improve readme

README.md

@@ -29,17 +29,23 @@ Enter build environment:
 
 Build for x86 (other architectures may come in the future):
  - `make build-x86_64`
+ - If you are using Qemu, please close it before running this command to prevent errors.
 
 To leave the build environment, enter `exit`.
 
 ## Emulate
 
-You can emulate your operating system using [Qemu](https://www.qemu.org/): (Don't forget to add qemu to your path!)
+You can emulate your operating system using [Qemu](https://www.qemu.org/): (Don't forget to [add qemu to your path](https://dev.to/whaleshark271/using-qemu-on-windows-10-home-edition-4062#:~:text=2.-,Add%20Qemu%20path%20to%20environment%20variables%20settings,-Copy%20the%20Qemu)!)
 
  - `qemu-system-x86_64 -cdrom dist/x86_64/kernel.iso`
- - NOTE: When building your operating system, if changes to your code fail to compile, ensure your QEMU emulator has been closed, as this will block writing to `kernel.iso`.
+ - Note: Close the emulator when finished, so as to not block writing to `kernel.iso` for future builds.
 
-Alternatively, you should be able to load the operating system on a USB drive and boot into it when you turn on your computer. (I haven't actually tested this yet.)
+If the above command fails, try one of the following:
+ - Windows: [`qemu-system-x86_64 -cdrom dist/x86_64/kernel.iso -L "C:\Program Files\qemu"`](https://stackoverflow.com/questions/66266448/qemu-could-not-load-pc-bios-bios-256k-bin)
+ - Linux: [`qemu-system-x86_64 -cdrom dist/x86_64/kernel.iso -L /usr/share/qemu/`](https://unix.stackexchange.com/questions/134893/cannot-start-kvm-vm-because-missing-bios)
+ - Alternatively, install a custom BIOS binary file and link it to Qemu using the `-L` option.
+
+Alternatively, you should be able to load the operating system on a USB drive and boot into it when you turn on your computer. (I haven't actually tested this yet, but it appears to be working for others.)
 
 ## Cleanup