config-kernel

config-kernel program recursively reads Kconfig files from a given source directory and builds a tree structure of CONFIG_ options. This tree can be traversed to query option's attributes or set/reset them. It can also be used to validate kernel's '.config' file by checking option's value and dependencies.

Kconfig: <#files>, <#options>
 │
 ├── init/Kconfig: 2, 3
 │   ├── CC_VERSION_TEXT
 │   ├── DEFAULT_HOSTNAME
 │   ├── kernel/bpf/Kconfig: 1, 3
 │   │   ├── BPF
 │   │   ├── BPF_JIT
 │   │   ├── BPF_SYSCALL
 │   │   └── preload/kconfig: 0, 2
 │   │       ├── BPF_PRELOAD
 │   │       └── BPF_PRELOAD_UMD
 │   ├── kernel/time: 0, 2
 │   │   ├── LEGACY_TIMER_TICK
 │   │   └── NO_HZ_FULL
 │   └── NAMESPACES
 ├── mm: 0, 4
 │   ├── KSM
 │   ├── MEMORY_HOTPLUG
 │   ├── SLAB
 │   └── SWAP
 └── net: 0, 3
    ├── ETHTOOL_NETLINK
    ├── NET
    └── NETFILTER

Kconfig language based configuration database was introduced in the Linux kernel from version v2.6.0. ie. config-kernel program works with all kernel versions >= v2.6.0. It should work for all projects which use Kconfig files and its syntax to define configuration options. A typical CONFIG entry in a Kconfig file begins with a 'config' keyword on a new line and its attributes on the following lines indented by the tab (\t) character:

config <OPTION_NAME>
<\t>Attribute-1
<\t>Attribute-2
  ...
<\t>Attribute-n

We probably don't need and/or have to maintain complex one-file-per-config-option directory structures.

---

Quick Start

0) Make

   $ dnf install libfl-devel bison-devel
   $ make  <= to build 'configk' binary file.

1) List options in the default hierarchical view:

   $ ./configk ../centos-stream-9/

2) List options in --config file format view:

   $ ./config -C ../linux/

3) List options with --Verbose mode enabled:

   $ ./config -V ../centos-stream-9/

4) List options for a given --srcarch architecture:

   $ ./configk -a powerpc ../centos-stream-9/

5) List a config option with --show:

   $ ./configk -s NO_HZ_FULL ../linux/

6) Check/compare a .config file against the given source tree:

   $ ./configk -c /tmp/config-6.4.8-200.fc38.x86_64 ../centos-stream-9/ 2> /tmp/stderr.log

7) Recursively disable a config option with --disable:

   $ ./configk -d NO_HZ_FULL ../linux/

8) Recursively disable a config option in a given .config file and view output in --config file format:

   $ ./configk -d NO_HZ_FULL -Cc /tmp/config-6.4.8-200.fc38.x86_64 ../linux/ 2> /tmp/stderr.log

9) Recursively enable a config option in a given .config file:

   $ ./configk -e NO_HZ_FULL -c /tmp/config-6.4.8-200.fc38.x86_64 ../linux/ 2> /tmp/stderr.log

10) Recursively toggle a tristate config option between 'y' and 'm' values:

   $ ./configk -c /tmp/config-6.4.8-200.fc38.x86_64  -t TIME_KUNIT_TEST ../linux/ 2> /tmp/stderr.log

11) --Edit and validate a given .config file with an $EDITOR

   $ EDITOR=vim ./configk -E /tmp/config-6.4.8-200.fc38.x86_64 ../linux/

12) Edit file in-place with the --in-place option

   $ ./configk -e CGROUPS -i /tmp/config-6.8.4-200.fc39.x86_64 ../linux/

13) Filter output by a given <string> with --grep switch. By default
    <string> is searched in 'depends on' attribute value; If <string>
    begins with the 's:' prefix, it is searched in the 'select' attribute
    value.

   $ ./configk -g EXT4_FS ../centos-stream-9/
   $ ./configk --grep s:EXT4_FS ../linux/

configk program can check and validate a '.config' configuration file against any given kernel source tree. It supports following options:

Usage: ./configk [OPTIONS] <source-directory>

Options:
  -a --srcarch <arch>        set $SRCARCH variable
  -c --check <file>          check configs against the source tree
  -C --config                show output as a config file
  -d --disable <option>      disable config option
  -e --enable <option>[=val] enable config option
  -E --edit <file>           edit config file with an $EDITOR
  -g --grep <[s:]string>     show config option with matching attribute
  -h --help                  show help
  -i --in-place <file>       edit config file in place
  -s --show <option>         show a config option entry
  -t --toggle <option>       toggle an option between y & m
  -v --version               show version
  -V --verbose               show verbose output

It uses -libfl and -liby libraries from libfl-devel or libfl-static and bison-devel packages.

Examples:

The -s switch shows a config option with its attributes.

$ ./configk -s NO_HZ_FULL ../centos-stream-9/
File   : kernel/time/Kconfig
Config : NO_HZ_FULL
Type   : bool(3)
Default: n
Depends: SMP
       HAVE_CONTEXT_TRACKING_USER
       HAVE_VIRT_CPU_ACCOUNTING_GEN
Select : NO_HZ_COMMON
       RCU_NOCB_CPU
       VIRT_CPU_ACCOUNTING_GEN
       IRQ_WORK
       CPU_ISOLATION
Help   :

    Adaptively try to shutdown the tick whenever possible, even when
    the CPU is running tasks. Typically this requires running a single
    task on the CPU. Chances for running tickless are maximized when
    the task mostly runs in userspace and has few kernel activity.

    You need to fill up the nohz_full boot parameter with the
    desired range of dynticks CPUs to use it. This is implemented at
    the expense of some overhead in user <-> kernel transitions:
    syscalls, exceptions and interrupts.

    By default, without passing the nohz_full parameter, this behaves just
    like NO_HZ_IDLE.

    If you're a distro say Y.

The -d & -e command line options help to recursively disable and enable a given config option.

$ ./configk -e ACPI_PROCESSOR ../linux/
Enable option:
 ACPI_PROCESSOR
   ACPI_PROCESSOR_IDLE
     CPU_IDLE
       CPU_IDLE_GOV_LADDER
       CPU_IDLE_GOV_MENU
   ACPI_CPU_FREQ_PSS
   THERMAL

The --grep option helps to filter output by a given string

$ ./configk -g EXT4_FS ../centos-stream-9/
    fs/ext4/Kconfig: 0, 9
      EXT4_USE_FOR_EXT2
      EXT4_FS_POSIX_ACL
      EXT4_FS_SECURITY
      EXT4_DEBUG
      EXT4_KUNIT_TESTS
Config files: 13
Config options: 9
Config memory: 6.26 MB

$ ./configk --grep s:EXT4_FS ../linux/
    fs/ext4/Kconfig: 0, 9
      EXT3_FS
      EXT3_FS_POSIX_ACL
      EXT3_FS_SECURITY
Config files: 13
Config options: 9
Config memory: 6.64 MB

$ ./configk --grep CGROUPS ../linux/
    net/netfilter/Kconfig: 2, 165
      NETFILTER_XT_MATCH_CGROUP
    net/sched/Kconfig: 0, 87
      NET_CLS_CGROUP
  net/Kconfig: 63, 48
    CGROUP_NET_PRIO
    CGROUP_NET_CLASSID
  lib/Kconfig.debug: 13, 267
    DEBUG_CGROUP_REF
    samples/Kconfig: 1, 43
      SAMPLE_CGROUP
Config files: 92
Config options: 610
Config memory: 6.63 MB

The -c option allows to validate a given '.config' or a kernel configuration template file against a kernel source tree.

$ ./configk -c /tmp/config-6.3.11-200.fc38.x86_64 ../centos-stream-9/
...
configk: option 'INIT_ENV_ARG_LIMIT' has invalid int value: 'x32'
configk: option 'BPF_JIT' has invalid bool value: 'x'
configk: option 'SCHED_MM_CID' not found in the source tree
configk: option 'LD_ORPHAN_WARN_LEVEL' not found in the source tree
...

Kconfig: 14, 0
  scripts/Kconfig.include: 0, 0
  init/Kconfig: 9, 231
    CC_VERSION_TEXT: "(GCC) 13.1.1 20230614 (Red Hat 13.1.1-4)"
    CC_IS_GCC: y
    GCC_VERSION: 130101
    CC_IS_CLANG
    CLANG_VERSION: 0    <= Green entries are selected options
    AS_IS_GNU: y
    AS_IS_LLVM
    AS_VERSION: 23900
    LD_IS_BFD: x        <= Yellow indicates value error
    LD_VERSION: 23900
    LD_IS_LLD
    LLD_VERSION: 0
    CC_CAN_LINK: y
    CC_CAN_LINK_STATIC: y
    CC_HAS_ASM_GOTO     <= Whites are non-selected options
    CC_HAS_ASM_GOTO_OUTPUT: y
    CC_HAS_ASM_GOTO_TIED_OUTPUT: y
    ILLEGAL_POINTER_VALUE: 0kdead0000m0000000
    TOOLS_SUPPORT_RELR
    CC_HAS_ASM_INLINE: y
    CC_HAS_NO_PROFILE_FN_ATTR: y
    PAHOLE_VERSION: 125
    CONSTRUCTORS
    ...