EFI Byte Code

• UEFI Standardized Virtual Machine and Programming Standards
• Programming requires the use of efi and efilib headers and a complex linkage to cross compile to the efi binary code.
• The UEFI standard includes the possible use of a shell in the preboot environment.
• EFI binary files start with the symbol efi_main that has two parameters, EFI_HANDLE ImageHandle and EFI_SYSTEM_TABLE *SystemTable.
• The UEFI shell allows for is the execution of:
  • preboot programs,
  • setup, operating system installation,
  • testing of hardware and software,
  • disk utilities, driver diagnostics,
  • configuration modifications,
  • moving files around and between the hard disk, floppy disk, CD-ROM, USB flash devices, and so on,
  • to load a preboot EFI driver in the system (has an .efi suffix) such as network stacks, tcpip drivers,
  • update old drivers in flash memory,
  • load new drivers for plugin cards,
  • and more.
• Intel Manual on EBC writing and spcifications: http://www.uefi.org/sites/default/files/resources/EBC_Driver_Presentation.pdf
• GNU-EFI allows for compiling EFI native binaries across most platforms
  GNU-EFI http://sourceforge.net/projects/gnu-efi/