Zusammenfassung der Ressource
101.2 BootSystem 2
- GRUB
(Grand
Unified
Bootloader).
- Called by
BIOS or
UEFI
- Display a
list of SO
for boot
- GRUB menu choose
kernels pass new
parameters
option=Value.
- acpi=off
- Enables/disables
ACPI support.
- ACPI "Advanced
Configuration and
Power Interface
- , convierte la
pulsación del botón
de apagado en un
simple evento
- asignar IRQ
a los
dispositivos.
- init=/bin/bash
- systemd.unit=graphical.target
- Accept
Runlevel
1,S
- Mem=512M
- used VM
- maxcpus=2
- Used VM
- quiet
- Hide boot mssages
- vga=ask
- will show a list of the
available modes of video
- root=/dev/sda3
- Sets the root partition,
distinct from the one
pre-configured in the
bootloader.
- rootflags
- options root FS
- ro
- root FS only Read
- rw
- writing in root FS
during initial
mount
- Changing the
kernel parameters
is not usually
required
- can be useful to detect
and solve operating
system related
problems
- /etc/default/grub
- add Parameters Kernel in
line GRUB_CMDLINE_LINUX
- A new configuration file for the
bootloader must be generated
every time /etc/default/grub
changes,
- grub-mkconfig -o
/boot/grub/grub.cfg
- read in /proc/cmdline
- System
Initialization
- Kernel
- scripts
- services o daemons
- Configuration File
- SO starts when the
bootloader loads
the kernel into
RAM.
- Basic hardware
configuration
and memory
addressing
- initramfs (initial
RAM filesystem).
- 1.- Containing a filesystem
used as a temporary
root filesystem during
the boot process.
- 2.- The main purpose of a initramfs file is to
provide the required modules so the kernel
can access the “real” root filesystem of the
operating system.
- 3.- As soon as the root filesystem is
available, the kernel will mount all
filesystems configured in /etc/fstab and
then will execute the first program, a
utility named init
- The init program is responsible
for running all initialization
scripts and system daemons.
- SysV standard
- the concept of
runlevels.
Runlevels are
numbered 0 to 6
- systemd
- employs sockets and D-Bus for service
activation, on-demand daemon execution,
process monitoring with cgroups, snapshot
support, system session recovery, mount
point control and a dependency-based
service control
- Upstart
- Like systemd,
Upstart is a
substitute to
init.
- The focus of Upstart is to speed
up the boot process by
parallelizing the loading process
of system services
- Initialization
Inspection
- Errors may occur
during the boot
process,
- kernel ring
buffer.
- The memory
space where
the kernel
stores its
messages
- dmesg
dmesg
--clear
- Ver y
Limpiar
Messages
- Systemd
- journalctl journalctl -b
journalctl --list-boots
journalctl -b 0
- /var/log
- store other
messages
- journalctl -d /var/log/journal