On 02/02/2021 17:06, Ard Biesheuvel wrote:

On Tue, 2 Feb 2021 at 17:41, Laszlo Ersek <lersek@redhat.com> wrote:

On 01/29/21 23:45, wernerbuck@gmail.com wrote:

I am network booting the raspberry pi firmware. Unfortunately as its loaded from TFTP it does not retain settings nor do I believe I can give it settings.
I am already compiling my own version of RPi4 uefi with edk-platforms/../Rpi4/.dsc edited for some better defaults like setting higher memory.
However, I can't find an option to force a particular boot option as a default. Right now it tries to boot an .efi locally but that efi is not able to be found because we are booting from TFTP.
Instead I would like it to boot to PXE again where I can boot iPXE and control the boot process further. The end goal here is that I can boot UEFI -> iPXE without an SD card.

Could you help me find out what option/variable I can set in the platform dsc? I think the option should be in MdePkg.dec but I can't find any "DefaultBootOption" or override variable.

I think you might be able to trick the BDS into loading iPXE as the
shell if you set the correct file GUID for it in the right PCD.

I'm interested to know the outcome of this experiment.

Also: the motivation behind creating https://github.com/ipxe/pipxe was because the Pi's VC4 PXE boot code turned out to be incredibly unreliable (with a ~10% boot failure rate) - this is why I personally gave up on getting the Pi to network boot without an SD card as a bootstrap.

Michael