Difference between pages "Building a Kernel from Source" and "Repository Configuration"

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Setting up a proper kernel yourself - lean, mean and tailored to your hardware,  is the challenge by which a linux user can graduate to becoming a Funtoo knight ;-)
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{{Warning|This article is a work-in-progress referring to a future Portage version. It does not apply to the current Funtoo Portage version. Please do not update your configuration yet.}}
  
Even though many of us are using enterprise-ready kernels in datacenters, there is almost nobody who hasn't at least considered building a kernel for his laptop / PC.
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Starting with Portage-2.3.8, a switch to a new repository configuration framework is complete and users may want to update their configuration files. This document aims to describe the goals for the new framework and how to use it.
We are showing here how an intermediate Linux user can use an alternative to the standard beginners "genkernel" approach,  to compile a custom kernel,  in a relatively speedy and easy set up.
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== Minimum Requirements ==
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== Multiple repository layout ==
* '''Understand the command line'''
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One of the most important changes is the switch from the old ''overlay'' layout to a new cleaner ''repository'' system. The new layout is more flexible and more predictable. For example, repositories can now use resources (eclasses, for example) provided by other repositories.
* '''Know where the kernel files are located'''
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== Assumptions ==
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The old layout was based on the concept of one ''main tree'' and optionally a number of overlays. The main tree provided base system ebuilds, eclasses, profiles, while overlays mostly were able to provide their own ebuilds. The ebuild provided by overlays overrode the ebuilds in main tree to the extend of making it impossible to install the main tree version. Overlays could also provide eclasses for their own ebuilds and package.* entries that applied to all overlays and to the main tree. The Package Manager is responsible for updating the main tree, while overlays are managed externally.
You start from an installed Funtoo system on the disk, or at least, you are on stage3 in a chrooted environment from a live cd, following somehow the Funto [[Installation (Tutorial)|Installation Tutorial]].
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== Less advanced version ==
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The new layout is based on the concept of one or more configurable repositories. Each repository can either be stand-alone or depend upon other repositories. The distribution provides a repository called ''funtoo'' (a drop-in replacement for Gentoo's ''gentoo'' repository). Users can install more repositories at they will, the repositories providing their own ebuilds, eclasses and profiles as necessary and/or using them from other repositories. Users can explicitly choose the repository they want to install packages from. The Package Manager can update all repositories.
=== Emerging the kernel sources ===
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To begin, we have to figure out which kernel sources we will use. If you are unsure about which sources are available and what their benefits and drawbacks are, check out the [[Funtoo_Linux_Kernels| Kernels]] page.
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After you have made a decsion as to which kernel you want to install, emerge it:
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== Portage configuration ==
<console>
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=== New repository layout ===
###i## emerge vanilla-sources
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The repository configuration should be stored in <code>/etc/portage/repos.conf</code>. It can be either a single file or a directory containing one or more ''.conf'' files.
</console>
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Portage will now go about installing the sources to ''/usr/src''. It will also symlink the kernel-version directory to a directory called ''linux''.
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=== Configuring the kernel ===
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The default configuration is installed as <code>/usr/share/portage/config/repos.conf</code>. This file is internal configuration file installed with portage ebuild and should '''not''' be modified. Instead, the configuration in <code>/etc/portage/repos.conf</code> can override the defaults specified there.
Now that the kernel sources are on your system, you should configure them. To do this, change your directory to ''/usr/src/linux''
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<console>
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###i## cd /usr/src/linux
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</console>
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As we are now in the kernel sources directory, we can run a script that allows us to modify them. Run:
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<console>
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###i## make menuconfig
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</console>
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While you edit the sources, keep the following in mind:
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* To build something into your kernel, press y when you have it selected.
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* To exclude something from your kernel, press n when you have it selected.
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* To build something as a module, press m.  
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Things that you may need to include in your kernel:
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The configuration uses format similar to Windows .ini files. Each section heading (repository name in square brackets) signifies a single repository, followed by one or more key-value option pairs. For example, the following file copies default configuration for Funtoo repository:
* Wireless/LAN drivers
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* Support for your graphics card
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* Support for your audio card
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* Support for USB devices
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{{fancynote| Many pages on the wiki will tell you the kernel requirements for the application that they are about. Keep your eyes open for the blue background, white text sections of pages. Like on this one: [[uvesafb| uvesafb]]}}
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=== Building and installing the kernel sources ===
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{{file|name=/etc/portage/repos.conf/funtoo.conf|desc=Example configuration override for Funtoo repository|body=
After you finish configuring your kernel sources, you will need to build them. To build your sources, run the following:
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[funtoo]
<console>
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# moved to non-default location!
###i## make
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location = /var/db/repos/funtoo
</console>
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sync-type = git
{{fancytip| You can add -j<number of processing cores + 1> after make to build the kernel more quickly.}}
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sync-uri = git://github.com/funtoo/ports-2015.git
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auto-sync = yes
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}}
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Location variable is now what used to be a PORTDIR, when using old-fashioned <code>/etc/portage/make.conf</code>.  <code>/var/db/repos/funtoo</code> is a dummy location example. Default location in Funtoo is  set to <code>/usr/portage</code>. Users are free to choose a location of their suits. sync-type is a CVS tree used for portage tree, git is a default in Funtoo. sync-uri is what used to be a SYNC variable, when using old-fashioned configuration through <code>/etc/portage/make.conf</code>
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The most useful repository configuration options are listed below:
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;location: ''Obligatory.'' Specifies the directory where repository is/will be stored. If Portage knows how to sync the repository and the location does not exist, it will be created on next ''emerge --sync''. Otherwise, the directory must exist.
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;priority: Specifies the priority used for ordering ebuilds from different repositories. If two repositories provide an ebuild with matching versions, the repository with higher priority will be used.
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;auto-sync: Specifies whether ''emerge --sync'' should update the repository. Defaults to ''yes'' if ''sync-type'' is specified, ''no'' otherwise.
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;sync-depth: Specifies ''--depth'' for git clone. Used only on initial sync. Defaults to 1. Can be set to 0 to force full clone (not pass ''--depth'' at all).
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;sync-type: Specifies syncing/update method. Can be one of: ''cvs'', ''git'', ''rsync'', ''svn''.
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;sync-umask: Specifies the umask used when updating/syncing the repository.
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;sync-uri: Specifies remote URI from which the repository will be cloned/synced. Can use any syntax valid for a particular syncing method.
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;sync-user: Specifies the user[:group] used to update/sync the repository. If ''FEATURES=usersync'' is used, defaults to the credentials of directory owner.
  
When the kernel and its modules finish building, install them:
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[[Category:Portage]]
<console>
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###i## make install modules_install
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</console>
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Now that you have installed your kernel and modules, it is a good idea to install an initramfs. If your system has a separate ''/usr'' partition, is encrypted, or uses some other non-standard configuration, it will probably not boot without an initramfs. See [[Building_a_Kernel_from_Source#Initramfs| Initramfs]].
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== Advanced version ==
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=== Getting ready to start ===
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{{fancynote| In this case we are building a kernel that is booting root in LVM over encrypted LUKS container.
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If you don't have this setup, don't worry, you just don't need all the modules, but everything else is similar.}}
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First, there is the decision which linux kernel sources we need.
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There are plenty of them in the repositories around, often it is not easy to distinguish between them.
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I would always trust my distribution of choice and take what is has to offer - and funtoo has a lot to offer!
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I really do recommend (especially if it is your first time) to build a debian-sourced genkernel like described in chapter 5 "Using Debian-Sources with Genkernel" in the [[Funtoo_Linux_Kernels| Funtoo Kernels Tutorial]].
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From there you should have a running system booting nicely from your own build (just little bit bloated) kernel. This is more than you can expect from any other ready to go distribution.
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{{fancynote| We are using RedHat's dracut in order to build a nice initramfs (containing all the necessary tools and extra drivers our kernel might need to start the system). Although dracut is the way to go, more sophisticated and not as buggy as gentoo's genkernel approach, more and more funtoo geeks start using slashbeast's better-initramfs, which we will cover at the end of this howto! So after having set up a genkernel from debian or gentoo sources we are going to build a kernel with either (or both) dracut or/and better-initramfs. So gentoo sources with genkernel is always my backup if anything is not working correctly on my system. For the slightly more geeky approach with my own initram I am using pf-sources, ck-sources or any other more or less heavily patched sources.}}
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Let's go!
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=== Kernel Sources ===
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The source you use on your system is up to you. For a laptop or desktop system, the following are recommended:
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* '''{{Package|sys-kernel/pf-sources}}'''
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* '''{{Package|sys-kernel/ck-sources}}'''
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* '''{{Package|sys-kernel/gentoo-sources}}'''
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* '''{{Package|sys-kernel/git-sources}}'''
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* '''{{Package|sys-kernel/sysrescue-std-sources}}'''
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* '''{{Package|sys-kernel/debian-sources}}'''
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{{fancynote| If you are unsure of which sources you would like to use, emerge <code>gentoo-sources</code>. That's always a safe bet for a general system. For more information on available kernels, check out: [[Funtoo Linux Kernels]]}}
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=== Prerequisites ===
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Regardless of the tools you already have installed, it is recommended to follow the steps below, even if you find them to be redundant.
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First, we edit our <code>/etc/portage/make.conf</code>:
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<pre>
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#These compiler flags are just tweaking (optimazation) and NOT necessary:
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CFLAGS="-O2 -pipe -march=native -ftracer -fforce-addr"
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CXXFLAGS="${CFLAGS} -fpermissive -fomit-frame-pointer"
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KDIR=/usr/src/linux
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KERNEL="symlink build"
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USE="$KERNEL ....here are your use flags...."
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## These modules are available:
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## DRACUT_MODULES="dracut_modules_biosdevname dracut_modules_btrfs dracut_modules_caps dracut_modules_crypt dracut_modules_crypt-gpg dracut_modules_dmraid dracut_modules_dmsquash-live dracut_modules_gensplash dracut_modules_iscsi dracut_modules_livenet dracut_modules_lvm dracut_modules_mdraid dracut_modules_multipath dracut_modules_nbd dracut_modules_nfs dracut_modules_plymouth dracut_modules_ssh-client dracut_modules_syslog"
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## We will use these modules for LVM / LUKS:
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DRACUT_MODULES="crypt lvm plymouth biosdevname dmraid crypt-gpg dmsquash-live ssh-client syslog"
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</pre>
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Next, we set the package keywords by adding the following to <code>/etc/portage/package.use</code>:
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<pre>
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sys-kernel/dracut dm net device-mapper crypt lvm
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</pre>
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{{fancynote| If you don't have lvm over encrypted LUKS you just add the "net" keyword here, or "selinux".}}
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Next, we build our packages:
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<console>
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###i## emerge -av app-portage/gentoolkit sys-kernel/pf-sources sys-kernel/dracut sys-boot/plymouth sys-boot/plymouth-openrc-plugin
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</console>
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=== Preparing the kernel ===
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We go now to the sources directory and enter the following commands to update the kernel's  .config  file:
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<console>
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###i## cd /usr/src/linux/
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###i## make clean
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  CLEAN  .
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  CLEAN  arch/x86/kernel/acpi/realmode
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  CLEAN  arch/x86/kernel/cpu
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  CLEAN  arch/x86/kernel
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  CLEAN  arch/x86/vdso
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  CLEAN  arch/x86/lib
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  CLEAN  drivers/gpu/drm/radeon
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  CLEAN  drivers/net/wan
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  CLEAN  drivers/scsi/aic7xxx
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  CLEAN  drivers/tty/vt
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  CLEAN  drivers/video/logo
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  CLEAN  firmware
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  CLEAN  kernel
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  CLEAN  lib/raid6
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  CLEAN  lib
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  CLEAN  security/apparmor
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  CLEAN  security/selinux
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  CLEAN  usr
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  CLEAN  arch/x86/boot/compressed
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  CLEAN  arch/x86/boot
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  CLEAN  .tmp_versions
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  CLEAN  vmlinux System.map .tmp_kallsyms2.S .tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms1.S .tmp_vmlinux1 .tmp_vmlinux2 .tmp_System.map
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###i## zcat /proc/config.gz > /usr/src/linux/.config
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</console>
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Next, we run <tt>make localmodconfig</tt>. You will get some questions which you can answer mostly with either M (compiled as a module) or Y (compiled directly into the kernel). If you are not sure what to choose, press enter, and the default option will be selected.
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<console>
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###i## make localmodconfig
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Enable different security models (SECURITY) [Y/n/?] y
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Enable the securityfs filesystem (SECURITYFS) [Y/?] y
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Socket and Networking Security Hooks (SECURITY_NETWORK) [Y/?] y
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Security hooks for pathname based access control (SECURITY_PATH) [Y/?] y
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Low address space for LSM to protect from user allocation (LSM_MMAP_MIN_ADDR) [65536] 65536
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NSA SELinux Support (SECURITY_SELINUX) [Y/n/?] y
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  NSA SELinux boot parameter (SECURITY_SELINUX_BOOTPARAM) [N/y/?] n
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  NSA SELinux runtime disable (SECURITY_SELINUX_DISABLE) [N/y/?] n
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  NSA SELinux Development Support (SECURITY_SELINUX_DEVELOP) [Y/n/?] y
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  NSA SELinux AVC Statistics (SECURITY_SELINUX_AVC_STATS) [Y/n/?] y
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  NSA SELinux checkreqprot default value (SECURITY_SELINUX_CHECKREQPROT_VALUE) [1] 1
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  NSA SELinux maximum supported policy format version (SECURITY_SELINUX_POLICYDB_VERSION_MAX) [Y/n/?] y
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    NSA SELinux maximum supported policy format version value (SECURITY_SELINUX_POLICYDB_VERSION_MAX_VALUE) [19] 19
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TOMOYO Linux Support (SECURITY_TOMOYO) [Y/n/?] y
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  Default maximal count for learning mode (SECURITY_TOMOYO_MAX_ACCEPT_ENTRY) [2048] 2048
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  Default maximal count for audit log (SECURITY_TOMOYO_MAX_AUDIT_LOG) [1024] 1024
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  Activate without calling userspace policy loader. (SECURITY_TOMOYO_OMIT_USERSPACE_LOADER) [Y/n/?] y
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AppArmor support (SECURITY_APPARMOR) [Y/n/?] y
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  AppArmor boot parameter default value (SECURITY_APPARMOR_BOOTPARAM_VALUE) [1] 1
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Integrity Measurement Architecture(IMA) (IMA) [Y/n/?] y
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EVM support (EVM) [N/y/?] (NEW)
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Default security module
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  1. SELinux (DEFAULT_SECURITY_SELINUX)
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  2. TOMOYO (DEFAULT_SECURITY_TOMOYO)
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  3. AppArmor (DEFAULT_SECURITY_APPARMOR)
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> 4. Unix Discretionary Access Controls (DEFAULT_SECURITY_DAC)
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choice[1-4?]: 4
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warning: (ACPI_HOTPLUG_CPU) selects ACPI_CONTAINER which has unmet direct dependencies (ACPI && EXPERIMENTAL)
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warning: (MEDIA_TUNER) selects MEDIA_TUNER_TEA5761 which has unmet direct dependencies (MEDIA_SUPPORT && VIDEO_MEDIA && I2C && EXPERIMENTAL)
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#
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# configuration written to .config
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#
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warning: (GFS2_FS) selects DLM which has unmet direct dependencies (EXPERIMENTAL && INET && SYSFS && CONFIGFS_FS && (IPV6 || IPV6=n))
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warning: (IMA) selects TCG_TPM which has unmet direct dependencies (HAS_IOMEM && EXPERIMENTAL)
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warning: (MEDIA_TUNER) selects MEDIA_TUNER_TEA5761 which has unmet direct dependencies (MEDIA_SUPPORT && VIDEO_MEDIA && I2C && EXPERIMENTAL)
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warning: (ACPI_HOTPLUG_CPU) selects ACPI_CONTAINER which has unmet direct dependencies (ACPI && EXPERIMENTAL)
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</console>
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Now comes the most adventurous part!
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=== Building the Kernel ===
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<console>
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###i## make -j8  bzImage
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###i## make -j8 modules
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###i## make modules_install
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###i## make install
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</console>
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== Initramfs ==
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{{fancywarning| Make sure that you have built and installed your kernel sources / modules before building an initramfs.}}
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To get your initramfs up and running, check out the [http://www.funtoo.org/Initramfs Initramfs] page. After following all the directions on the page to get your initramfs set up, continue following the ones here.
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Update the <tt>grub.cfg</tt> with boot update, then reboot and see how it works!
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<console>
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###i## boot-update -v
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###i## reboot
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</console>
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[[Category:HOWTO]]
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[[Category:Featured]]
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[[Category:Kernel]]
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Revision as of 13:52, February 14, 2015

Warning

This article is a work-in-progress referring to a future Portage version. It does not apply to the current Funtoo Portage version. Please do not update your configuration yet.

Starting with Portage-2.3.8, a switch to a new repository configuration framework is complete and users may want to update their configuration files. This document aims to describe the goals for the new framework and how to use it.

Multiple repository layout

One of the most important changes is the switch from the old overlay layout to a new cleaner repository system. The new layout is more flexible and more predictable. For example, repositories can now use resources (eclasses, for example) provided by other repositories.

The old layout was based on the concept of one main tree and optionally a number of overlays. The main tree provided base system ebuilds, eclasses, profiles, while overlays mostly were able to provide their own ebuilds. The ebuild provided by overlays overrode the ebuilds in main tree to the extend of making it impossible to install the main tree version. Overlays could also provide eclasses for their own ebuilds and package.* entries that applied to all overlays and to the main tree. The Package Manager is responsible for updating the main tree, while overlays are managed externally.

The new layout is based on the concept of one or more configurable repositories. Each repository can either be stand-alone or depend upon other repositories. The distribution provides a repository called funtoo (a drop-in replacement for Gentoo's gentoo repository). Users can install more repositories at they will, the repositories providing their own ebuilds, eclasses and profiles as necessary and/or using them from other repositories. Users can explicitly choose the repository they want to install packages from. The Package Manager can update all repositories.

Portage configuration

New repository layout

The repository configuration should be stored in /etc/portage/repos.conf. It can be either a single file or a directory containing one or more .conf files.

The default configuration is installed as /usr/share/portage/config/repos.conf. This file is internal configuration file installed with portage ebuild and should not be modified. Instead, the configuration in /etc/portage/repos.conf can override the defaults specified there.

The configuration uses format similar to Windows .ini files. Each section heading (repository name in square brackets) signifies a single repository, followed by one or more key-value option pairs. For example, the following file copies default configuration for Funtoo repository:

/etc/portage/repos.conf/funtoo.conf - Example configuration override for Funtoo repository
[funtoo]
# moved to non-default location!
location = /var/db/repos/funtoo
sync-type = git
sync-uri = git://github.com/funtoo/ports-2015.git
auto-sync = yes

Location variable is now what used to be a PORTDIR, when using old-fashioned /etc/portage/make.conf. /var/db/repos/funtoo is a dummy location example. Default location in Funtoo is set to /usr/portage. Users are free to choose a location of their suits. sync-type is a CVS tree used for portage tree, git is a default in Funtoo. sync-uri is what used to be a SYNC variable, when using old-fashioned configuration through /etc/portage/make.conf The most useful repository configuration options are listed below:

location
Obligatory. Specifies the directory where repository is/will be stored. If Portage knows how to sync the repository and the location does not exist, it will be created on next emerge --sync. Otherwise, the directory must exist.
priority
Specifies the priority used for ordering ebuilds from different repositories. If two repositories provide an ebuild with matching versions, the repository with higher priority will be used.
auto-sync
Specifies whether emerge --sync should update the repository. Defaults to yes if sync-type is specified, no otherwise.
sync-depth
Specifies --depth for git clone. Used only on initial sync. Defaults to 1. Can be set to 0 to force full clone (not pass --depth at all).
sync-type
Specifies syncing/update method. Can be one of: cvs, git, rsync, svn.
sync-umask
Specifies the umask used when updating/syncing the repository.
sync-uri
Specifies remote URI from which the repository will be cloned/synced. Can use any syntax valid for a particular syncing method.
sync-user
Specifies the user[:group] used to update/sync the repository. If FEATURES=usersync is used, defaults to the credentials of directory owner.