How to setup Linux and Windows boot?

Question

linux

Kali linux is installed on the computer, then windows 8.1, Windows loads quietly, but I can’t enter kali. In kali, sections are divided into "/", "/home" and "/tmp".

Answer 1

Installation sequence, Kali would install GRUB and there would be a choice. And so Windows jammed the bootloader.
Solution - Install GRUB
Boot from a flash drive Kali -Live
Mount the partition with Linux
to execute after reading the manual and correcting it for your configurationgrub-install --root-directory=/mnt /dev/sda

Answer 2

Kali linux installed on the computer then windows 8.1,

Instead of it is necessary to put Windows never after Linux.
It's goofy...
It greatly depends on what type of boot is installed (in Setup) on your computer: BIOS or UEFI.
But, in the general case (albeit in different ways), you need, as they said, to restore the GRUB bootloader.