(not entirely true, I needed a Windows Virtual machine)
I wanted to run a BIOS Update for my HP ZBook 15u G4. Unfortunately, HP provides updates only for Windows.
Linux users are used to such sorrow - but I will most probably stick back to other vendors in the future, where the Linux support is better.
I've extracted the folders and files and put them into this archive file (Updated 28.02.2018, here is the old file). Download it and extract it directly to you USB device. The folder Hewlett-Packard should be then in the root directory on your flash drive.
Reboot and select the Update options in your BIOS. It will reboot several times. Don't worry, grab a cup of coffee.
My story: How I run the Update without a native Windows on the Laptop
I downloaded the BIOS update from the HP support page for the HP ZBook and installed it in a Windows-Virtual Machine on another computer. Here you can select the creation of a USB stick. So I've created a "recovery" USB stick and copied the BIOS image from the Hewlett-Packard\BIOS\Current folder on the USB stick to the Hewlett-Packard\BIOS\New folder.
Now I rebooted the laptop into the BIOS and selected Update BIOS. The system recognised the Update from the USB stick and could install it.
IMPORTANT: Plug in the power supply during BIOS update. The last thing you want is a power-down during a BIOS update!
Don't worry, during the Update process the laptop boots a few times and shows some weird behaviour. Just let him do. Grab a cup of coffee
So, although it is officially not supported, there is a way of how to update the BIOS on the Laptop.
Update [28.02.2018] - I updated the archive file to the current BIOS vP78_0115 from 01.02.2018. The old file is still available