Home > Articles > Operating Systems, Server > Linux/UNIX/Open Source

This chapter is from the book

This chapter is from the book

Building a Linux kernel

Because Linux is evolving so rapidly, it is much more likely that you'll be faced with the need to build a Linux kernel than you would if you were running a big-iron operating system. Kernel patches, device drivers, and new functionality are constantly becoming available. This is really something of a mixed blessing. On one hand, it's convenient to always have support for the "latest and greatest," but on the other hand it can become quite time consuming to keep up with the constant flow of new material. But after you successfully build a kernel once, you'll feel empowered and eager to do it again.

It's less likely that you'll need to build a kernel on your own if you're running a "stable" version. Linux has adopted a versioning scheme in which the second part of the version number indicates whether the kernel is stable (even numbers) or in development (odd numbers). For example, kernel version 2.4.3 would be a "stable" kernel, whereas 2.5.3 would be a "development" kernel. Now you know.

Linux kernel configuration has come a long way, but it still feels very primitive compared to the procedures used on some other systems. The process revolves around the .config file in the root of the kernel source directory (usually /usr/src/linux).4 All of the kernel configuration information is specified in this file, but its format is somewhat cryptic. Use the decoding guide in Documentation/Configure.help to find out what the various options mean.

To save folks from having to edit the .config file directly, Linux has several make targets that let you configure the kernel with different interfaces. If you are running X Windows, the prettiest configuration interface is provided by make xconfig. This command brings up a graphical configuration screen on which you can pick the devices to add to your kernel (or compile as loadable modules).

If you are not running X, you can use a curses-based5 alternative invoked with make menuconfig. Finally, there is the older style make config, which prompts you to respond to every single configuration option available without letting you later go back and change your mind.

We recommend make xconfig if you are running X and make menuconfig if you aren't. Avoid make config.

These tools are straightforward as far as the options you can turn on, but unfortunately they are painful to use if you want to maintain several versions of the kernel for multiple architectures or hardware configurations.

The various configuration interfaces described above all generate a .config file that looks something like this:

# Automatically generated make config: don't edit
# Code maturity level options

# Processor type and features
# CONFIG_M386 is not set
# CONFIG_M486 is not set
# CONFIG_M586 is not set
# CONFIG_M586TSC is not set

As you can see, the contents are rather cryptic and provide no descriptions of what the CONFIG tags mean. Sometimes you can figure out the meaning. Basically, each CONFIG line refers to a specific kernel configuration option. The value y compiles the option into the kernel; m enables it, but as a loadable module.

Some things can be configured as modules and some can't. You just have to know which is which; it's not clear from the .config file. There is also no easy mapping of the CONFIG tags to meaningful information. However, you can usually extract this information from the Config.in file located in each driver directory. The Config.in files are difficult and inconvenient to track down, so it's best to just use make xconfig or make menuconfig.

Once you have a working, running kernel, you may need to pass special configuration options to it at boot time, such as the root device it should use or an instruction to probe for multiple Ethernet cards. The boot loader (typically LILO or GRUB) passes in these options. You add static configuration options to the /etc/lilo.conf or /boot/grub/grub.conf file, depending on which boot loader you use. See page 23 for more information.

If it's not possible to edit the boot loader configuration file (perhaps you broke something and the machine can't boot), you can pass the options in by hand. For example, at a LILO boot prompt you could type

LILO: linux root=/dev/hda1 ether=0,0,eth0 ether=0,0,eth1

to tell LILO to load the kernel specified by the "linux" tag, to use the root device /dev/hda1, and to probe for two Ethernet cards.

A similar example using GRUB would look like this:

grub> kernel /vmlinuz root=/dev/hda1 ether=0,0,eth0 ether=0,0,eth1
grub> boot 

Building the Linux kernel binary

Setting up an appropriate .config file is the most important part of the Linux kernel configuration process, but you must jump through several more hoops to turn that file into a finished kernel.

Here's an outline of the entire process:

  • cd to /usr/src/linux.

  • Run make xconfig or make menuconfig.

  • Run make dep.

  • Run make clean.

  • Run make bzImage.

  • Run make modules.

  • Run make modules_install.

  • Copy /usr/src/linux/arch/i386/boot/bzImage to /boot/vmlinuz.

  • Copy /usr/src/linux/arch/i386/boot/System.map to /boot/System.map.

  • Edit /etc/lilo.conf (LILO) or /boot/grub/grub.conf (GRUB) to add a configuration line for the new kernel.

  • If you're using LILO, run /sbin/lilo to install the reconfigured boot loader.

The make clean step is not always strictly necessary, but it is generally a good idea to start with a clean build environment. In practice, many problems can be traced back to skipping this step.

InformIT Promotional Mailings & Special Offers

I would like to receive exclusive offers and hear about products from InformIT and its family of brands. I can unsubscribe at any time.


Pearson Education, Inc., 221 River Street, Hoboken, New Jersey 07030, (Pearson) presents this site to provide information about products and services that can be purchased through this site.

This privacy notice provides an overview of our commitment to privacy and describes how we collect, protect, use and share personal information collected through this site. Please note that other Pearson websites and online products and services have their own separate privacy policies.

Collection and Use of Information

To conduct business and deliver products and services, Pearson collects and uses personal information in several ways in connection with this site, including:

Questions and Inquiries

For inquiries and questions, we collect the inquiry or question, together with name, contact details (email address, phone number and mailing address) and any other additional information voluntarily submitted to us through a Contact Us form or an email. We use this information to address the inquiry and respond to the question.

Online Store

For orders and purchases placed through our online store on this site, we collect order details, name, institution name and address (if applicable), email address, phone number, shipping and billing addresses, credit/debit card information, shipping options and any instructions. We use this information to complete transactions, fulfill orders, communicate with individuals placing orders or visiting the online store, and for related purposes.


Pearson may offer opportunities to provide feedback or participate in surveys, including surveys evaluating Pearson products, services or sites. Participation is voluntary. Pearson collects information requested in the survey questions and uses the information to evaluate, support, maintain and improve products, services or sites, develop new products and services, conduct educational research and for other purposes specified in the survey.

Contests and Drawings

Occasionally, we may sponsor a contest or drawing. Participation is optional. Pearson collects name, contact information and other information specified on the entry form for the contest or drawing to conduct the contest or drawing. Pearson may collect additional personal information from the winners of a contest or drawing in order to award the prize and for tax reporting purposes, as required by law.


If you have elected to receive email newsletters or promotional mailings and special offers but want to unsubscribe, simply email information@informit.com.

Service Announcements

On rare occasions it is necessary to send out a strictly service related announcement. For instance, if our service is temporarily suspended for maintenance we might send users an email. Generally, users may not opt-out of these communications, though they can deactivate their account information. However, these communications are not promotional in nature.

Customer Service

We communicate with users on a regular basis to provide requested services and in regard to issues relating to their account we reply via email or phone in accordance with the users' wishes when a user submits their information through our Contact Us form.

Other Collection and Use of Information

Application and System Logs

Pearson automatically collects log data to help ensure the delivery, availability and security of this site. Log data may include technical information about how a user or visitor connected to this site, such as browser type, type of computer/device, operating system, internet service provider and IP address. We use this information for support purposes and to monitor the health of the site, identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents and appropriately scale computing resources.

Web Analytics

Pearson may use third party web trend analytical services, including Google Analytics, to collect visitor information, such as IP addresses, browser types, referring pages, pages visited and time spent on a particular site. While these analytical services collect and report information on an anonymous basis, they may use cookies to gather web trend information. The information gathered may enable Pearson (but not the third party web trend services) to link information with application and system log data. Pearson uses this information for system administration and to identify problems, improve service, detect unauthorized access and fraudulent activity, prevent and respond to security incidents, appropriately scale computing resources and otherwise support and deliver this site and its services.

Cookies and Related Technologies

This site uses cookies and similar technologies to personalize content, measure traffic patterns, control security, track use and access of information on this site, and provide interest-based messages and advertising. Users can manage and block the use of cookies through their browser. Disabling or blocking certain cookies may limit the functionality of this site.

Do Not Track

This site currently does not respond to Do Not Track signals.


Pearson uses appropriate physical, administrative and technical security measures to protect personal information from unauthorized access, use and disclosure.


This site is not directed to children under the age of 13.


Pearson may send or direct marketing communications to users, provided that

  • Pearson will not use personal information collected or processed as a K-12 school service provider for the purpose of directed or targeted advertising.
  • Such marketing is consistent with applicable law and Pearson's legal obligations.
  • Pearson will not knowingly direct or send marketing communications to an individual who has expressed a preference not to receive marketing.
  • Where required by applicable law, express or implied consent to marketing exists and has not been withdrawn.

Pearson may provide personal information to a third party service provider on a restricted basis to provide marketing solely on behalf of Pearson or an affiliate or customer for whom Pearson is a service provider. Marketing preferences may be changed at any time.

Correcting/Updating Personal Information

If a user's personally identifiable information changes (such as your postal address or email address), we provide a way to correct or update that user's personal data provided to us. This can be done on the Account page. If a user no longer desires our service and desires to delete his or her account, please contact us at customer-service@informit.com and we will process the deletion of a user's account.


Users can always make an informed choice as to whether they should proceed with certain services offered by InformIT. If you choose to remove yourself from our mailing list(s) simply visit the following page and uncheck any communication you no longer want to receive: www.informit.com/u.aspx.

Sale of Personal Information

Pearson does not rent or sell personal information in exchange for any payment of money.

While Pearson does not sell personal information, as defined in Nevada law, Nevada residents may email a request for no sale of their personal information to NevadaDesignatedRequest@pearson.com.

Supplemental Privacy Statement for California Residents

California residents should read our Supplemental privacy statement for California residents in conjunction with this Privacy Notice. The Supplemental privacy statement for California residents explains Pearson's commitment to comply with California law and applies to personal information of California residents collected in connection with this site and the Services.

Sharing and Disclosure

Pearson may disclose personal information, as follows:

  • As required by law.
  • With the consent of the individual (or their parent, if the individual is a minor)
  • In response to a subpoena, court order or legal process, to the extent permitted or required by law
  • To protect the security and safety of individuals, data, assets and systems, consistent with applicable law
  • In connection the sale, joint venture or other transfer of some or all of its company or assets, subject to the provisions of this Privacy Notice
  • To investigate or address actual or suspected fraud or other illegal activities
  • To exercise its legal rights, including enforcement of the Terms of Use for this site or another contract
  • To affiliated Pearson companies and other companies and organizations who perform work for Pearson and are obligated to protect the privacy of personal information consistent with this Privacy Notice
  • To a school, organization, company or government agency, where Pearson collects or processes the personal information in a school setting or on behalf of such organization, company or government agency.


This web site contains links to other sites. Please be aware that we are not responsible for the privacy practices of such other sites. We encourage our users to be aware when they leave our site and to read the privacy statements of each and every web site that collects Personal Information. This privacy statement applies solely to information collected by this web site.

Requests and Contact

Please contact us about this Privacy Notice or if you have any requests or questions relating to the privacy of your personal information.

Changes to this Privacy Notice

We may revise this Privacy Notice through an updated posting. We will identify the effective date of the revision in the posting. Often, updates are made to provide greater clarity or to comply with changes in regulatory requirements. If the updates involve material changes to the collection, protection, use or disclosure of Personal Information, Pearson will provide notice of the change through a conspicuous notice on this site or other appropriate way. Continued use of the site after the effective date of a posted revision evidences acceptance. Please contact us if you have questions or concerns about the Privacy Notice or any objection to any revisions.

Last Update: November 17, 2020