# HOS System Requirements

HOS requires:

* A 64-bit CPU.
* A UEFI system.
* 128MB of RAM.

# Building HOS

From the top level of the repository, run:

    ./rscons

If you get errors about missing packages, install the packages and then re-run
the build command.

# Running HOS

HOS can run on a physical machine, in VirtualBox, or in QEMU.

## Physical Machine

To install HOS to an EFI partition, follow these steps:

1. Copy build/hello/HOS.EFI to EFI partition EFI/HOS.EFI. For example, from Linux:

    sudo cp build/hello/HOS.EFI /boot/efi/EFI/HOS.EFI

2. Register EFI loader for HOS (one time only) with command:

    efibootmgr -c -d /dev/nvme1n1 -p 2 -l '\EFI\HOS.EFI' -L HOS

(Update the -d device parameter and -p partition parameter as appropriate)

3. Set boot order to desired boot order. Exact order will be system dependent. Example:

    efibootmgr -o 2,0,6,5

At this point you should be able to boot HOS from your EFI boot selection menu.
If you use GRUB, you can optionally create a GRUB boot entry to load HOS.EFI
with an entry like this:

    menuentry 'HOS' {
      insmod part_gpt
      insmod chain
      set root='(hd0,gpt1)'
      chainloader /EFI/HOS.EFI
    }

Just update the root setting for the correction location to your system's EFI
partition.

## VirtualBox

To create a VM in VirtualBox:

1. Build HOS ("./rscons").
2. In VirtualBox, select Machine -> New.
3. Set name to HOS.
4. Set Type to Other.
5. Set Version to Other/Unknown (64-bit).
6. Click Next.
7. Set memory size to 512 MB.
8. Click Next.
9. Select Do not add a virtual hard disk.
10. Click Create.
11. From the HOS repository, create a VirtualBox VMDK image with "./rscons mk-vmdk".
12. Move the HOS.vmdk file generated to the HOS VirtualBox folder.
13. In VirtualBox Manager, open HOS VM settings.
14. Under System, check the Enable EFI checkbox.
15. Under Storage, add a hard disk and browse to select the HOS.vmdk file.
16. To run HOS, either start the VM through VirtualBox or with "./rscons run-vb".

## QEMU

Make sure QEMU is installed (possibly the `qemu-desktop` package). Then:

1. Build HOS ("./rscons").
2. Run `./rscons run` to run HOS in QEMU.