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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/>
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) 1.74.1 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 mount --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]_ 2.4.4 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, 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/>