Minimal requirements to compile the Kernel


This document is designed to provide a list of the minimum levels of software necessary to run the 4.x kernels.

This document is originally based on my “Changes” file for 2.0.x kernels and therefore owes credit to the same people as that file (Jared Mauch, Axel Boldt, Alessandro Sigala, and countless other users all over the ‘net).

Current Minimal Requirements

Upgrade to at least these software revisions before thinking you’ve encountered a bug! If you’re unsure what version you’re currently running, the suggested command should tell you.

Again, keep in mind that this list assumes you are already functionally running a Linux kernel. Also, not all tools are necessary on all systems; obviously, if you don’t have any ISDN hardware, for example, you probably needn’t concern yourself with isdn4k-utils.

Program Minimal version Command to check the version
GNU C 4.6 gcc –version
GNU make 3.81 make –version
binutils 2.20 ld -v
flex 2.5.35 flex –version
bison 2.0 bison –version
util-linux 2.10o fdformat –version
kmod 13 depmod -V
e2fsprogs 1.41.4 e2fsck -V
jfsutils 1.1.3 fsck.jfs -V
reiserfsprogs 3.6.3 reiserfsck -V
xfsprogs 2.6.0 xfs_db -V
squashfs-tools 4.0 mksquashfs -version
btrfs-progs 0.18 btrfsck
pcmciautils 004 pccardctl -V
quota-tools 3.09 quota -V
PPP 2.4.0 pppd –version
isdn4k-utils 3.1pre1 isdnctrl 2>&1|grep version
nfs-utils 1.0.5 showmount –version
procps 3.2.0 ps –version
oprofile 0.9 oprofiled –version
udev 081 udevd –version
grub 0.93 grub –version || grub-install –version
mcelog 0.6 mcelog –version
iptables 1.4.2 iptables -V
openssl & libcrypto 1.0.0 openssl version
bc 1.06.95 bc –version
Sphinx[1] 1.3 sphinx-build –version
[1]Sphinx is needed only to build the Kernel documentation

Kernel compilation


The gcc version requirements may vary depending on the type of CPU in your computer.


You will need GNU make 3.81 or later to build the kernel.


The build system has, as of 4.13, switched to using thin archives (ar T) rather than incremental linking (ld -r) for built-in.a intermediate steps. This requires binutils 2.20 or newer.


The build system, as of 4.18, requires pkg-config to check for installed kconfig tools and to determine flags settings for use in ‘make {g,x}config’. Previously pkg-config was being used but not verified or documented.


Since Linux 4.16, the build system generates lexical analyzers during build. This requires flex 2.5.35 or later.


Since Linux 4.16, the build system generates parsers during build. This requires bison 2.0 or later.


You will need perl 5 and the following modules: Getopt::Long, Getopt::Std, File::Basename, and File::Find to build the kernel.


You will need bc to build kernels 3.10 and higher


Module signing and external certificate handling use the OpenSSL program and crypto library to do key creation and signature generation.

You will need openssl to build kernels 3.7 and higher if module signing is enabled. You will also need openssl development packages to build kernels 4.3 and higher.

System utilities

Architectural changes

DevFS has been obsoleted in favour of udev (

32-bit UID support is now in place. Have fun!

Linux documentation for functions is transitioning to inline documentation via specially-formatted comments near their definitions in the source. These comments can be combined with ReST files the Documentation/ directory to make enriched documentation, which can then be converted to PostScript, HTML, LaTex, ePUB and PDF files. In order to convert from ReST format to a format of your choice, you’ll need Sphinx.


New versions of util-linux provide fdisk support for larger disks, support new options to mount, recognize more supported partition types, have a fdformat which works with 2.4 kernels, and similar goodies. You’ll probably want to upgrade.


If the unthinkable happens and your kernel oopses, you may need the ksymoops tool to decode it, but in most cases you don’t. It is generally preferred to build the kernel with CONFIG_KALLSYMS so that it produces readable dumps that can be used as-is (this also produces better output than ksymoops). If for some reason your kernel is not build with CONFIG_KALLSYMS and you have no way to rebuild and reproduce the Oops with that option, then you can still decode that Oops with ksymoops.


These changes to the /lib/modules file tree layout also require that mkinitrd be upgraded.


The latest version of e2fsprogs fixes several bugs in fsck and debugfs. Obviously, it’s a good idea to upgrade.


The jfsutils package contains the utilities for the file system. The following utilities are available:

  • fsck.jfs - initiate replay of the transaction log, and check and repair a JFS formatted partition.
  • mkfs.jfs - create a JFS formatted partition.
  • other file system utilities are also available in this package.


The reiserfsprogs package should be used for reiserfs-3.6.x (Linux kernels 2.4.x). It is a combined package and contains working versions of mkreiserfs, resize_reiserfs, debugreiserfs and reiserfsck. These utils work on both i386 and alpha platforms.


The latest version of xfsprogs contains mkfs.xfs, xfs_db, and the xfs_repair utilities, among others, for the XFS filesystem. It is architecture independent and any version from 2.0.0 onward should work correctly with this version of the XFS kernel code (2.6.0 or later is recommended, due to some significant improvements).


PCMCIAutils replaces pcmcia-cs. It properly sets up PCMCIA sockets at system startup and loads the appropriate modules for 16-bit PCMCIA devices if the kernel is modularized and the hotplug subsystem is used.


Support for 32 bit uid’s and gid’s is required if you want to use the newer version 2 quota format. Quota-tools version 3.07 and newer has this support. Use the recommended version or newer from the table above.

Intel IA32 microcode

A driver has been added to allow updating of Intel IA32 microcode, accessible as a normal (misc) character device. If you are not using udev you may need to:

mkdir /dev/cpu
mknod /dev/cpu/microcode c 10 184
chmod 0644 /dev/cpu/microcode

as root before you can use this. You’ll probably also want to get the user-space microcode_ctl utility to use with this.


udev is a userspace application for populating /dev dynamically with only entries for devices actually present. udev replaces the basic functionality of devfs, while allowing persistent device naming for devices.


Needs libfuse 2.4.0 or later. Absolute minimum is 2.3.0 but mount options direct_io and kernel_cache won’t work.


General changes

If you have advanced network configuration needs, you should probably consider using the network tools from ip-route2.

Packet Filter / NAT

The packet filtering and NAT code uses the same tools like the previous 2.4.x kernel series (iptables). It still includes backwards-compatibility modules for 2.2.x-style ipchains and 2.0.x-style ipfwadm.


The PPP driver has been restructured to support multilink and to enable it to operate over diverse media layers. If you use PPP, upgrade pppd to at least 2.4.0.

If you are not using udev, you must have the device file /dev/ppp which can be made by:

mknod /dev/ppp c 108 0

as root.


Due to changes in the length of the phone number field, isdn4k-utils needs to be recompiled or (preferably) upgraded.


In ancient (2.4 and earlier) kernels, the nfs server needed to know about any client that expected to be able to access files via NFS. This information would be given to the kernel by mountd when the client mounted the filesystem, or by exportfs at system startup. exportfs would take information about active clients from /var/lib/nfs/rmtab.

This approach is quite fragile as it depends on rmtab being correct which is not always easy, particularly when trying to implement fail-over. Even when the system is working well, rmtab suffers from getting lots of old entries that never get removed.

With modern kernels we have the option of having the kernel tell mountd when it gets a request from an unknown host, and mountd can give appropriate export information to the kernel. This removes the dependency on rmtab and means that the kernel only needs to know about currently active clients.

To enable this new functionality, you need to:

mount -t nfsd nfsd /proc/fs/nfsd

before running exportfs or mountd. It is recommended that all NFS services be protected from the internet-at-large by a firewall where that is possible.


On x86 kernels the mcelog utility is needed to process and log machine check events when CONFIG_X86_MCE is enabled. Machine check events are errors reported by the CPU. Processing them is strongly encouraged.

Kernel documentation


Please see Sphinx Install in Documentation/doc-guide/sphinx.rst for details about Sphinx requirements.

Getting updated software

Kernel documentation