vmunix was/is the traditional name of the kernel file in several Unix operating systems.
In Linux, this was changed to
vmlinux and then to
vmlinuz when kernel file compression was added.
Classically, the kernel file might have lived in the root directory, and on some Linux distributions you might still see a symbolic link at
/vmlinuz.old pointing to the current and previous kernel version, respectively. But modern bootloaders can easily handle more than two kernel versions, and the convention has evolved to use
/boot/vmlinuz-<kernel version number>.
When the disk sizes increased and Logical Block Addressing became the norm on IDE disks (between 1994 and 2003), the BIOSes of pre-1994 systems did not always support LBA and so might be able to access only the first 528 MB or so, until a LBA-aware operating system started running. As a result, it was important to be able to place the files required for the earliest phases of boot-up to a separate small partition that could be guaranteed to be at the very beginning of the disk. In Linux, that resulted in the
/boot filesystem convention.
In a nutshell, you'll have the option of creating
/boot as a separate filesystem that will only contain the kernel and
initramfs files of the current and any previous fallback kernel versions, and any files the bootloader itself might need (most commonly the
Although all modern systems understand LBA as a matter of course, the
/boot filesystem convention lives on, as it can also be used to allow the system to boot even if the root filesystem takes a form that is completely unrecognizable to the system firmware, for example:
- an encrypted root filesystem,
- a root filesystem on Linux LVM (easily expandable beyond the limits of any single disk if required, even on-line),
- a root filesystem on a software RAID0 or RAID5 set (not necessarily great ideas for root filesystem unless you have special requirements)
- or a root filesystem on a multi-volume ZFS or BtrFS set.
Some system firmwares do include a built-in check that a recognizable, bootable partition exists before attempting to boot from a HDD, even though the actual bootloader might be capable of booting from non-traditional disk layouts.