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)        1.62.0           rustc --version
35bindgen (optional)     0.56.0           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
63====================== ===============  ========================================
64
65.. [#f1] Sphinx is needed only to build the Kernel documentation
66
67Kernel compilation
68******************
69
70GCC
71---
72
73The gcc version requirements may vary depending on the type of CPU in your
74computer.
75
76Clang/LLVM (optional)
77---------------------
78
79The latest formal release of clang and LLVM utils (according to
80`releases.llvm.org <https://releases.llvm.org>`_) are supported for building
81kernels. Older releases aren't guaranteed to work, and we may drop workarounds
82from the kernel that were used to support older versions. Please see additional
83docs on :ref:`Building Linux with Clang/LLVM <kbuild_llvm>`.
84
85Rust (optional)
86---------------
87
88A particular version of the Rust toolchain is required. Newer versions may or
89may not work because the kernel depends on some unstable Rust features, for
90the moment.
91
92Each Rust toolchain comes with several "components", some of which are required
93(like ``rustc``) and some that are optional. The ``rust-src`` component (which
94is optional) needs to be installed to build the kernel. Other components are
95useful for developing.
96
97Please see Documentation/rust/quick-start.rst for instructions on how to
98satisfy the build requirements of Rust support. In particular, the ``Makefile``
99target ``rustavailable`` is useful to check why the Rust toolchain may not
100be detected.
101
102bindgen (optional)
103------------------
104
105``bindgen`` is used to generate the Rust bindings to the C side of the kernel.
106It depends on ``libclang``.
107
108Make
109----
110
111You will need GNU make 3.82 or later to build the kernel.
112
113Bash
114----
115
116Some bash scripts are used for the kernel build.
117Bash 4.2 or newer is needed.
118
119Binutils
120--------
121
122Binutils 2.25 or newer is needed to build the kernel.
123
124pkg-config
125----------
126
127The build system, as of 4.18, requires pkg-config to check for installed
128kconfig tools and to determine flags settings for use in
129'make {g,x}config'.  Previously pkg-config was being used but not
130verified or documented.
131
132Flex
133----
134
135Since Linux 4.16, the build system generates lexical analyzers
136during build.  This requires flex 2.5.35 or later.
137
138
139Bison
140-----
141
142Since Linux 4.16, the build system generates parsers
143during build.  This requires bison 2.0 or later.
144
145pahole:
146-------
147
148Since Linux 5.2, if CONFIG_DEBUG_INFO_BTF is selected, the build system
149generates BTF (BPF Type Format) from DWARF in vmlinux, a bit later from kernel
150modules as well.  This requires pahole v1.16 or later.
151
152It is found in the 'dwarves' or 'pahole' distro packages or from
153https://fedorapeople.org/~acme/dwarves/.
154
155Perl
156----
157
158You will need perl 5 and the following modules: ``Getopt::Long``,
159``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel.
160
161BC
162--
163
164You will need bc to build kernels 3.10 and higher
165
166
167OpenSSL
168-------
169
170Module signing and external certificate handling use the OpenSSL program and
171crypto library to do key creation and signature generation.
172
173You will need openssl to build kernels 3.7 and higher if module signing is
174enabled.  You will also need openssl development packages to build kernels 4.3
175and higher.
176
177
178System utilities
179****************
180
181Architectural changes
182---------------------
183
184DevFS has been obsoleted in favour of udev
185(https://www.kernel.org/pub/linux/utils/kernel/hotplug/)
186
18732-bit UID support is now in place.  Have fun!
188
189Linux documentation for functions is transitioning to inline
190documentation via specially-formatted comments near their
191definitions in the source.  These comments can be combined with ReST
192files the Documentation/ directory to make enriched documentation, which can
193then be converted to PostScript, HTML, LaTex, ePUB and PDF files.
194In order to convert from ReST format to a format of your choice, you'll need
195Sphinx.
196
197Util-linux
198----------
199
200New versions of util-linux provide ``fdisk`` support for larger disks,
201support new options to mount, recognize more supported partition
202types, have a fdformat which works with 2.4 kernels, and similar goodies.
203You'll probably want to upgrade.
204
205Ksymoops
206--------
207
208If the unthinkable happens and your kernel oopses, you may need the
209ksymoops tool to decode it, but in most cases you don't.
210It is generally preferred to build the kernel with ``CONFIG_KALLSYMS`` so
211that it produces readable dumps that can be used as-is (this also
212produces better output than ksymoops).  If for some reason your kernel
213is not build with ``CONFIG_KALLSYMS`` and you have no way to rebuild and
214reproduce the Oops with that option, then you can still decode that Oops
215with ksymoops.
216
217Mkinitrd
218--------
219
220These changes to the ``/lib/modules`` file tree layout also require that
221mkinitrd be upgraded.
222
223E2fsprogs
224---------
225
226The latest version of ``e2fsprogs`` fixes several bugs in fsck and
227debugfs.  Obviously, it's a good idea to upgrade.
228
229JFSutils
230--------
231
232The ``jfsutils`` package contains the utilities for the file system.
233The following utilities are available:
234
235- ``fsck.jfs`` - initiate replay of the transaction log, and check
236  and repair a JFS formatted partition.
237
238- ``mkfs.jfs`` - create a JFS formatted partition.
239
240- other file system utilities are also available in this package.
241
242Reiserfsprogs
243-------------
244
245The reiserfsprogs package should be used for reiserfs-3.6.x
246(Linux kernels 2.4.x). It is a combined package and contains working
247versions of ``mkreiserfs``, ``resize_reiserfs``, ``debugreiserfs`` and
248``reiserfsck``. These utils work on both i386 and alpha platforms.
249
250Xfsprogs
251--------
252
253The latest version of ``xfsprogs`` contains ``mkfs.xfs``, ``xfs_db``, and the
254``xfs_repair`` utilities, among others, for the XFS filesystem.  It is
255architecture independent and any version from 2.0.0 onward should
256work correctly with this version of the XFS kernel code (2.6.0 or
257later is recommended, due to some significant improvements).
258
259PCMCIAutils
260-----------
261
262PCMCIAutils replaces ``pcmcia-cs``. It properly sets up
263PCMCIA sockets at system startup and loads the appropriate modules
264for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
265subsystem is used.
266
267Quota-tools
268-----------
269
270Support for 32 bit uid's and gid's is required if you want to use
271the newer version 2 quota format.  Quota-tools version 3.07 and
272newer has this support.  Use the recommended version or newer
273from the table above.
274
275Intel IA32 microcode
276--------------------
277
278A driver has been added to allow updating of Intel IA32 microcode,
279accessible as a normal (misc) character device.  If you are not using
280udev you may need to::
281
282  mkdir /dev/cpu
283  mknod /dev/cpu/microcode c 10 184
284  chmod 0644 /dev/cpu/microcode
285
286as root before you can use this.  You'll probably also want to
287get the user-space microcode_ctl utility to use with this.
288
289udev
290----
291
292``udev`` is a userspace application for populating ``/dev`` dynamically with
293only entries for devices actually present. ``udev`` replaces the basic
294functionality of devfs, while allowing persistent device naming for
295devices.
296
297FUSE
298----
299
300Needs libfuse 2.4.0 or later.  Absolute minimum is 2.3.0 but mount
301options ``direct_io`` and ``kernel_cache`` won't work.
302
303Networking
304**********
305
306General changes
307---------------
308
309If you have advanced network configuration needs, you should probably
310consider using the network tools from ip-route2.
311
312Packet Filter / NAT
313-------------------
314The packet filtering and NAT code uses the same tools like the previous 2.4.x
315kernel series (iptables).  It still includes backwards-compatibility modules
316for 2.2.x-style ipchains and 2.0.x-style ipfwadm.
317
318PPP
319---
320
321The PPP driver has been restructured to support multilink and to
322enable it to operate over diverse media layers.  If you use PPP,
323upgrade pppd to at least 2.4.0.
324
325If you are not using udev, you must have the device file /dev/ppp
326which can be made by::
327
328  mknod /dev/ppp c 108 0
329
330as root.
331
332NFS-utils
333---------
334
335In ancient (2.4 and earlier) kernels, the nfs server needed to know
336about any client that expected to be able to access files via NFS.  This
337information would be given to the kernel by ``mountd`` when the client
338mounted the filesystem, or by ``exportfs`` at system startup.  exportfs
339would take information about active clients from ``/var/lib/nfs/rmtab``.
340
341This approach is quite fragile as it depends on rmtab being correct
342which is not always easy, particularly when trying to implement
343fail-over.  Even when the system is working well, ``rmtab`` suffers from
344getting lots of old entries that never get removed.
345
346With modern kernels we have the option of having the kernel tell mountd
347when it gets a request from an unknown host, and mountd can give
348appropriate export information to the kernel.  This removes the
349dependency on ``rmtab`` and means that the kernel only needs to know about
350currently active clients.
351
352To enable this new functionality, you need to::
353
354  mount -t nfsd nfsd /proc/fs/nfsd
355
356before running exportfs or mountd.  It is recommended that all NFS
357services be protected from the internet-at-large by a firewall where
358that is possible.
359
360mcelog
361------
362
363On x86 kernels the mcelog utility is needed to process and log machine check
364events when ``CONFIG_X86_MCE`` is enabled. Machine check events are errors
365reported by the CPU. Processing them is strongly encouraged.
366
367Kernel documentation
368********************
369
370Sphinx
371------
372
373Please see :ref:`sphinx_install` in :ref:`Documentation/doc-guide/sphinx.rst <sphinxdoc>`
374for details about Sphinx requirements.
375
376rustdoc
377-------
378
379``rustdoc`` is used to generate the documentation for Rust code. Please see
380Documentation/rust/general-information.rst for more information.
381
382Getting updated software
383========================
384
385Kernel compilation
386******************
387
388gcc
389---
390
391- <ftp://ftp.gnu.org/gnu/gcc/>
392
393Clang/LLVM
394----------
395
396- :ref:`Getting LLVM <getting_llvm>`.
397
398Rust
399----
400
401- Documentation/rust/quick-start.rst.
402
403bindgen
404-------
405
406- Documentation/rust/quick-start.rst.
407
408Make
409----
410
411- <ftp://ftp.gnu.org/gnu/make/>
412
413Bash
414----
415
416- <ftp://ftp.gnu.org/gnu/bash/>
417
418Binutils
419--------
420
421- <https://www.kernel.org/pub/linux/devel/binutils/>
422
423Flex
424----
425
426- <https://github.com/westes/flex/releases>
427
428Bison
429-----
430
431- <ftp://ftp.gnu.org/gnu/bison/>
432
433OpenSSL
434-------
435
436- <https://www.openssl.org/>
437
438System utilities
439****************
440
441Util-linux
442----------
443
444- <https://www.kernel.org/pub/linux/utils/util-linux/>
445
446Kmod
447----
448
449- <https://www.kernel.org/pub/linux/utils/kernel/kmod/>
450- <https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git>
451
452Ksymoops
453--------
454
455- <https://www.kernel.org/pub/linux/utils/kernel/ksymoops/v2.4/>
456
457Mkinitrd
458--------
459
460- <https://code.launchpad.net/initrd-tools/main>
461
462E2fsprogs
463---------
464
465- <https://www.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/>
466- <https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/>
467
468JFSutils
469--------
470
471- <http://jfs.sourceforge.net/>
472
473Reiserfsprogs
474-------------
475
476- <https://git.kernel.org/pub/scm/linux/kernel/git/jeffm/reiserfsprogs.git/>
477
478Xfsprogs
479--------
480
481- <https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git>
482- <https://www.kernel.org/pub/linux/utils/fs/xfs/xfsprogs/>
483
484Pcmciautils
485-----------
486
487- <https://www.kernel.org/pub/linux/utils/kernel/pcmcia/>
488
489Quota-tools
490-----------
491
492- <http://sourceforge.net/projects/linuxquota/>
493
494
495Intel P6 microcode
496------------------
497
498- <https://downloadcenter.intel.com/>
499
500udev
501----
502
503- <https://www.freedesktop.org/software/systemd/man/udev.html>
504
505FUSE
506----
507
508- <https://github.com/libfuse/libfuse/releases>
509
510mcelog
511------
512
513- <http://www.mcelog.org/>
514
515cpio
516----
517
518- <https://www.gnu.org/software/cpio/>
519
520Networking
521**********
522
523PPP
524---
525
526- <https://download.samba.org/pub/ppp/>
527- <https://git.ozlabs.org/?p=ppp.git>
528- <https://github.com/paulusmack/ppp/>
529
530NFS-utils
531---------
532
533- <http://sourceforge.net/project/showfiles.php?group_id=14>
534
535Iptables
536--------
537
538- <https://netfilter.org/projects/iptables/index.html>
539
540Ip-route2
541---------
542
543- <https://www.kernel.org/pub/linux/utils/net/iproute2/>
544
545OProfile
546--------
547
548- <http://oprofile.sf.net/download/>
549
550NFS-Utils
551---------
552
553- <http://nfs.sourceforge.net/>
554
555Kernel documentation
556********************
557
558Sphinx
559------
560
561- <https://www.sphinx-doc.org/>
562