On a traditional BIOS PC, the firmware has completed its power-on self test and selected the hard disk as the boot device. What happens next?
LPIC-1 Exam 101-500, objective 101. System architecture medium
Draft — not checked yet. This question was written from the published exam objectives and cites the clause it comes from, but nobody has yet read it against that clause and signed for it.
It is kept out of search results and out of mock exams until they have. Read the source below before you take the answer as settled.
The options
Correct The firmware loads the first sector of the disk into memory and executes the boot loader code it finds there
Correct. BIOS reads the 512-byte MBR from the chosen device and jumps into it. That code is the first stage of the boot loader, which then finds and loads the rest of itself.
Not correct The kernel unpacks the initramfs and runs the scripts inside it
Wrong, that is later. The initramfs only exists in memory once the boot loader has loaded both the kernel and the initramfs image and handed control to the kernel.
Not correct The init process starts as PID 1 and begins starting services
Wrong, that is the last step of the boot. init or systemd is started by the kernel, after the kernel has initialised and mounted a root filesystem.
Not correct The firmware reads /boot/grub/grub.cfg to find out which kernel to load
Wrong. BIOS firmware has no filesystem drivers and cannot read a file such as grub.cfg. Reading that configuration is the boot loader's job once it is running.
Why
The BIOS chain is: firmware POST, boot device selection, MBR boot loader, boot loader loads kernel and initramfs, kernel initialises hardware and mounts the root filesystem, kernel starts PID 1. A UEFI system differs at the front: the firmware understands the FAT EFI System Partition and loads a boot loader file such as grubx64.efi directly, so no MBR code is involved.
Where this comes from
- Cited
- LPI exam objective 101.2
- What it says
- The sequence from firmware through boot loader and kernel to the first userspace process.
Practise this
Reading one question is not practice. The trainer will draw a set from objective 101 and space the ones you get wrong.