1.. _changes:
2
3Minimal requirements to compile the Kernel
4++++++++++++++++++++++++++++++++++++++++++
5
6Intro
7=====
8
9This document is designed to provide a list of the minimum levels of
10software necessary to run the current kernel version.
11
12This document is originally based on my "Changes" file for 2.0.x kernels
13and therefore owes credit to the same people as that file (Jared Mauch,
14Axel Boldt, Alessandro Sigala, and countless other users all over the
15'net).
16
17Current Minimal Requirements
18****************************
19
20Upgrade to at **least** these software revisions before thinking you've
21encountered a bug!  If you're unsure what version you're currently
22running, the suggested command should tell you.
23
24Again, keep in mind that this list assumes you are already functionally
25running a Linux kernel.  Also, not all tools are necessary on all
26systems; obviously, if you don't have any PC Card hardware, for example,
27you probably needn't concern yourself with pcmciautils.
28
29====================== ===============  ========================================
30        Program        Minimal version       Command to check the version
31====================== ===============  ========================================
32GNU C                  5.1              gcc --version
33Clang/LLVM (optional)  11.0.0           clang --version
34Rust (optional)        1.71.1           rustc --version
35bindgen (optional)     0.65.1           bindgen --version
36GNU make               3.82             make --version
37bash                   4.2              bash --version
38binutils               2.25             ld -v
39flex                   2.5.35           flex --version
40bison                  2.0              bison --version
41pahole                 1.16             pahole --version
42util-linux             2.10o            fdformat --version
43kmod                   13               depmod -V
44e2fsprogs              1.41.4           e2fsck -V
45jfsutils               1.1.3            fsck.jfs -V
46reiserfsprogs          3.6.3            reiserfsck -V
47xfsprogs               2.6.0            xfs_db -V
48squashfs-tools         4.0              mksquashfs -version
49btrfs-progs            0.18             btrfsck
50pcmciautils            004              pccardctl -V
51quota-tools            3.09             quota -V
52PPP                    2.4.0            pppd --version
53nfs-utils              1.0.5            showmount --version
54procps                 3.2.0            ps --version
55udev                   081              udevd --version
56grub                   0.93             grub --version || grub-install --version
57mcelog                 0.6              mcelog --version
58iptables               1.4.2            iptables -V
59openssl & libcrypto    1.0.0            openssl version
60bc                     1.06.95          bc --version
61Sphinx\ [#f1]_         1.7              sphinx-build --version
62cpio                   any              cpio --version
63GNU tar                1.28             tar --version
64gtags (optional)       6.6.5            gtags --version
65====================== ===============  ========================================
66
67.. [#f1] Sphinx is needed only to build the Kernel documentation
68
69Kernel compilation
70******************
71
72GCC
73---
74
75The gcc version requirements may vary depending on the type of CPU in your
76computer.
77
78Clang/LLVM (optional)
79---------------------
80
81The latest formal release of clang and LLVM utils (according to
82`releases.llvm.org <https://releases.llvm.org>`_) are supported for building
83kernels. Older releases aren't guaranteed to work, and we may drop workarounds
84from the kernel that were used to support older versions. Please see additional
85docs on :ref:`Building Linux with Clang/LLVM <kbuild_llvm>`.
86
87Rust (optional)
88---------------
89
90A particular version of the Rust toolchain is required. Newer versions may or
91may not work because the kernel depends on some unstable Rust features, for
92the moment.
93
94Each Rust toolchain comes with several "components", some of which are required
95(like ``rustc``) and some that are optional. The ``rust-src`` component (which
96is optional) needs to be installed to build the kernel. Other components are
97useful for developing.
98
99Please see Documentation/rust/quick-start.rst for instructions on how to
100satisfy the build requirements of Rust support. In particular, the ``Makefile``
101target ``rustavailable`` is useful to check why the Rust toolchain may not
102be detected.
103
104bindgen (optional)
105------------------
106
107``bindgen`` is used to generate the Rust bindings to the C side of the kernel.
108It depends on ``libclang``.
109
110Make
111----
112
113You will need GNU make 3.82 or later to build the kernel.
114
115Bash
116----
117
118Some bash scripts are used for the kernel build.
119Bash 4.2 or newer is needed.
120
121Binutils
122--------
123
124Binutils 2.25 or newer is needed to build the kernel.
125
126pkg-config
127----------
128
129The build system, as of 4.18, requires pkg-config to check for installed
130kconfig tools and to determine flags settings for use in
131'make {g,x}config'.  Previously pkg-config was being used but not
132verified or documented.
133
134Flex
135----
136
137Since Linux 4.16, the build system generates lexical analyzers
138during build.  This requires flex 2.5.35 or later.
139
140
141Bison
142-----
143
144Since Linux 4.16, the build system generates parsers
145during build.  This requires bison 2.0 or later.
146
147pahole:
148-------
149
150Since Linux 5.2, if CONFIG_DEBUG_INFO_BTF is selected, the build system
151generates BTF (BPF Type Format) from DWARF in vmlinux, a bit later from kernel
152modules as well.  This requires pahole v1.16 or later.
153
154It is found in the 'dwarves' or 'pahole' distro packages or from
155https://fedorapeople.org/~acme/dwarves/.
156
157Perl
158----
159
160You will need perl 5 and the following modules: ``Getopt::Long``,
161``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel.
162
163BC
164--
165
166You will need bc to build kernels 3.10 and higher
167
168
169OpenSSL
170-------
171
172Module signing and external certificate handling use the OpenSSL program and
173crypto library to do key creation and signature generation.
174
175You will need openssl to build kernels 3.7 and higher if module signing is
176enabled.  You will also need openssl development packages to build kernels 4.3
177and higher.
178
179Tar
180---
181
182GNU tar is needed if you want to enable access to the kernel headers via sysfs
183(CONFIG_IKHEADERS).
184
185gtags / GNU GLOBAL (optional)
186-----------------------------
187
188The kernel build requires GNU GLOBAL version 6.6.5 or later to generate
189tag files through ``make gtags``.  This is due to its use of the gtags
190``-C (--directory)`` flag.
191
192System utilities
193****************
194
195Architectural changes
196---------------------
197
198DevFS has been obsoleted in favour of udev
199(https://www.kernel.org/pub/linux/utils/kernel/hotplug/)
200
20132-bit UID support is now in place.  Have fun!
202
203Linux documentation for functions is transitioning to inline
204documentation via specially-formatted comments near their
205definitions in the source.  These comments can be combined with ReST
206files the Documentation/ directory to make enriched documentation, which can
207then be converted to PostScript, HTML, LaTex, ePUB and PDF files.
208In order to convert from ReST format to a format of your choice, you'll need
209Sphinx.
210
211Util-linux
212----------
213
214New versions of util-linux provide ``fdisk`` support for larger disks,
215support new options to mount, recognize more supported partition
216types, have a fdformat which works with 2.4 kernels, and similar goodies.
217You'll probably want to upgrade.
218
219Ksymoops
220--------
221
222If the unthinkable happens and your kernel oopses, you may need the
223ksymoops tool to decode it, but in most cases you don't.
224It is generally preferred to build the kernel with ``CONFIG_KALLSYMS`` so
225that it produces readable dumps that can be used as-is (this also
226produces better output than ksymoops).  If for some reason your kernel
227is not build with ``CONFIG_KALLSYMS`` and you have no way to rebuild and
228reproduce the Oops with that option, then you can still decode that Oops
229with ksymoops.
230
231Mkinitrd
232--------
233
234These changes to the ``/lib/modules`` file tree layout also require that
235mkinitrd be upgraded.
236
237E2fsprogs
238---------
239
240The latest version of ``e2fsprogs`` fixes several bugs in fsck and
241debugfs.  Obviously, it's a good idea to upgrade.
242
243JFSutils
244--------
245
246The ``jfsutils`` package contains the utilities for the file system.
247The following utilities are available:
248
249- ``fsck.jfs`` - initiate replay of the transaction log, and check
250  and repair a JFS formatted partition.
251
252- ``mkfs.jfs`` - create a JFS formatted partition.
253
254- other file system utilities are also available in this package.
255
256Reiserfsprogs
257-------------
258
259The reiserfsprogs package should be used for reiserfs-3.6.x
260(Linux kernels 2.4.x). It is a combined package and contains working
261versions of ``mkreiserfs``, ``resize_reiserfs``, ``debugreiserfs`` and
262``reiserfsck``. These utils work on both i386 and alpha platforms.
263
264Xfsprogs
265--------
266
267The latest version of ``xfsprogs`` contains ``mkfs.xfs``, ``xfs_db``, and the
268``xfs_repair`` utilities, among others, for the XFS filesystem.  It is
269architecture independent and any version from 2.0.0 onward should
270work correctly with this version of the XFS kernel code (2.6.0 or
271later is recommended, due to some significant improvements).
272
273PCMCIAutils
274-----------
275
276PCMCIAutils replaces ``pcmcia-cs``. It properly sets up
277PCMCIA sockets at system startup and loads the appropriate modules
278for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
279subsystem is used.
280
281Quota-tools
282-----------
283
284Support for 32 bit uid's and gid's is required if you want to use
285the newer version 2 quota format.  Quota-tools version 3.07 and
286newer has this support.  Use the recommended version or newer
287from the table above.
288
289Intel IA32 microcode
290--------------------
291
292A driver has been added to allow updating of Intel IA32 microcode,
293accessible as a normal (misc) character device.  If you are not using
294udev you may need to::
295
296  mkdir /dev/cpu
297  mknod /dev/cpu/microcode c 10 184
298  chmod 0644 /dev/cpu/microcode
299
300as root before you can use this.  You'll probably also want to
301get the user-space microcode_ctl utility to use with this.
302
303udev
304----
305
306``udev`` is a userspace application for populating ``/dev`` dynamically with
307only entries for devices actually present. ``udev`` replaces the basic
308functionality of devfs, while allowing persistent device naming for
309devices.
310
311FUSE
312----
313
314Needs libfuse 2.4.0 or later.  Absolute minimum is 2.3.0 but mount
315options ``direct_io`` and ``kernel_cache`` won't work.
316
317Networking
318**********
319
320General changes
321---------------
322
323If you have advanced network configuration needs, you should probably
324consider using the network tools from ip-route2.
325
326Packet Filter / NAT
327-------------------
328The packet filtering and NAT code uses the same tools like the previous 2.4.x
329kernel series (iptables).  It still includes backwards-compatibility modules
330for 2.2.x-style ipchains and 2.0.x-style ipfwadm.
331
332PPP
333---
334
335The PPP driver has been restructured to support multilink and to
336enable it to operate over diverse media layers.  If you use PPP,
337upgrade pppd to at least 2.4.0.
338
339If you are not using udev, you must have the device file /dev/ppp
340which can be made by::
341
342  mknod /dev/ppp c 108 0
343
344as root.
345
346NFS-utils
347---------
348
349In ancient (2.4 and earlier) kernels, the nfs server needed to know
350about any client that expected to be able to access files via NFS.  This
351information would be given to the kernel by ``mountd`` when the client
352mounted the filesystem, or by ``exportfs`` at system startup.  exportfs
353would take information about active clients from ``/var/lib/nfs/rmtab``.
354
355This approach is quite fragile as it depends on rmtab being correct
356which is not always easy, particularly when trying to implement
357fail-over.  Even when the system is working well, ``rmtab`` suffers from
358getting lots of old entries that never get removed.
359
360With modern kernels we have the option of having the kernel tell mountd
361when it gets a request from an unknown host, and mountd can give
362appropriate export information to the kernel.  This removes the
363dependency on ``rmtab`` and means that the kernel only needs to know about
364currently active clients.
365
366To enable this new functionality, you need to::
367
368  mount -t nfsd nfsd /proc/fs/nfsd
369
370before running exportfs or mountd.  It is recommended that all NFS
371services be protected from the internet-at-large by a firewall where
372that is possible.
373
374mcelog
375------
376
377On x86 kernels the mcelog utility is needed to process and log machine check
378events when ``CONFIG_X86_MCE`` is enabled. Machine check events are errors
379reported by the CPU. Processing them is strongly encouraged.
380
381Kernel documentation
382********************
383
384Sphinx
385------
386
387Please see :ref:`sphinx_install` in :ref:`Documentation/doc-guide/sphinx.rst <sphinxdoc>`
388for details about Sphinx requirements.
389
390rustdoc
391-------
392
393``rustdoc`` is used to generate the documentation for Rust code. Please see
394Documentation/rust/general-information.rst for more information.
395
396Getting updated software
397========================
398
399Kernel compilation
400******************
401
402gcc
403---
404
405- <ftp://ftp.gnu.org/gnu/gcc/>
406
407Clang/LLVM
408----------
409
410- :ref:`Getting LLVM <getting_llvm>`.
411
412Rust
413----
414
415- Documentation/rust/quick-start.rst.
416
417bindgen
418-------
419
420- Documentation/rust/quick-start.rst.
421
422Make
423----
424
425- <ftp://ftp.gnu.org/gnu/make/>
426
427Bash
428----
429
430- <ftp://ftp.gnu.org/gnu/bash/>
431
432Binutils
433--------
434
435- <https://www.kernel.org/pub/linux/devel/binutils/>
436
437Flex
438----
439
440- <https://github.com/westes/flex/releases>
441
442Bison
443-----
444
445- <ftp://ftp.gnu.org/gnu/bison/>
446
447OpenSSL
448-------
449
450- <https://www.openssl.org/>
451
452System utilities
453****************
454
455Util-linux
456----------
457
458- <https://www.kernel.org/pub/linux/utils/util-linux/>
459
460Kmod
461----
462
463- <https://www.kernel.org/pub/linux/utils/kernel/kmod/>
464- <https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git>
465
466Ksymoops
467--------
468
469- <https://www.kernel.org/pub/linux/utils/kernel/ksymoops/v2.4/>
470
471Mkinitrd
472--------
473
474- <https://code.launchpad.net/initrd-tools/main>
475
476E2fsprogs
477---------
478
479- <https://www.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/>
480- <https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/>
481
482JFSutils
483--------
484
485- <https://jfs.sourceforge.net/>
486
487Reiserfsprogs
488-------------
489
490- <https://git.kernel.org/pub/scm/linux/kernel/git/jeffm/reiserfsprogs.git/>
491
492Xfsprogs
493--------
494
495- <https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git>
496- <https://www.kernel.org/pub/linux/utils/fs/xfs/xfsprogs/>
497
498Pcmciautils
499-----------
500
501- <https://www.kernel.org/pub/linux/utils/kernel/pcmcia/>
502
503Quota-tools
504-----------
505
506- <https://sourceforge.net/projects/linuxquota/>
507
508
509Intel P6 microcode
510------------------
511
512- <https://downloadcenter.intel.com/>
513
514udev
515----
516
517- <https://www.freedesktop.org/software/systemd/man/udev.html>
518
519FUSE
520----
521
522- <https://github.com/libfuse/libfuse/releases>
523
524mcelog
525------
526
527- <https://www.mcelog.org/>
528
529cpio
530----
531
532- <https://www.gnu.org/software/cpio/>
533
534Networking
535**********
536
537PPP
538---
539
540- <https://download.samba.org/pub/ppp/>
541- <https://git.ozlabs.org/?p=ppp.git>
542- <https://github.com/paulusmack/ppp/>
543
544NFS-utils
545---------
546
547- <https://sourceforge.net/project/showfiles.php?group_id=14>
548- <https://nfs.sourceforge.net/>
549
550Iptables
551--------
552
553- <https://netfilter.org/projects/iptables/index.html>
554
555Ip-route2
556---------
557
558- <https://www.kernel.org/pub/linux/utils/net/iproute2/>
559
560OProfile
561--------
562
563- <https://oprofile.sf.net/download/>
564
565Kernel documentation
566********************
567
568Sphinx
569------
570
571- <https://www.sphinx-doc.org/>
572