`"
fi
# Check for uncommitted changes
# If there are uncommitted documents, add -dirty suffix 
if git diff-index --name-only HEAD | grep -qv "^scripts/package"; then
printf '%s' -dirty
fi
# All done with git
return
fi
# Check for mercurial and a mercurial repo.
if test -d .hg && hgid=`hg id 2>/dev/null`; then
# Do we have an tagged version? If so, latesttagdistance == 1
if [ "`hg log -r . --template '{latesttagdistance}'`" == "1" ]; then
id=`hg log -r . --template '{latesttag}'`
printf '%s%s' -hg "$id"
else
tag=`printf '%s' "$hgid" | cut -d' ' -f2`
if [ -z "$tag" -o "$tag" = tip ]; then
id=`printf '%s' "$hgid" | sed 's/[+ ].*//'`
printf '%s%s' -hg "$id"
fi
fi
# Are there uncommitted changes?
# These are represented by + after the changeset id.
case "$hgid" in
*+|*+\ *) printf '%s' -dirty ;;
esac
# All done with mercurial
return
fi
# Check for svn and a svn repo.
# obtain svn Version number suffix information of the warehouse 
if rev=`LANG= LC_ALL= LC_MESSAGES=C svn info 2>/dev/null | grep '^Last Changed Rev'`; then
rev=`echo $rev | awk '{print $NF}'`
printf -- '-svn%s' "$rev"
# All done with svn
return
fi
}

use bash Judge sentence to judge

git rev-parse --verify --short

To determine whether the present is git Version library management , Then output a short version Library HEAD revision Short code of .

git rev-parse --verify --short HEAD 2>/dev/null

The key is the execution result of the following statement

git describe --exact-match

This sentence describes the current tag identification . without tag It's empty , So the whole if The sentence is true , It's going to go on , Below echo "+", This will output a... In the version number + Number .

If we're in the repository

git tag -a -m "v0.1" v0.1

then , We're executing git describe --exact-match This sentence , It turns out that the output is ours tag identification . that if There is no sentence , Won't echo "+" 了 .

Keep looking at the code above , If there is uncommitted code , printf -dirty It was carried out in the place of git diff The inspection of , That is to say, I have revised , No uploaded files . So basically, all the reasons have been found out , After I upload the file , again make prepare after , Generated kernel.release Sure enough .

Conclusion , linux The management of versions is quite strict , This also makes us in the code management must be strict with themselves , For example, before the release , First check if there are any files that have been modified to upload , Then we should git Type A in the version library tag.

If the code belongs to git management

I hit tag, Then add tag Related characters
- If tag It's just a simple marker , such as 4.14-rc8 Then skip , Because this information is already from the front makefile We got
- If tag There are other suffixes , such as v2.6.30-rc5-302-g72357d5, Print them out
There was no fight tag, Then add log character
For example, the latest commit yes

commit cdebe039ded3e7fcd00c6e5603a878b14d7e564e

Then compile the file include/config/kernel.release The content is 4.14.0-rc8-gcdebe03 According to the parameters passed before

If there is no definition CONFIG_LOCALVERSION_AUTO and LOCALVERSION, scm_version The function will pass through --short The parameter version number is followed by "+" Number .
```
if $short; then
echo "+"
return
fi
```

2.4 summary

2.4.1 Set the version number

Script script/setlocalversion Read the version number information in

# localversion* files in the build and source directory
res="$(collect_files localversion*)"
if test ! "$srctree" -ef .; then
res="$res$(collect_files "$srctree"/localversion*)"
fi
# CONFIG_LOCALVERSION and LOCALVERSION (if set)
res="${res}${CONFIG_LOCALVERSION}${LOCALVERSION}"

It can be seen from this that , If you want to add characters to the version number , There are several ways :

Use LOCALVERSION Variable ( Or on the command line , Or add it as an environment variable )
Add files to the root of the kernel source code localversion The content of the file will be automatically added to the version number . Create locally Add... To the file
Definition CONFIG_LOCALVERSION Variable
How to add characters to the version number

LOCALVERSION Variables can be defined on the command line :

make LOCALVERSION=.44 include/config/kernel.release

Or add it as an environment variable

export LOCALVERSION=.44
make include/config/kernel.release

The current kernel version is 4.14.0-rc8, If there are files in the root directory of the source code localversion( Its content is .33), Also used. LOCALVERSION Variable (make When you specify ), It also defines CONFIG_LOCALVERSION=".XYZ".

make LOCALVERSION=.44 include/config/kernel.release

Right now 4.14-rc8 The kernel of , include/config/kernel.release The content is 4.14-rc8.33.XYZ.55.

You can see the order of the three characters added

file localversion The content comes first , And then there was CONFIG_LOCALVERSION Value , And finally LOCALVERSION Value

namely

2.4.2 The acquisition of suffix information

If CONFIG_LOCALVERSION_AUTO = y This program will go through scm_version function ( Without parameters ) Configure local version number suffix information . The suffix information is usually the version number of the hosting repository , such as git tag/commit etc.
If CONFIG_LOCALVERSION_AUTO Not set , and LOVALVERSION It's empty , be "${LOCALVERSION+set}" != "set", So called scm_version --short Will add a... At the end + Number .

in addition , About scripts/setlocalversion file .

stay `scripts/setlocalversion In file , You can use echo “aaa” >&2 To output and display relevant information , for example ：
echo “LOCALVERSION=${LOCALVERSION}” >&2

It needs careful attention

Use modinfo You can view the compiled ko The kernel version number of the file
Use uname perhaps cat /proc/version The kernel version number can be viewed on the target system .

You can see kernel Files generated by the compilation process include/config/kernel.release perhaps include/generated/utsrelease.h, Determine the version number of the compiled kernel .

2.4.3 verification

LOCALVERSION You can add suffix information after the version number , If we redefine CONFIG_LOCALVERSION_AUTO, It will be added at the end git Version number is suffix information
Does not define CONFIG_LOCALVERSION_AUTO Will not show git Warehouse information , If at this time LOCALVERSION The variable definition is undefined , Will add “+”.

here scm_version –short Added a “+” Number

cat .config | grep -E "CONFIG_LOCALVERSION"
make kernelrelease

As long as it's defined LOCALVERSION Even if it is defined as NULL, No additional “+”

make LOCALVERSION= kernelrelease
make LOCALVERSION="" kernelrelease

You will not add “+” Number

3 solve

LOCALVERSION You can add suffix information after the version number , If we redefine CONFIG_LOCALVERSION_AUTO, It will be added at the end git Version number is suffix information .
Does not define CONFIG_LOCALVERSION_AUTO Will not show git Warehouse information , If at this time LOCALVERSION The variable definition is undefined , Will add “+”.
If you don't want to add a suffix , I don't want to have "+" Number : Does not define CONFIG_LOCALVERSION_AUTO, take LOCALVERSION The variable definition is empty : LOCALVERSION=.
As long as it's defined LOCALVERSION, Then there will be no additional “+” The no.

4 Reference material

towards linux Add characters to kernel version number / Why is it sometimes added automatically + Number

towards linux Add characters to kernel version number / Why is it sometimes added automatically ”+” Number or ”xxx-dirty”

towards linux Add characters to kernel version number / Why is it sometimes added automatically “+” Number

Get rid of linux The kernel version number is automatically added “+” Number

LINUX KERNEL A plus sign is added to the version generated by compilation ”+”

Ben Bowen was written by Cheng Jian (gatieme) A literary creation , Link to the original text :

http://blog.csdn.net/gatieme

Linux kernel compiles localversion configuration (analyze the '+' number automatically added by kernel version number)