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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) 13.0.1 clang --version
34Rust (optional) 1.78.0 rustc --version
35bindgen (optional) 0.65.1 bindgen --version
36GNU make 4.0 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 btrfs --version
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
65mkimage (optional) 2017.01 mkimage --version
66Python (optional) 3.5.x python3 --version
67GNU AWK (optional) 5.1.0 gawk --version
68====================== =============== ========================================
69
70.. [#f1] Sphinx is needed only to build the Kernel documentation
71
72Kernel compilation
73******************
74
75GCC
76---
77
78The gcc version requirements may vary depending on the type of CPU in your
79computer.
80
81Clang/LLVM (optional)
82---------------------
83
84The latest formal release of clang and LLVM utils (according to
85`releases.llvm.org <https://releases.llvm.org>`_) are supported for building
86kernels. Older releases aren't guaranteed to work, and we may drop workarounds
87from the kernel that were used to support older versions. Please see additional
88docs on :ref:`Building Linux with Clang/LLVM <kbuild_llvm>`.
89
90Rust (optional)
91---------------
92
93A recent version of the Rust compiler is required.
94
95Please see Documentation/rust/quick-start.rst for instructions on how to
96satisfy the build requirements of Rust support. In particular, the ``Makefile``
97target ``rustavailable`` is useful to check why the Rust toolchain may not
98be detected.
99
100bindgen (optional)
101------------------
102
103``bindgen`` is used to generate the Rust bindings to the C side of the kernel.
104It depends on ``libclang``.
105
106Make
107----
108
109You will need GNU make 4.0 or later to build the kernel.
110
111Bash
112----
113
114Some bash scripts are used for the kernel build.
115Bash 4.2 or newer is needed.
116
117Binutils
118--------
119
120Binutils 2.25 or newer is needed to build the kernel.
121
122pkg-config
123----------
124
125The build system, as of 4.18, requires pkg-config to check for installed
126kconfig tools and to determine flags settings for use in
127'make {g,x}config'. Previously pkg-config was being used but not
128verified or documented.
129
130Flex
131----
132
133Since Linux 4.16, the build system generates lexical analyzers
134during build. This requires flex 2.5.35 or later.
135
136
137Bison
138-----
139
140Since Linux 4.16, the build system generates parsers
141during build. This requires bison 2.0 or later.
142
143pahole
144------
145
146Since Linux 5.2, if CONFIG_DEBUG_INFO_BTF is selected, the build system
147generates BTF (BPF Type Format) from DWARF in vmlinux, a bit later from kernel
148modules as well. This requires pahole v1.16 or later.
149
150It is found in the 'dwarves' or 'pahole' distro packages or from
151https://fedorapeople.org/~acme/dwarves/.
152
153Perl
154----
155
156You will need perl 5 and the following modules: ``Getopt::Long``,
157``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel.
158
159BC
160--
161
162You will need bc to build kernels 3.10 and higher
163
164
165OpenSSL
166-------
167
168Module signing and external certificate handling use the OpenSSL program and
169crypto library to do key creation and signature generation.
170
171You will need openssl to build kernels 3.7 and higher if module signing is
172enabled. You will also need openssl development packages to build kernels 4.3
173and higher.
174
175Tar
176---
177
178GNU tar is needed if you want to enable access to the kernel headers via sysfs
179(CONFIG_IKHEADERS).
180
181gtags / GNU GLOBAL (optional)
182-----------------------------
183
184The kernel build requires GNU GLOBAL version 6.6.5 or later to generate
185tag files through ``make gtags``. This is due to its use of the gtags
186``-C (--directory)`` flag.
187
188mkimage
189-------
190
191This tool is used when building a Flat Image Tree (FIT), commonly used on ARM
192platforms. The tool is available via the ``u-boot-tools`` package or can be
193built from the U-Boot source code. See the instructions at
194https://docs.u-boot.org/en/latest/build/tools.html#building-tools-for-linux
195
196GNU AWK
197-------
198
199GNU AWK is needed if you want kernel builds to generate address range data for
200builtin modules (CONFIG_BUILTIN_MODULE_RANGES).
201
202System utilities
203****************
204
205Architectural changes
206---------------------
207
208DevFS has been obsoleted in favour of udev
209(https://www.kernel.org/pub/linux/utils/kernel/hotplug/)
210
21132-bit UID support is now in place. Have fun!
212
213Linux documentation for functions is transitioning to inline
214documentation via specially-formatted comments near their
215definitions in the source. These comments can be combined with ReST
216files the Documentation/ directory to make enriched documentation, which can
217then be converted to PostScript, HTML, LaTex, ePUB and PDF files.
218In order to convert from ReST format to a format of your choice, you'll need
219Sphinx.
220
221Util-linux
222----------
223
224New versions of util-linux provide ``fdisk`` support for larger disks,
225support new options to mount, recognize more supported partition
226types, and similar goodies.
227You'll probably want to upgrade.
228
229Ksymoops
230--------
231
232If the unthinkable happens and your kernel oopses, you may need the
233ksymoops tool to decode it, but in most cases you don't.
234It is generally preferred to build the kernel with ``CONFIG_KALLSYMS`` so
235that it produces readable dumps that can be used as-is (this also
236produces better output than ksymoops). If for some reason your kernel
237is not build with ``CONFIG_KALLSYMS`` and you have no way to rebuild and
238reproduce the Oops with that option, then you can still decode that Oops
239with ksymoops.
240
241Mkinitrd
242--------
243
244These changes to the ``/lib/modules`` file tree layout also require that
245mkinitrd be upgraded.
246
247E2fsprogs
248---------
249
250The latest version of ``e2fsprogs`` fixes several bugs in fsck and
251debugfs. Obviously, it's a good idea to upgrade.
252
253JFSutils
254--------
255
256The ``jfsutils`` package contains the utilities for the file system.
257The following utilities are available:
258
259- ``fsck.jfs`` - initiate replay of the transaction log, and check
260 and repair a JFS formatted partition.
261
262- ``mkfs.jfs`` - create a JFS formatted partition.
263
264- other file system utilities are also available in this package.
265
266Reiserfsprogs
267-------------
268
269The reiserfsprogs package should be used for reiserfs-3.6.x
270(Linux kernels 2.4.x). It is a combined package and contains working
271versions of ``mkreiserfs``, ``resize_reiserfs``, ``debugreiserfs`` and
272``reiserfsck``. These utils work on both i386 and alpha platforms.
273
274Xfsprogs
275--------
276
277The latest version of ``xfsprogs`` contains ``mkfs.xfs``, ``xfs_db``, and the
278``xfs_repair`` utilities, among others, for the XFS filesystem. It is
279architecture independent and any version from 2.0.0 onward should
280work correctly with this version of the XFS kernel code (2.6.0 or
281later is recommended, due to some significant improvements).
282
283PCMCIAutils
284-----------
285
286PCMCIAutils replaces ``pcmcia-cs``. It properly sets up
287PCMCIA sockets at system startup and loads the appropriate modules
288for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
289subsystem is used.
290
291Quota-tools
292-----------
293
294Support for 32 bit uid's and gid's is required if you want to use
295the newer version 2 quota format. Quota-tools version 3.07 and
296newer has this support. Use the recommended version or newer
297from the table above.
298
299Intel IA32 microcode
300--------------------
301
302A driver has been added to allow updating of Intel IA32 microcode,
303accessible as a normal (misc) character device. If you are not using
304udev you may need to::
305
306 mkdir /dev/cpu
307 mknod /dev/cpu/microcode c 10 184
308 chmod 0644 /dev/cpu/microcode
309
310as root before you can use this. You'll probably also want to
311get the user-space microcode_ctl utility to use with this.
312
313udev
314----
315
316``udev`` is a userspace application for populating ``/dev`` dynamically with
317only entries for devices actually present. ``udev`` replaces the basic
318functionality of devfs, while allowing persistent device naming for
319devices.
320
321FUSE
322----
323
324Needs libfuse 2.4.0 or later. Absolute minimum is 2.3.0 but mount
325options ``direct_io`` and ``kernel_cache`` won't work.
326
327Networking
328**********
329
330General changes
331---------------
332
333If you have advanced network configuration needs, you should probably
334consider using the network tools from ip-route2.
335
336Packet Filter / NAT
337-------------------
338The packet filtering and NAT code uses the same tools like the previous 2.4.x
339kernel series (iptables). It still includes backwards-compatibility modules
340for 2.2.x-style ipchains and 2.0.x-style ipfwadm.
341
342PPP
343---
344
345The PPP driver has been restructured to support multilink and to
346enable it to operate over diverse media layers. If you use PPP,
347upgrade pppd to at least 2.4.0.
348
349If you are not using udev, you must have the device file /dev/ppp
350which can be made by::
351
352 mknod /dev/ppp c 108 0
353
354as root.
355
356NFS-utils
357---------
358
359In ancient (2.4 and earlier) kernels, the nfs server needed to know
360about any client that expected to be able to access files via NFS. This
361information would be given to the kernel by ``mountd`` when the client
362mounted the filesystem, or by ``exportfs`` at system startup. exportfs
363would take information about active clients from ``/var/lib/nfs/rmtab``.
364
365This approach is quite fragile as it depends on rmtab being correct
366which is not always easy, particularly when trying to implement
367fail-over. Even when the system is working well, ``rmtab`` suffers from
368getting lots of old entries that never get removed.
369
370With modern kernels we have the option of having the kernel tell mountd
371when it gets a request from an unknown host, and mountd can give
372appropriate export information to the kernel. This removes the
373dependency on ``rmtab`` and means that the kernel only needs to know about
374currently active clients.
375
376To enable this new functionality, you need to::
377
378 mount -t nfsd nfsd /proc/fs/nfsd
379
380before running exportfs or mountd. It is recommended that all NFS
381services be protected from the internet-at-large by a firewall where
382that is possible.
383
384mcelog
385------
386
387On x86 kernels the mcelog utility is needed to process and log machine check
388events when ``CONFIG_X86_MCE`` is enabled. Machine check events are errors
389reported by the CPU. Processing them is strongly encouraged.
390
391Kernel documentation
392********************
393
394Sphinx
395------
396
397Please see :ref:`sphinx_install` in :ref:`Documentation/doc-guide/sphinx.rst <sphinxdoc>`
398for details about Sphinx requirements.
399
400rustdoc
401-------
402
403``rustdoc`` is used to generate the documentation for Rust code. Please see
404Documentation/rust/general-information.rst for more information.
405
406Getting updated software
407========================
408
409Kernel compilation
410******************
411
412gcc
413---
414
415- <ftp://ftp.gnu.org/gnu/gcc/>
416
417Clang/LLVM
418----------
419
420- :ref:`Getting LLVM <getting_llvm>`.
421
422Rust
423----
424
425- Documentation/rust/quick-start.rst.
426
427bindgen
428-------
429
430- Documentation/rust/quick-start.rst.
431
432Make
433----
434
435- <ftp://ftp.gnu.org/gnu/make/>
436
437Bash
438----
439
440- <ftp://ftp.gnu.org/gnu/bash/>
441
442Binutils
443--------
444
445- <https://www.kernel.org/pub/linux/devel/binutils/>
446
447Flex
448----
449
450- <https://github.com/westes/flex/releases>
451
452Bison
453-----
454
455- <ftp://ftp.gnu.org/gnu/bison/>
456
457OpenSSL
458-------
459
460- <https://www.openssl.org/>
461
462System utilities
463****************
464
465Util-linux
466----------
467
468- <https://www.kernel.org/pub/linux/utils/util-linux/>
469
470Kmod
471----
472
473- <https://www.kernel.org/pub/linux/utils/kernel/kmod/>
474- <https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git>
475
476Ksymoops
477--------
478
479- <https://www.kernel.org/pub/linux/utils/kernel/ksymoops/v2.4/>
480
481Mkinitrd
482--------
483
484- <https://code.launchpad.net/initrd-tools/main>
485
486E2fsprogs
487---------
488
489- <https://www.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/>
490- <https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/>
491
492JFSutils
493--------
494
495- <https://jfs.sourceforge.net/>
496
497Reiserfsprogs
498-------------
499
500- <https://git.kernel.org/pub/scm/linux/kernel/git/jeffm/reiserfsprogs.git/>
501
502Xfsprogs
503--------
504
505- <https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git>
506- <https://www.kernel.org/pub/linux/utils/fs/xfs/xfsprogs/>
507
508Pcmciautils
509-----------
510
511- <https://www.kernel.org/pub/linux/utils/kernel/pcmcia/>
512
513Quota-tools
514-----------
515
516- <https://sourceforge.net/projects/linuxquota/>
517
518
519Intel P6 microcode
520------------------
521
522- <https://downloadcenter.intel.com/>
523
524udev
525----
526
527- <https://www.freedesktop.org/software/systemd/man/udev.html>
528
529FUSE
530----
531
532- <https://github.com/libfuse/libfuse/releases>
533
534mcelog
535------
536
537- <https://www.mcelog.org/>
538
539cpio
540----
541
542- <https://www.gnu.org/software/cpio/>
543
544Networking
545**********
546
547PPP
548---
549
550- <https://download.samba.org/pub/ppp/>
551- <https://git.ozlabs.org/?p=ppp.git>
552- <https://github.com/paulusmack/ppp/>
553
554NFS-utils
555---------
556
557- <https://sourceforge.net/project/showfiles.php?group_id=14>
558- <https://nfs.sourceforge.net/>
559
560Iptables
561--------
562
563- <https://netfilter.org/projects/iptables/index.html>
564
565Ip-route2
566---------
567
568- <https://www.kernel.org/pub/linux/utils/net/iproute2/>
569
570OProfile
571--------
572
573- <https://oprofile.sf.net/download/>
574
575Kernel documentation
576********************
577
578Sphinx
579------
580
581- <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 4.x kernels.
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 4.9 gcc --version
33GNU make 3.81 make --version
34binutils 2.23 ld -v
35flex 2.5.35 flex --version
36bison 2.0 bison --version
37util-linux 2.10o fdformat --version
38kmod 13 depmod -V
39e2fsprogs 1.41.4 e2fsck -V
40jfsutils 1.1.3 fsck.jfs -V
41reiserfsprogs 3.6.3 reiserfsck -V
42xfsprogs 2.6.0 xfs_db -V
43squashfs-tools 4.0 mksquashfs -version
44btrfs-progs 0.18 btrfsck
45pcmciautils 004 pccardctl -V
46quota-tools 3.09 quota -V
47PPP 2.4.0 pppd --version
48nfs-utils 1.0.5 showmount --version
49procps 3.2.0 ps --version
50oprofile 0.9 oprofiled --version
51udev 081 udevd --version
52grub 0.93 grub --version || grub-install --version
53mcelog 0.6 mcelog --version
54iptables 1.4.2 iptables -V
55openssl & libcrypto 1.0.0 openssl version
56bc 1.06.95 bc --version
57Sphinx\ [#f1]_ 1.3 sphinx-build --version
58====================== =============== ========================================
59
60.. [#f1] Sphinx is needed only to build the Kernel documentation
61
62Kernel compilation
63******************
64
65GCC
66---
67
68The gcc version requirements may vary depending on the type of CPU in your
69computer.
70
71Make
72----
73
74You will need GNU make 3.81 or later to build the kernel.
75
76Binutils
77--------
78
79Binutils 2.23 or newer is needed to build the kernel.
80
81pkg-config
82----------
83
84The build system, as of 4.18, requires pkg-config to check for installed
85kconfig tools and to determine flags settings for use in
86'make {g,x}config'. Previously pkg-config was being used but not
87verified or documented.
88
89Flex
90----
91
92Since Linux 4.16, the build system generates lexical analyzers
93during build. This requires flex 2.5.35 or later.
94
95
96Bison
97-----
98
99Since Linux 4.16, the build system generates parsers
100during build. This requires bison 2.0 or later.
101
102Perl
103----
104
105You will need perl 5 and the following modules: ``Getopt::Long``,
106``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel.
107
108BC
109--
110
111You will need bc to build kernels 3.10 and higher
112
113
114OpenSSL
115-------
116
117Module signing and external certificate handling use the OpenSSL program and
118crypto library to do key creation and signature generation.
119
120You will need openssl to build kernels 3.7 and higher if module signing is
121enabled. You will also need openssl development packages to build kernels 4.3
122and higher.
123
124
125System utilities
126****************
127
128Architectural changes
129---------------------
130
131DevFS has been obsoleted in favour of udev
132(https://www.kernel.org/pub/linux/utils/kernel/hotplug/)
133
13432-bit UID support is now in place. Have fun!
135
136Linux documentation for functions is transitioning to inline
137documentation via specially-formatted comments near their
138definitions in the source. These comments can be combined with ReST
139files the Documentation/ directory to make enriched documentation, which can
140then be converted to PostScript, HTML, LaTex, ePUB and PDF files.
141In order to convert from ReST format to a format of your choice, you'll need
142Sphinx.
143
144Util-linux
145----------
146
147New versions of util-linux provide ``fdisk`` support for larger disks,
148support new options to mount, recognize more supported partition
149types, have a fdformat which works with 2.4 kernels, and similar goodies.
150You'll probably want to upgrade.
151
152Ksymoops
153--------
154
155If the unthinkable happens and your kernel oopses, you may need the
156ksymoops tool to decode it, but in most cases you don't.
157It is generally preferred to build the kernel with ``CONFIG_KALLSYMS`` so
158that it produces readable dumps that can be used as-is (this also
159produces better output than ksymoops). If for some reason your kernel
160is not build with ``CONFIG_KALLSYMS`` and you have no way to rebuild and
161reproduce the Oops with that option, then you can still decode that Oops
162with ksymoops.
163
164Mkinitrd
165--------
166
167These changes to the ``/lib/modules`` file tree layout also require that
168mkinitrd be upgraded.
169
170E2fsprogs
171---------
172
173The latest version of ``e2fsprogs`` fixes several bugs in fsck and
174debugfs. Obviously, it's a good idea to upgrade.
175
176JFSutils
177--------
178
179The ``jfsutils`` package contains the utilities for the file system.
180The following utilities are available:
181
182- ``fsck.jfs`` - initiate replay of the transaction log, and check
183 and repair a JFS formatted partition.
184
185- ``mkfs.jfs`` - create a JFS formatted partition.
186
187- other file system utilities are also available in this package.
188
189Reiserfsprogs
190-------------
191
192The reiserfsprogs package should be used for reiserfs-3.6.x
193(Linux kernels 2.4.x). It is a combined package and contains working
194versions of ``mkreiserfs``, ``resize_reiserfs``, ``debugreiserfs`` and
195``reiserfsck``. These utils work on both i386 and alpha platforms.
196
197Xfsprogs
198--------
199
200The latest version of ``xfsprogs`` contains ``mkfs.xfs``, ``xfs_db``, and the
201``xfs_repair`` utilities, among others, for the XFS filesystem. It is
202architecture independent and any version from 2.0.0 onward should
203work correctly with this version of the XFS kernel code (2.6.0 or
204later is recommended, due to some significant improvements).
205
206PCMCIAutils
207-----------
208
209PCMCIAutils replaces ``pcmcia-cs``. It properly sets up
210PCMCIA sockets at system startup and loads the appropriate modules
211for 16-bit PCMCIA devices if the kernel is modularized and the hotplug
212subsystem is used.
213
214Quota-tools
215-----------
216
217Support for 32 bit uid's and gid's is required if you want to use
218the newer version 2 quota format. Quota-tools version 3.07 and
219newer has this support. Use the recommended version or newer
220from the table above.
221
222Intel IA32 microcode
223--------------------
224
225A driver has been added to allow updating of Intel IA32 microcode,
226accessible as a normal (misc) character device. If you are not using
227udev you may need to::
228
229 mkdir /dev/cpu
230 mknod /dev/cpu/microcode c 10 184
231 chmod 0644 /dev/cpu/microcode
232
233as root before you can use this. You'll probably also want to
234get the user-space microcode_ctl utility to use with this.
235
236udev
237----
238
239``udev`` is a userspace application for populating ``/dev`` dynamically with
240only entries for devices actually present. ``udev`` replaces the basic
241functionality of devfs, while allowing persistent device naming for
242devices.
243
244FUSE
245----
246
247Needs libfuse 2.4.0 or later. Absolute minimum is 2.3.0 but mount
248options ``direct_io`` and ``kernel_cache`` won't work.
249
250Networking
251**********
252
253General changes
254---------------
255
256If you have advanced network configuration needs, you should probably
257consider using the network tools from ip-route2.
258
259Packet Filter / NAT
260-------------------
261The packet filtering and NAT code uses the same tools like the previous 2.4.x
262kernel series (iptables). It still includes backwards-compatibility modules
263for 2.2.x-style ipchains and 2.0.x-style ipfwadm.
264
265PPP
266---
267
268The PPP driver has been restructured to support multilink and to
269enable it to operate over diverse media layers. If you use PPP,
270upgrade pppd to at least 2.4.0.
271
272If you are not using udev, you must have the device file /dev/ppp
273which can be made by::
274
275 mknod /dev/ppp c 108 0
276
277as root.
278
279NFS-utils
280---------
281
282In ancient (2.4 and earlier) kernels, the nfs server needed to know
283about any client that expected to be able to access files via NFS. This
284information would be given to the kernel by ``mountd`` when the client
285mounted the filesystem, or by ``exportfs`` at system startup. exportfs
286would take information about active clients from ``/var/lib/nfs/rmtab``.
287
288This approach is quite fragile as it depends on rmtab being correct
289which is not always easy, particularly when trying to implement
290fail-over. Even when the system is working well, ``rmtab`` suffers from
291getting lots of old entries that never get removed.
292
293With modern kernels we have the option of having the kernel tell mountd
294when it gets a request from an unknown host, and mountd can give
295appropriate export information to the kernel. This removes the
296dependency on ``rmtab`` and means that the kernel only needs to know about
297currently active clients.
298
299To enable this new functionality, you need to::
300
301 mount -t nfsd nfsd /proc/fs/nfsd
302
303before running exportfs or mountd. It is recommended that all NFS
304services be protected from the internet-at-large by a firewall where
305that is possible.
306
307mcelog
308------
309
310On x86 kernels the mcelog utility is needed to process and log machine check
311events when ``CONFIG_X86_MCE`` is enabled. Machine check events are errors
312reported by the CPU. Processing them is strongly encouraged.
313
314Kernel documentation
315********************
316
317Sphinx
318------
319
320Please see :ref:`sphinx_install` in :ref:`Documentation/doc-guide/sphinx.rst <sphinxdoc>`
321for details about Sphinx requirements.
322
323Getting updated software
324========================
325
326Kernel compilation
327******************
328
329gcc
330---
331
332- <ftp://ftp.gnu.org/gnu/gcc/>
333
334Make
335----
336
337- <ftp://ftp.gnu.org/gnu/make/>
338
339Binutils
340--------
341
342- <https://www.kernel.org/pub/linux/devel/binutils/>
343
344Flex
345----
346
347- <https://github.com/westes/flex/releases>
348
349Bison
350-----
351
352- <ftp://ftp.gnu.org/gnu/bison/>
353
354OpenSSL
355-------
356
357- <https://www.openssl.org/>
358
359System utilities
360****************
361
362Util-linux
363----------
364
365- <https://www.kernel.org/pub/linux/utils/util-linux/>
366
367Kmod
368----
369
370- <https://www.kernel.org/pub/linux/utils/kernel/kmod/>
371- <https://git.kernel.org/pub/scm/utils/kernel/kmod/kmod.git>
372
373Ksymoops
374--------
375
376- <https://www.kernel.org/pub/linux/utils/kernel/ksymoops/v2.4/>
377
378Mkinitrd
379--------
380
381- <https://code.launchpad.net/initrd-tools/main>
382
383E2fsprogs
384---------
385
386- <https://www.kernel.org/pub/linux/kernel/people/tytso/e2fsprogs/>
387- <https://git.kernel.org/pub/scm/fs/ext2/e2fsprogs.git/>
388
389JFSutils
390--------
391
392- <http://jfs.sourceforge.net/>
393
394Reiserfsprogs
395-------------
396
397- <https://git.kernel.org/pub/scm/linux/kernel/git/jeffm/reiserfsprogs.git/>
398
399Xfsprogs
400--------
401
402- <https://git.kernel.org/pub/scm/fs/xfs/xfsprogs-dev.git>
403- <https://www.kernel.org/pub/linux/utils/fs/xfs/xfsprogs/>
404
405Pcmciautils
406-----------
407
408- <https://www.kernel.org/pub/linux/utils/kernel/pcmcia/>
409
410Quota-tools
411-----------
412
413- <http://sourceforge.net/projects/linuxquota/>
414
415
416Intel P6 microcode
417------------------
418
419- <https://downloadcenter.intel.com/>
420
421udev
422----
423
424- <https://www.freedesktop.org/software/systemd/man/udev.html>
425
426FUSE
427----
428
429- <https://github.com/libfuse/libfuse/releases>
430
431mcelog
432------
433
434- <http://www.mcelog.org/>
435
436Networking
437**********
438
439PPP
440---
441
442- <https://download.samba.org/pub/ppp/>
443- <https://git.ozlabs.org/?p=ppp.git>
444- <https://github.com/paulusmack/ppp/>
445
446NFS-utils
447---------
448
449- <http://sourceforge.net/project/showfiles.php?group_id=14>
450
451Iptables
452--------
453
454- <https://netfilter.org/projects/iptables/index.html>
455
456Ip-route2
457---------
458
459- <https://www.kernel.org/pub/linux/utils/net/iproute2/>
460
461OProfile
462--------
463
464- <http://oprofile.sf.net/download/>
465
466NFS-Utils
467---------
468
469- <http://nfs.sourceforge.net/>
470
471Kernel documentation
472********************
473
474Sphinx
475------
476
477- <https://www.sphinx-doc.org/>