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This article mainly explains "how to start Fedora when Linux kernel runs". The explanation in this article is simple and clear, easy to learn and understand. Please follow the ideas of Xiaobian to study and learn "how to start Fedora when Linux kernel runs".

bios reads the Linux kernel loader located in *** sectors (the master boot record (MBR) of a hard disk or optical disc). The kernel loader loads the kernel. Most of the new releases use the 2.6 series kernel, although the 2.4 series kernel is still widely used. Run the Init process and execute multiple scripts. If Linux is booted from hard disk, the kernel loader (Intel compatible architecture) primarily uses Lilo or Grub. If booting the Linux kernel from a CD, such as a Live CD or installation disk, Syslinux is often chosen as the kernel loader.

In the configuration files/etc/lilo.conf and/boot/grub/grub.conf you can set:

Where the kernel loader is installed (master boot record or boot record for a single partition). Specifies the partition where the system root file system (/) resides. Path to kernel image and initrd. You can configure different operating systems (Linux kernel or other operating systems) and different kernel versions to boot.

Each Linux distribution derives its kernel from the Linus Torvalds kernel, but may have different release mechanisms or non-Linus patches added by the maintainer of the release. You can recompile and install the official kernel code or different distributions of kernel source packages.

The *** processes started by Unix systems are always Init processes, and its configuration file is always/etc/inittab. By analyzing/etc/inittab and all the scripts it sources, you can fully understand the system startup process. The main difference between Linux/Unix is mostly the shell (initialization) script. Many Linux distributions use the Unix System V boot method. Based on rc scripts, start the corresponding scripts under/etc/init.d/according to different runlevels.

RedHat

/etc/rc.d/rc.sysinit is called by the init process, which sets up and executes all system initialization functions and source configuration files in the/etc/sysconfig/* directory./ etc./rc.d/functions Generic functions used by other system scripts. /etc/rc.d/* Startup and shutdown scripts for all system services. When the system starts, execute script files in/etc/rc#runlevel.d/("#runlevel" is the runlevel, generally 1, 3, 5) directory according to the runlevel specified by the user. Note: The script in/etc/rc#runlevel.d/is just a link to the script in/etc/rc.d/.

Fedora -Startup process

Fedora uses Red Hat to boot the system.

Boot Loader

Fedora uses Grub as the boot loader, all configuration files and binaries are in the/boot/grub/directory, grub.conf contains all configuration information (/boot/grub/menu.lst and/etc/grub.conf are links to it), and/boot/grub/splash.xpm.gz is the default background image for grub boot.

Kernel

The main binary file is/boot/vmlinuz-version, the System Map file is/boot/System.map-version, and the file that initializes memory at boot time is/boot/initrd-version. The complete configuration file for the current kernel is/boot/config-version. Kernel modules are located in/lib/modules/version.

Init

/etc/inittab has a rule that mingetty starts before runlevel 1 (so you can use the root shell without a password in single-user mode). Regardless of the runlevel, the *** initialization scripts executed by the system are/etc/rc.d/rc.sysinit, and then execute scripts in the/etc/rc#runlevel.d directory to start various system services. System configuration files are mostly placed under/etc/sysconfig/and sourced during startup.

/etc/rc.d/rc.sysinit is responsible for various startup tasks in the following order

Use initlog to log health, depending on the settings in/etc/initlog.conf and/etc/syslog.conf.

If DEVFS is used, the devfsd service is started. Set hostname, hosttype and load (source)/etc/sysconfig/network Mount procfs and sysfs to/proc and/sys directories

Check SeLinux status load (source)/etc/init.d/functions, which contains generic shell functions used by other scripts, including daemon(), killproc(), pidofproc(), status(), echo_success()(green OK), confirm(), etc., and load (source) other important system configuration files: /etc/sysconfig/i18n,/etc/sysconfig/init, etc.

Set system default font.

Print the familiar "Welcome to... "Flags run graphical startup program rhgb, changing the picture in/usr/share/rhgb directory can customize the startup interface. Configure the kernel according to the settings in/etc/sysctl.conf Set the system clock according to the parameters in the/etc/sysconfig/clock file Configure the keyboard layout according to the settings in/etc/sysconfig/keyboard, and customize the keyboard settings in text mode by changing the settings in the/etc/sysconfig/keyboard file.

Initialize ACPI Settings Initialize

USB controllers and HID devices look at the/fastboot,/fsckoptions,/forcefsck, and/.autofsck files and load (source)/etc/sysconfig/autofsck to determine whether and how to perform file system checks.

Check disk quotas Initialize ISA PNP devices according to/etc/isapnp.conf. Mount the root file system read-write If enabled Start logical volume management (LVM) Activate swap space (swap) Load kernel modules using parameters specified in/etc/modules.conf Boot raid (MD) devices If the/.unconfigured flag file exists, run the system *** times to start the necessary configuration. Delete flag files in/,/var/lock,/var/run directories, delete rpm database files (/var/lib/rpm/__db*) and various files in/tmp directory.

Initialize serial port, SCSI tape, USB memory, Firewire hdparm program to enable hard disk optimization according to the configuration of/etc/sysconfig/harddisks* file. If a network profile exists, activate the default network configuration. After completing the above steps, the system enters the default runlevel and activates services in the/etc/rc#runlevel.d/directory.

***, the system will execute the/etc/rc.local script. Here, users can easily add commands that they want to run at system startup.

Thank you for reading, the above is the "Linux kernel how to start Fedora" content, after the study of this article, I believe that everyone on the Linux kernel how to start Fedora this problem has a deeper understanding, the specific use of the situation also needs to be verified. Here is, Xiaobian will push more articles related to knowledge points for everyone, welcome to pay attention!

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