Hands-on Booting : Learn the Boot Process of Linux, Windows, and Unix

Table of Contents About the Author About the Technical Reviewer Acknowledgments Introduction Chapter 1: Introduction Why? What? The Focus of This Book Power Supply CPU Chapter 2: Multiboot List of Operating Systems Installing the Operating Systems Primary/Logical Partitions Partitioning First OS Installation: XP Boot Sector OpenSolaris 2008 PC-BSD 9.0 Windows Server 2003 Windows 7 Red Hat Enterprise Linux 6 (RHEL 6) Tweaking GRUB Hacking the Windows Bootloaders Fedora 15 Complete Flowchart Unified Extensible Firmware Interface (UEFI) BIOS Limitations UEFI Advantages The GUI of UEFI UEFI Implementation EFI System Partition (ESP) EFI Secure Boot Partition Table List of Operating Systems Ubuntu 18.04 LTS Windows 10 Fedora 31 UEFI Shell Misconceptions About UEFI Misconception 1: UEFI Is a New BIOS or UEFI Is a BIOS Misconception 2: Microsoft Is Evil Linux Vendors Should Make Their Own Key Pair All Linux Vendors Should Make Only One Key Pair Disable UEFI’s Secure Boot Feature Misconception 3: Disable the UEFI Chapter 3: GRUB Bootloader GRUB 2 Implementation GRUB 2 on BIOS-Based Systems /boot/grub2 Device.map grub.cfg i386-pc /etc/default/grub /etc/grub.d/ 10_linux 20_linux_xen 20_ppc_terminfo 30_os_prober 30_uefi-firmware 40_custom and 41_custom GRUB 2 on UEFI-Based System Boot Loader Specification (BLS) Common Bootloader Issues “Can’t Boot” Issue 1 (Bootloader) “Can’t Boot” Issue 2 (Bootloader) Resolution for a BIOS-Based System Resolution for a UEFI-Based System “Can’t Boot” Issue 3 (Bootloader + Kernel) Resolution for BIOS-Based Systems Resolution for UEFI-Based Systems Secure Boot Feature of UEFI 100 OS Multiboot Project A Dummy Small Bootloader GRUB 2 at a Low level Chapter 4: Kernel Loading the Kernel in Memory After Loading the Kernel in Memory Protected Mode Long Mode What Extracts vmlinuz? extract_kernel Inside the Kernel Chapter 5: initramfs Why initramfs? Infrastructure ramfs tmpfs rootfs initramfs Implementation bin Normal Binaries Special Binaries Networking Binaries Hooks Systemd Binaries Sbin Filesystem and Storage-Related Binaries Networking Binaries Special Binaries Basic Binaries etc Virtual Filesystems dev proc and sys usr, var lib, lib64 initramfs Booting How Does the Kernel Extract initramfs from Memory? How Does the Kernel Mount initramfs as Root? Chapter 6: dracut Getting Started Making an initramfs Image Dracut and Modules How Does dracut Select Modules? Customizing initramfs dracut Module or Kernel Module? “Can’t Boot” Issue 4 (initramfs) “Can’t Boot” Issue 5 (initramfs) Kernel Command-Line Options root init ro rhgb and quite selinux dracut Command-Line Options rd.auto (rd.auto=1) rd.hostonly=0 rd.fstab = 0 rd.skipfsck rd.driver.blacklist, rd.driver.pre, and rd.driver.post rd.debug rd.memdebug= [0-4] lvm, raid, and Multipath-Related dracut Command-Line Parameters rd.break and rd.shell Chapter 7: systemd (Part I) Structure How Does systemd Reduce Boot Time? systemd-analyze “Can’t Boot” Issue 6 (systemd) Flow of systemd Inside initramfs systemd-journal.socket dracut-cmdline.service dracut-pre-udev.service dracut-pre-trigger.service systemd-udev-trigger.service local-fs.target swap.target dracut-initqueue.service “Can’t Boot” Issue 7 (systemd + Root LVM) plymouth Installing plymouth Managing plymouth Structure Sysinit.target “Can’t Boot” Issue 8 (sysctl.conf) basic.target dracut-pre-mount.service Chapter 8: Debugging Shells The Shell How Does systemd Drop Us to an Emergency Shell? rescue.service and emergency.service Chapter 9: systemd (Part II) sysroot.mount initrd.target switch_root/pivot_root Switching to the New Root Filesystem on an init-Based System Switching to a New Root Filesystem on a systemd-Based System Chapter 10: Rescue Mode and Live Images Rescue Mode Rescue Mode initramfs “Can’t Boot” Issue 9 (chroot) Rescue Mode of Enterprise Linux Distributions Live Images SquashFS rootfs.img Booting Sequence of a Live Image Index Master the booting procedure of various operating systems with in-depth analysis of bootloaders and firmware. The primary focus is on the Linux booting procedure along with other popular operating systems such as Windows and Unix. Hands-on Booting begins by explaining what a bootloader is, starting with the Linux bootloader followed by bootloaders for Windows and Unix systems. Next, you’ll address the BIOS and UEFI firmware by installing multiple operating systems on one machine and booting them through the Linux bootloader. Further, you’ll see the kernel's role in the booting procedure of the operating system and the dependency between kernel, initramfs, and dracut. You’ll also cover systemd, examining its structure and how it mounts the user root filesystem. In the final section, the book explains troubleshooting methodologies such as debugging shells followed by live images and rescue mode.  On completing this book, you will understand the booting process of major operating systems such as Linux, Windows, and Unix. You will also know how to fix the Linux booting issues through various boot modes. What You Will Learn Examine the BIOS and UEFI firmware  Understanding the Linux boot loader (GRUB) Work with initramfs, dracut, and systemd Fix can’t-boot issues on Linux    Who This Book Is For  Linux users, administrators, and developers.