By following this tutorial, I am able to create a simple efi application that prints hello world when executed from an uefi shell. However, I was wondering how does one creates bootable EFI image. I tried to use bcfg command in the shell and added my efi binary as one of the booting sequence. However, is there anyway to do it without the need of going into the shell?
However, if you are actually building your own firmware, you can also look at creating a bootable EFI image and set your default boot option to this binary. This is most useful if you are including the binary as a part of your ROM, but it might be a little involved to set up the filesystem so that it is seen as a normal boot option.
In this question, Nicholas Embry gave a good answer but I was unable to find any resource to explore further into the topic that he mentioned. Any help would be appreciated. Thanks!
bcfg, just like efibootmgr in Linux, ultimately use the GetVariable() and SetVariable() runtime services (also available during boottime) to modify the system boot configuration.
The UEFI Shell, implementing the bcfg command, is itself a UEFI application. Since its source is publicly available, you can have a look at the implementation of the bcfg command - particularly the BcfgAdd() function.