Linux boot process | Tech Arkit

Linux boot process | Tech Arkit


for more updates click on subscribe and
click on bell button for latest notifications hi friends welcome to Tech
ARKIT YouTube channel my name is Ravi in this video session we are going to
see that Linux boot process like share comment and subscribe
step by step boot process explanation I am going to tell you so but before that
also I have uploaded the similar video using that rhel7 boot process but seems
to be that when you will little bit of bad things like a few of the people they
are unable to understand the language whatever it is used on that that video
so that’s why I am just remaking the same similar video but it’s not going to
be a similar one but it’s a different one so now first of all how the Linux
boot process start and where the Linux actually booting process comes
into the picture example say if you press your server power button then what
happens immediately do a post. POST in the sense “Power On Self Test” in the sense
each component of the hardware they will power on their own in the sense they
will test their own power like okay I am able to switch on myself are not then
what happens okay if all the hardware says okay I am ready to power on then
what happens whenever you press the power button the post completes and
immediately the BIOS program basic input/output system will be loaded from
the hardware like all the details about the hardware and how many devices are
connected all the devices are functioning well or not is there any
errors all the details will come over here about the hardware details so
BIOS will be loaded the next one is that Master Boot Record
so the Master Boot Record is an a very fast record on the hard disk which is
512 bytes in size whenever first read comes to the MBR is that okay here
is my MBR the MBR will be located with the partition information and where my
OS partition is located where is my boot related files will be located the MBR
will guide the system to go there and boot up with the OS process after that
the grub will be loaded the GRUB will be loaded like basically after the MBR
MBR says that ok here is your slash partition boot partition and all the
information about the partitions where they are located after that it finds the
grub in that and in grab what the grub will do is that initial RAMFS INITRAMFS
the files will be extracted into the initial phase as a temporary file
system then the /sysroot will be mounted as a read-only file system then
it will verify all this related file system and kernel then after reading all
these steps and kernel when it’s jumping into the kernel then the hard disk process
starts and the the kernel will be located in the kernel trying to load
that’s where we will get the boot menu like it is asking as for the rhel7
something like that you want to enter like are you press spacebar to wait a
few seconds there itself you can interrupt your kernel boot
process then you can reset the password or whatever you want but if the grub
password is then he out into the grub password and
it enter into the kennel if there is no grub password it directly
from the grub it directly goes to the kernel and kennel will be loaded where
your process get started first of all the systemd the process gets started with
the system fork() call the for call will be executed and fast system because the PID is generated in a round-robin mechanism the first PID for the systemd is going
to be process ID one that’s where the system they will be started the demon of
the systemD will be started then it takes the entire services to load upon
the which target you set as a default example say the target is say a set as a
GUI target or maybe a CLI target and maybe an emergency target or whatever
the target you say it if it isn’t a GUI or CLI then its associated services will
be started on the target one by one and all the services status will be verified
if any fail is there it will retry sometimes if it is not able to retry
then it will skip that one as a it keeps on a failed mode itself and it goes to
the next one then associated required services are
started then the system will be started next the target is going to be load all
the services after that if it is in a GUI enabled then you will see energy UI
interface if it isn’t CLI enabled interface then you can see an a CLI
interface over there that’s how the boot process completes whenever you switch on
your server power on your server post happens and bias will be loaded and next
time is the MBR will be loaded to locate for the various your partition
information and grab information all this stuff then the graph will be look
loaded as an initial Rama phase then the kernel is loaded into the multiple
stages like stage 1 stage 1 point 5 – then the criminal process completes
then it starts the processes from the system D then it loads the associated
target enabled services on the targets will be started and your actual servers
will be loaded that’s about the boot process and crispy
and clear I hope thanks for watching stay tuned please subscribe to the
channel for more upcoming video signed courses please follow us on social
networking site if you have any technical related questions we can ask