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Is the kernel loaded into memory?
The entire kernel is loaded into memory at boot, typically along with an initramfs nowadays. (It is still possible to set up a system to boot without an initramfs but that’s unusual on desktops and servers.)
Who loads the kernel?
Grub has its own filesystem drivers. It doesn’t use Linux’s. Grub loads the kernel and initrd into memory according to the Linux kernel boot protocol. A part of the kernel is loaded at a predefined address, and Grub sets some parameters so that the kernel knows where to find the rest.
Where is kernel loaded after booting?
The kernels are located in the /boot directory, along with an initial RAM disk image, and device maps of the hard drives. After the selected kernel is loaded into memory and begins executing, it must first extract itself from the compressed version of the file before it can perform any useful work.
Is it possible to go back to real mode from virtual mode?
Before the release of the 80286, which introduced protected mode, real mode was the only available mode for x86 CPUs; and for backward compatibility, all x86 CPUs start in real mode when reset, though it is possible to emulate real mode on other systems when starting on other modes.
Where does the bootloader start in the Linux kernel?
As we can read in the kernel boot protocol, the bootloader must read and fill some fields of the kernel setup header, which starts at the 0x01f1 offset from the kernel setup code. You may look at the boot linker script to confirm the value of this offset.
How big is the memory in Linux bootloader?
But it only has 16-bit registers, which have a maximum address of 2^16 – 1 or 0xffff (64 kilobytes). Memory segmentation is used to make use of all the address space available. All memory is divided into small, fixed-size segments of 65536 bytes (64 KB).
What are the last two bytes of the bootloader?
The final two bytes of the first sector are 0x55 and 0xaa, which designates to the BIOS that this device is bootable. This will instruct QEMU to use the boot binary that we just built as a disk image.
How does the Linux kernel work on a computer?
Although this is a series of posts about the Linux kernel, we won’t start directly from the kernel code. As soon as you press the magical power button on your laptop or desktop computer, it starts working. The motherboard sends a signal to the power supply device.