Coping files to Efi Shell throu network

Question

I have a question, Is it possible to copy file to efi using some sort of protocol?

Example I am having computer and virtual machine, virtual machine boots to efi and I need to copy file on it and then execute it in efi environment.

Is it possible?

Answer 1

If you just want to execute a remote EFI binary, look for the "rload" command if its available in your EFI shell.

This uses TFTP. And this assume your EFI has network drivers and all.

In my shell, haven't found a command to actually copy the remote file to the filesystem, which is kind of annoying.

Answer 2

Well, when i started developing EFI applications, i found the same problem. How to send file on EFI environment? For now i know these ways:

1. USB storage device.

Probably the easiest way if you copy files not too often. Just put files on USB flash drive and connect it to virtual machine (VM).

To access file from EFI environment you need EFI shell or something like that. VMware already has integrated shell, while on other VMs you may need to obtain it. To do this you can use wonderful rEFInd Boot Manager, which contains shell. Unzip it, insert iso image in VM's CD-ROM and boot from it. In the rEFInd menu choose "Start EFI Shell". You will see command prompt, where all storage devices mapped as FS0, FS1,... If you see only FS0 (rEFInd file system), then you probably forgot to connect USB drive to VM.

Now to get your file just type commands like this:

fs1:
cd directory_with_file

All shell commands can be found by help command.

2. Transfer via TFTP.

Longer to setup, faster to use. Nice if you send files often, while developing EFI applications for example. For this method you need TFTP server like tftpd-hpa working (it could be on your host machine), EFI Shell + TFTP client on your VM. There is plenty information about starting TFTP server, so you can find manual yourself. Also it is nice to have DHCP server (it is optional, but configuration will be much easier with DHCP).

TFTP client can be built from Tianocore sources or downloaded as x64 precompiled binary from my cloud (i dont know why Tianocore maintainers do not provide it in binary). Put tftp.efi on your VM somewhere you can access it (USB drive or virtual HDD). Put your file in TFTP root directory (like /srv/tftp). Probably you should turn your VM's network adapter into bridge mode, so it has real ip, if you want to use DHCP. Start EFI shell VM as described above. When you see command prompt, type these commands.

ifconfig -s eth0 dhcp
fs1:
cd destination_directory
tftp 192.168.3.1 file_to_copy

Where:

• eth0 is your network adapter, you can find required one with ifconfig -l. Also you can use static ip instead of dhcp, see help ifconfig
• fs1: is your file system with tftp.efi, it could be fs0: or other depends on your booting device
• tftp is tftp.efi app, 192.168.3.1 is ip address of TFTP server (host machine or real server)

Also you can write this commands in startup.nsh file in the root of your bootable file system to do it on VM loading. Or only last line in another *.nsh script file to download while EFI running.

3. QEMU virtual machine

It is very handy for simple testings, you do not need TFTP, DHCP, USB drive, etc. If it is ok to recreate VM each time you boot, there is wonderful article about creating and debugging EFI applications with QEMU on osdev.org.