Difference between pages "Building a Kernel from Source" and "Installing a Cron Daemon"

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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 ;-)
+
== Introduction ==
 
+
Cron daemons allow you to configure certain tasks to be run at specific times. Installing a cron daemon is a good idea because some packages may assume that you have a cron daemon installed and create jobs to update their databases with a cron daemon. There are several different loggers available to Funtoo users:
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.
+
* '''Fcron'''  
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.
+
* '''Cronie'''
 
+
* '''Vixie-Cron'''
== Minimum Requirements ==
+
* '''Understand the command line'''
+
* '''Know where the kernel files are located'''
+
 
+
== Assumptions ==
+
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]].
+
 
+
In this case we are building a kernel that is booting root in LVM over encrypted LUKS container.
+
If you don't have this setup, don't worry, you just don't need all the modules, but everything else is similar.
+
 
+
 
+
== Getting ready to start ==
+
 
+
First there is the decision which linux kernel sources we need.
+
There are plenty of them in the repositories around, often it is not easy to distinguish between them.
+
 
+
I would always trust my distribution of choice and take what is has to offer - and funtoo has a lot to offer!
+
 
+
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]].
+
 
+
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.
+
 
+
{{Note}} 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.
+
 
+
Let's go!
+
 
+
== Kernel Sources ==
+
We are going to use the kernel sources from the funtoo git repository.
+
 
+
The source you use on your system is up to you and your needs.
+
For a laptop or desktop system, we recommend the following:
+
 
+
* '''{{Package|sys-kernel/pf-sources}}'''
+
* '''{{Package|sys-kernel/ck-sources}}'''
+
* '''{{Package|sys-kernel/gentoo-sources}}'''
+
* '''{{Package|sys-kernel/git-sources}}'''
+
* '''{{Package|sys-kernel/sysrescue-std-sources}}'''
+
* '''{{Package|sys-kernel/debian-sources}}'''
+
 
+
Please, have a look in the ebuild description, look onto their homepage and take the one that suits you best!
+
If you are unsure for now, use sys-kernel/gentoo-sources. That's always a safe bet for a general system.
+
 
+
It is not a problem to have various kernels installed parallel, so go on with any one of them.
+
 
+
I am going to use the sys-kernel/pf-sources now, as I already had the gentoo-sources installed.
+
 
+
== Prerequisites ==
+
 
+
I don't know which tools you have already installed, so some information here might be redundant.
+
It doesn't harm to just copy and paste and do some steps again.
+
 
+
First, we look into our <code>/etc/make.conf</code>:
+
  
 +
== Installation ==
 +
To install the cron daemon, run the following command:
 
<console>
 
<console>
###i## nano /etc/make.conf
+
# ##i## emerge --ask fcron
#These compiler flags are just tweaking (optimazation) and NOT necessary:
+
CFLAGS="-O2 -pipe -march=native -ftracer -fforce-addr"
+
CXXFLAGS="${CFLAGS} -fpermissive -fomit-frame-pointer"
+
KDIR=/usr/src/linux
+
KERNEL="symlink build"
+
USE="$KERNEL ....here are your use flags...."
+
## These modules are available:
+
## 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"
+
## We will use these modules for LVM / LUKS:
+
DRACUT_MODULES="crypt lvm plymouth biosdevname dmraid crypt-gpg dmsquash-live ssh-client syslog"
+
</console>
+
  
Next, we set the package keywords:
+
These are the packages that would be merged, in order:
<console>
+
###i## nano /etc/portage/package.use/dracut
+
sys-kernel/dracut dm net device-mapper crypt lvm
+
</console>
+
  
{{Note}} If you don't have lvm over encrypted LUKS you probably just add the "net" keyword here, or "selinux".
+
Calculating dependencies... done!
 +
[ebuild  N    ] sys-process/cronbase-0.3.2-r1
 +
[ebuild  N    ] sys-process/fcron-3.1.2-r2  USE="mta pam readline system-crontab -debug (-selinux)" LINGUAS="-fr"  
  
 
+
##b## Would you like to merge these packages? [Yes/No]##i## yes
After that we are going to build our packages:
+
<console>
+
###i## emerge -av app-portage/gentoolkit sys-kernel/pf-sources sys-kernel/dracut sys-boot/plymouth sys-boot/plymouth-openrc-plugin
+
 
</console>
 
</console>
  
Finished? Well, then let's go on and
+
Now enable the cron init script so that is starts when your system boots, and enable the cron daemon:
  
== Preparing the kernel ==
 
 
We go now to the sources directory and enter the following commands to update the kernel's  .config  file:
 
 
<console>
 
<console>
###i## cd /usr/src/linux/
+
# ##i##rc-update add fcron default
###i## make clean
+
* service fcron added to runlevel default
  CLEAN  .
+
# ##i##rc
  CLEAN  arch/x86/kernel/acpi/realmode
+
* Caching service dependencies ...              [ ok ]
  CLEAN  arch/x86/kernel/cpu
+
* Starting fcron ...                           [ ok ]
  CLEAN  arch/x86/kernel
+
  CLEAN  arch/x86/vdso
+
  CLEAN  arch/x86/lib
+
  CLEAN  drivers/gpu/drm/radeon
+
  CLEAN  drivers/net/wan
+
  CLEAN  drivers/scsi/aic7xxx
+
  CLEAN  drivers/tty/vt
+
  CLEAN  drivers/video/logo
+
  CLEAN  firmware
+
  CLEAN  kernel
+
  CLEAN  lib/raid6
+
  CLEAN  lib
+
  CLEAN  security/apparmor
+
  CLEAN  security/selinux
+
  CLEAN  usr
+
  CLEAN  arch/x86/boot/compressed
+
  CLEAN  arch/x86/boot
+
  CLEAN  .tmp_versions
+
  CLEAN  vmlinux System.map .tmp_kallsyms2.S .tmp_kallsyms1.o .tmp_kallsyms2.o .tmp_kallsyms1.S .tmp_vmlinux1 .tmp_vmlinux2 .tmp_System.map
+
###i## zcat /proc/config.gz > /usr/src/linux/.config
+
</console>
+
<br>
+
<console>
+
###i## make localmodconfig
+
 
</console>
 
</console>
  
You will get some questions which you can answer mostly with either M (compiled as a module) or Y (compiled directly into the kernel).
+
=== System Cron Jobs ===
<pre>
+
Enable different security models (SECURITY) [Y/n/?] y
+
Enable the securityfs filesystem (SECURITYFS) [Y/?] y
+
Socket and Networking Security Hooks (SECURITY_NETWORK) [Y/?] y
+
Security hooks for pathname based access control (SECURITY_PATH) [Y/?] y
+
Low address space for LSM to protect from user allocation (LSM_MMAP_MIN_ADDR) [65536] 65536
+
NSA SELinux Support (SECURITY_SELINUX) [Y/n/?] y
+
  NSA SELinux boot parameter (SECURITY_SELINUX_BOOTPARAM) [N/y/?] n
+
  NSA SELinux runtime disable (SECURITY_SELINUX_DISABLE) [N/y/?] n
+
  NSA SELinux Development Support (SECURITY_SELINUX_DEVELOP) [Y/n/?] y
+
  NSA SELinux AVC Statistics (SECURITY_SELINUX_AVC_STATS) [Y/n/?] y
+
  NSA SELinux checkreqprot default value (SECURITY_SELINUX_CHECKREQPROT_VALUE) [1] 1
+
  NSA SELinux maximum supported policy format version (SECURITY_SELINUX_POLICYDB_VERSION_MAX) [Y/n/?] y
+
    NSA SELinux maximum supported policy format version value (SECURITY_SELINUX_POLICYDB_VERSION_MAX_VALUE) [19] 19
+
TOMOYO Linux Support (SECURITY_TOMOYO) [Y/n/?] y
+
  Default maximal count for learning mode (SECURITY_TOMOYO_MAX_ACCEPT_ENTRY) [2048] 2048
+
  Default maximal count for audit log (SECURITY_TOMOYO_MAX_AUDIT_LOG) [1024] 1024
+
  Activate without calling userspace policy loader. (SECURITY_TOMOYO_OMIT_USERSPACE_LOADER) [Y/n/?] y
+
AppArmor support (SECURITY_APPARMOR) [Y/n/?] y
+
  AppArmor boot parameter default value (SECURITY_APPARMOR_BOOTPARAM_VALUE) [1] 1
+
Integrity Measurement Architecture(IMA) (IMA) [Y/n/?] y
+
EVM support (EVM) [N/y/?] (NEW)
+
Default security module
+
  1. SELinux (DEFAULT_SECURITY_SELINUX)
+
  2. TOMOYO (DEFAULT_SECURITY_TOMOYO)
+
  3. AppArmor (DEFAULT_SECURITY_APPARMOR)
+
> 4. Unix Discretionary Access Controls (DEFAULT_SECURITY_DAC)
+
choice[1-4?]: 4
+
warning: (ACPI_HOTPLUG_CPU) selects ACPI_CONTAINER which has unmet direct dependencies (ACPI && EXPERIMENTAL)
+
warning: (MEDIA_TUNER) selects MEDIA_TUNER_TEA5761 which has unmet direct dependencies (MEDIA_SUPPORT && VIDEO_MEDIA && I2C && EXPERIMENTAL)
+
#
+
# configuration written to .config
+
#
+
warning: (GFS2_FS) selects DLM which has unmet direct dependencies (EXPERIMENTAL && INET && SYSFS && CONFIGFS_FS && (IPV6 || IPV6=n))
+
warning: (IMA) selects TCG_TPM which has unmet direct dependencies (HAS_IOMEM && EXPERIMENTAL)
+
warning: (MEDIA_TUNER) selects MEDIA_TUNER_TEA5761 which has unmet direct dependencies (MEDIA_SUPPORT && VIDEO_MEDIA && I2C && EXPERIMENTAL)
+
warning: (ACPI_HOTPLUG_CPU) selects ACPI_CONTAINER which has unmet direct dependencies (ACPI && EXPERIMENTAL)
+
root@[~src/linux] #
+
  
</pre>
+
After the cron daemon has been emerged, you may see a message to run <tt>emerge --config</tt> to configure your cron daemon to process system cron jobs. System cron jobs are scripts that are installed by various packages into the following directories:
  
Now comes the most adventurous part!
+
* <tt>/etc/cron.hourly</tt>
 +
* <tt>/etc/cron.daily</tt>
 +
* <tt>/etc/cron.weekly</tt>
 +
* <tt>/etc/cron.monthly</tt>
  
== Building the Kernel ==
+
For example, you should find a <tt>/etc/cron.daily/man-db</tt> script that is installed by the <tt>man-db</tt> ebuild. This system cron job updates the man cache every day.
<console>
+
###i## make -j8  bzImage
+
###i## make -j8 modules
+
###i## make modules_install
+
###i## make install
+
</console>
+
  
 +
You may choose to enable your cron daemon so that it runs system cron jobs, or choose not to. Enabling a cron daemon to run system cron jobs will result in a bit more activity on your system, but should ensure that the system runs more optimally most of the time (caching of man pages, etc.)
  
=== Initramfs, or not? ===
+
If you would like to have your system run system cron jobs, use <tt>emerge --config</tt> as specified in the emerge output:
  
The reason to build a kernel with an initramfs is mostly for interoperability (e.g. live-cd's) and special features like an included busybox, ssh, etc.  But mostly, and that's why we are doing this here now, to have a proper kernel up and running quick'n dirty in a reasonable time without fighting hours and days until a more or less exotic hardware is perfectly run by the kernel.
 
After having a proper basic kernel running with the help of an initramfs, I really recommend you to go a step further and build a true kernel with all features includes without an initramfs. But this could be pain in the ass and very time consuming - so we do it the funtoo way here - at least in the second example when we stick to better-initramfs instead of Red-Hat's ''dracut''.
 
 
== Option one: Initrd with dracut ==
 
 
To build the initrd, we just execute:
 
 
<console>
 
<console>
# ##i##dracut -f --fstab --xz /boot/initramfs-3.2.6-pf.img  3.2.6-pf
+
# ##i##emerge --config sys-process/fcron
</console>
+
Configuring pkg... * This is going to set up fcron to execute check_system_crontabs. * In this configuration, you're no longer free to edit the systab * at your leisure, at it'll be rewritten the moment the crontabs * are modified.Rebuilding fcron systab.2013-10-19 21:20:38 INFO installing file /tmp/fcrontab.84pova for user systabModifications will be taken into account right now.</console>
 
+
Generally, this really should be enough!
+
If you experience booting problems like missing modules / drivers then just boot from the genkernel section and fix the initrd building. You can look into the man page to tweak the command a bit (e.g. --add-drivers "xz dm_crypt" etc...).
+
 
+
Ok let's go on and finish the taks, we are going to tell now grub how to boot off correctly!
+
 
+
<console>
+
###i## nano /etc/boot.conf
+
 
+
boot {
+
        generate grub
+
        default "Funtoo Linux dracut"
+
        timeout 3
+
}
+
 
+
"Funtoo Linux genkernel" {
+
        kernel kernel-genkernel[-v]
+
        initrd initramfs-genkernel[-v]
+
        params = quiet rootfstype=ext4
+
        params += luks enc_root=/dev/sda3
+
        params += lvm root=/dev/mapper/vg-root
+
}
+
 
+
"Funtoo Linux dracut" {
+
        kernel vmlinuz[-v]
+
## this is the better-initramfs generated initrd
+
        initrd initramfs[-v].img
+
        params  = quiet rootfstype=ext4
+
        params += luks enc_root=/dev/sda3
+
        params += lvm root=/dev/mapper/vg-root
+
}
+
</console>
+
 
+
That's it almost!
+
 
+
Now write to the <code>grub.cfg</code> with the new handy boot-update script from funtoo:
+
<console>
+
###i## boot-update -v
+
 
+
boot-update 1.5.2 / Copyright 2009-2011 Funtoo Technologies
+
 
+
[use option "-l" for license info, "-h" for help]
+
 
+
* Generating config for grub...
+
 
+
DEFAULT > Funtoo Linux - vmlinuz-3.2.6-pf
+
          Funtoo Linux genkernel - kernel-genkernel-x86_64-3.2.6-pf
+
 
+
* Completed successfully.
+
</console>
+
 
+
Okay,... here you go..! :)
+
 
+
Reboot and see how it works!
+
 
+
= Option two: using better-initramfs =
+
 
+
Piotr's better-initramfs is another approach that is tiny, nice and shiny and seems to become more and more a favourite among funtoo'ers. The biggest plus is that, once built it is kernel version independant.
+
 
+
For using this you just do the following steps:
+
<pre>
+
1. download sources
+
2. build kernel with "make bzImage"
+
3. download better-initramfs
+
4. run better-initramfs
+
5. adjust /etc/boot.conf
+
</pre>
+
 
+
Here is how in detail:
+
 
+
Assuming you did install already a genkernel backup or at least you have a working bzImage + modules installed, we rush forward to step 3:
+
 
+
=== Downloading Better-initramfs ===
+
 
+
<console>
+
###i## cd /usr/src/;
+
###i## git clone https://github.com/slashbeast/better-initramfs.git
+
###i## /src # cd better-initramfs
+
###i## better-initramfs git:(master) ls
+
AUTHORS    LICENSE  README.rst  bootstrap  output  sourceroot
+
ChangeLog  Makefile  TODO        examples  scripts
+
</console>
+
 
+
=== Build Better-Initramfs ===
+
<console>
+
###i## better-initramfs git:(master) sudo bootstrap/bootstrap-all
+
###i## sudo make prepare
+
###i## sudo make image
+
###i## sudo mv output/initramfs.cpio.gz /boot
+
</console>
+
 
+
=== adjust grub ===
+
 
+
Taking the above setup we edit the /etc/boot.conf
+
as I installed genkernel first, and dracut after - you see this setup:
+
 
+
<pre>
+
boot {
+
        generate grub
+
        default "Funtoo Linux"
+
        timeout 3
+
}
+
 
+
# Rootfs over lvm over luks
+
# /dev/sda3 - encrypted lvm's pv
+
# /dev/mapper/vg-root - rootfs's lv
+
 
+
"Funtoo Linux" {
+
        kernel bzImage[-v]
+
## this is the better-initramfs generated initrd
+
        initrd initramfs.cpio.gz
+
        params  = quiet rootfstype=ext4
+
        params += luks enc_root=/dev/sda3
+
        params += lvm root=/dev/mapper/vg-root
+
}
+
 
+
"Funtoo Linux dracut" {
+
        kernel vmlinuz[-v]
+
## this is the dracut generated initrd
+
        initrd initramfs[-v].img
+
        params  = quiet rootfstype=ext4
+
        params += luks enc_root=/dev/sda3
+
        params += lvm root=/dev/mapper/vg-root
+
}
+
 
+
 
+
"Funtoo Linux genkernel" {
+
        kernel kernel-genkernel[-v]
+
        initrd initramfs-genkernel[-v]
+
        params = quiet rootfstype=ext4
+
        params += luks enc_root=/dev/sda3
+
        params += lvm root=/dev/mapper/vg-root
+
}
+
</pre>
+
Okay,... here you go..! :)
+
 
+
update the grub.cfg, then reboot and see how it works!
+
 
+
<console>
+
root@[~src/linux-3.2.6-pf] # boot-update -v   
+
 
+
boot-update 1.5.2 / Copyright 2009-2011 Funtoo Technologies
+
 
+
[use option "-l" for license info, "-h" for help]
+
 
+
* Generating config for grub...
+
 
+
DEFAULT > Funtoo Linux better-initramfs - vmlinuz-3.2.6-pf
+
          Funtoo Linux dracut - vmlinuz-3.2.6-pf
+
          Funtoo Linux genkernel - kernel-genkernel-x86_64-3.2.6-ck
+
 
+
* Completed successfully.
+
 
+
root@[~src/linux-3.2.6-pf] #
+
 
+
root@[~src/linux-3.2.6-pf] # reboot
+
 
+
System going down for reboot!
+
 
+
</console>
+
  
 +
Your cron daemon is now configured to automatically run system cron jobs.
  
[[Category:HOWTO]]
+
[[Category:System]]
[[Category:Featured]]
+
[[Category:Kernel]]
+

Revision as of 21:27, 19 October 2013

Introduction

Cron daemons allow you to configure certain tasks to be run at specific times. Installing a cron daemon is a good idea because some packages may assume that you have a cron daemon installed and create jobs to update their databases with a cron daemon. There are several different loggers available to Funtoo users:

  • Fcron
  • Cronie
  • Vixie-Cron

Installation

To install the cron daemon, run the following command:

#  emerge --ask fcron

These are the packages that would be merged, in order:

Calculating dependencies... done!
[ebuild  N     ] sys-process/cronbase-0.3.2-r1
[ebuild  N     ] sys-process/fcron-3.1.2-r2  USE="mta pam readline system-crontab -debug (-selinux)" LINGUAS="-fr" 

 Would you like to merge these packages? [Yes/No] yes

Now enable the cron init script so that is starts when your system boots, and enable the cron daemon:

# rc-update add fcron default
* service fcron added to runlevel default
# rc
 * Caching service dependencies ...              [ ok ]
 * Starting fcron ...                            [ ok ]

System Cron Jobs

After the cron daemon has been emerged, you may see a message to run emerge --config to configure your cron daemon to process system cron jobs. System cron jobs are scripts that are installed by various packages into the following directories:

  • /etc/cron.hourly
  • /etc/cron.daily
  • /etc/cron.weekly
  • /etc/cron.monthly

For example, you should find a /etc/cron.daily/man-db script that is installed by the man-db ebuild. This system cron job updates the man cache every day.

You may choose to enable your cron daemon so that it runs system cron jobs, or choose not to. Enabling a cron daemon to run system cron jobs will result in a bit more activity on your system, but should ensure that the system runs more optimally most of the time (caching of man pages, etc.)

If you would like to have your system run system cron jobs, use emerge --config as specified in the emerge output:

# emerge --config sys-process/fcron
Configuring pkg... * This is going to set up fcron to execute check_system_crontabs. * In this configuration, you're no longer free to edit the systab * at your leisure, at it'll be rewritten the moment the crontabs * are modified.Rebuilding fcron systab.2013-10-19 21:20:38  INFO installing file /tmp/fcrontab.84pova for user systabModifications will be taken into account right now.

Your cron daemon is now configured to automatically run system cron jobs.