In previous lesson we've developed an app that showed us current boot options: ``` FS0:\> ShowBootVariables.efi Boot0000 UiApp Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331) Boot0001 UEFI QEMU DVD-ROM QM00003 PciRoot(0x0)/Pci(0x1,0x1)/Ata(0x0) Boot0002 UEFI QEMU HARDDISK QM00001 PciRoot(0x0)/Pci(0x1,0x1)/Ata(0x0) Boot0003* EFI Internal Shell Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(7C04A583-9E3E-4F1C-AD65-E05268D0B4D1) Boot0004 UEFI PXEv4 (MAC:525400123456) PciRoot(0x0)/Pci(0x3,0x0)/MAC(525400123456,0x1)/IPv4(0.0.0.0) ``` If you want to know information about the printed GUIDs here it is: - `FILE_GUID = 7C04A583-9E3E-4f1c-AD65-E05268D0B4D1 # gUefiShellFileGuid` https://github.com/tianocore/edk2/blob/master/ShellPkg/Application/Shell/Shell.inf - `FILE_GUID = 462CAA21-7614-4503-836E-8AB6F4662331` - UiApp module is driver for BDS phase https://github.com/tianocore/edk2/blob/master/MdeModulePkg/Application/UiApp/UiApp.inf As for the `7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1` it is a GUID for the firmware volume in our OVMF image. https://github.com/tianocore/edk2/blob/master/OvmfPkg/OvmfPkgX64.fdf This *.fdf file lists what drivers/apps are placed in every volume in the image (this includes volumes for SEC, PEI or DXE stages): ``` ... [FV.SECFV] FvNameGuid = 763BED0D-DE9F-48F5-81F1-3E90E1B1A015 BlockSize = 0x1000 FvAlignment = 16 ... INF <...> ... [FV.PEIFV] FvNameGuid = 6938079B-B503-4E3D-9D24-B28337A25806 BlockSize = 0x10000 FvAlignment = 16 ... INF <...> ... [FV.DXEFV] FvForceRebase = FALSE FvNameGuid = 7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1 ### <---- this is a GUID from our output BlockSize = 0x10000 FvAlignment = 16 ... INF ShellPkg/Application/Shell/Shell.inf <--- this apps are placed in the FV.DXEFV firmware volume ... INF MdeModulePkg/Application/UiApp/UiApp.inf ``` For the complete edk2 FDF file specification look at the https://edk2-docs.gitbook.io/edk-ii-fdf-specification/ If you look at the https://github.com/tianocore/edk2/blob/master/ShellPkg/Application/Shell/Shell.inf you'll see that EFI Shell is a simple `UEFI_APPLICATION`. We've developed a lot of those in these lessons, so let's try to add one of our apps to boot options. We will try to add our `HelloWorld` application to the boot options. We will look at how Shell app is included and try to do the same. First we need to add our app to OVMF image. So let's add `UefiLessonsPkg/HelloWorld/HelloWorld.inf` to the `[FV.DXEFV]` section next to `INF ShellPkg/Application/Shell/Shell.inf` in a `OvmfPkg/OvmfPkgX64.fdf b/OvmfPkg/OvmfPkgX64.fdf` we've already discussed. ``` [FV.DXEFV] FvForceRebase = FALSE FvNameGuid = 7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1 BlockSize = 0x10000 FvAlignment = 16 ... INF ShellPkg/Application/Shell/Shell.inf + INF UefiLessonsPkg/HelloWorld/HelloWorld.inf ... ``` If we try to build OVMF now we would get: ``` $ build --platform=OvmfPkg/OvmfPkgX64.dsc --arch=X64 --buildtarget=RELEASE --tagname=GCC5 ... build.py... : error F001: Module /home/kostr/tiano/edk2/UefiLessonsPkg/HelloWorld/HelloWorld.inf NOT found in DSC file; Is it really a binary module? ... ``` Ok, so we need to add information to the `OvmfPkg/OvmfPkgX64.dsc` file. If you look at this file, you'll see that `ShellPkg/Application/Shell/Shell.inf` is listed under `[Components]` section. We've already used it in our first lesson when we've tried to compile our app without package. Add `UefiLessonsPkg/HelloWorld/HelloWorld.inf` next to the Shell INF file. ``` [Components] ... ShellPkg/Application/Shell/Shell.inf { ... } + UefiLessonsPkg/HelloWorld/HelloWorld.inf ... ``` Shell.inf file has some information inside the brackets `{...}`. Don't mind it, we don't need such info for our simple `HelloWorld.inf`. Now we can compile OVMF without errors: ``` $ build --platform=OvmfPkg/OvmfPkgX64.dsc --arch=X64 --buildtarget=RELEASE --tagname=GCC5 ``` Our `HelloWorld` app would be compiled and embedded in the OVMF image but unfortunately in wouldn't be listed in a boot options. When we used our `ShowBootVariables.efi` app we saw that UEFI shell boot option had a description `EFI Internal Shell`. Let's try search for that in a edk2 codebase: ``` $ grep "EFI Internal Shell" -r ./ --exclude=Build ./ArmVirtPkg/Library/PlatformBootManagerLib/PlatformBm.c: &gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE ./OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c: &gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE ./OvmfPkg/Library/PlatformBootManagerLibBhyve/BdsPlatform.c: &gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE ./OvmfPkg/Library/PlatformBootManagerLibGrub/BdsPlatform.c: &gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE ``` For our case we're interested in a `./OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c` file: ``` VOID EFIAPI PlatformBootManagerAfterConsole ( VOID ) { ... // // Register UEFI Shell // PlatformRegisterFvBootOption ( &gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE ); ... } ``` If you grep for a `gUefiShellFileGuid`: ``` ./OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c: &gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE ./OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf: gUefiShellFileGuid ./ShellPkg/Application/Shell/Shell.inf: FILE_GUID = 7C04A583-9E3E-4f1c-AD65-E05268D0B4D1 # gUefiShellFileGuid ./ShellPkg/ShellPkg.dec: gUefiShellFileGuid = {0x7c04a583, 0x9e3e, 0x4f1c, {0xad, 0x65, 0xe0, 0x52, 0x68, 0xd0, 0xb4, 0xd1}} ``` Ok it looks like we need to create a `UefiLessonsPkg/UefiLessonsPkg.dec` file with something like `gHelloWorldFileGuid` with a value equal to the one that is listed in a `UefiLessonsPkg/HelloWorld/HelloWorld.inf` file. Let's do it: ``` [Defines] DEC_SPECIFICATION = 0x00010005 PACKAGE_NAME = UefiLessonsPkg PACKAGE_GUID = 7e7edbba-ca2c-4177-a3f0-d3371358773a PACKAGE_VERSION = 1.01 [Guids] # FILE_GUID as defined in UefiLessonsPkg/HelloWorld/HelloWorld.inf gHelloWorldFileGuid = {0x2e55fa38, 0xf148, 0x42d3, {0xaf, 0x90, 0x1b, 0xe2, 0x47, 0x32, 0x3e, 0x30}} ``` EDK2 Package Declaration (DEC) File Format Specification can be found at link https://edk2-docs.gitbook.io/edk-ii-dec-specification/ Let's add our GUID to the `OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf` file ``` [Guids] ... gUefiShellFileGuid + gHelloWorldFileGuid ``` So we could use it in a `OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c` file: ``` VOID EFIAPI PlatformBootManagerAfterConsole ( VOID ) { ... // // Register UEFI Shell // PlatformRegisterFvBootOption ( &gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE ); // // Register HelloWorld app // PlatformRegisterFvBootOption ( &gHelloWorldFileGuid, L"Hello World", LOAD_OPTION_ACTIVE ); ... } ``` If we try to build OVMF now we would get an error: ``` $ build --platform=OvmfPkg/OvmfPkgX64.dsc --arch=X64 --buildtarget=RELEASE --tagname=GCC5 ... build.py... /home/kostr/tiano/edk2/OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf(87): error 4000: Value of Guid [gHelloWorldFileGuid] is not found under [Guids] section in /home/kostr/tiano/edk2/MdePkg/MdePkg.dec /home/kostr/tiano/edk2/MdeModulePkg/MdeModulePkg.dec /home/kostr/tiano/edk2/SourceLevelDebugPkg/SourceLevelDebugPkg.dec /home/kostr/tiano/edk2/OvmfPkg/OvmfPkg.dec /home/kostr/tiano/edk2/SecurityPkg/SecurityPkg.dec /home/kostr/tiano/edk2/ShellPkg/ShellPkg.dec ... ``` To correct in we need our newly created `UefiLessonsPkg/UefiLessonsPkg.dec` to the `OvmfPkg/Library/PlatformBootManagerLib/PlatformBootManagerLib.inf`: ``` [Packages] ... ShellPkg/ShellPkg.dec UefiLessonsPkg/UefiLessonsPkg.dec ``` Finally we can successfully build OVMF. Let's run it and test our newly created boot option. Execute QEMU launch as usual. Now if you'll execute our `ShowBootVariables.efi` app you would get: ``` FS0:\> ShowBootVariables.efi Boot0000 UiApp Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(462CAA21-7614-4503-836E-8AB6F4662331) Boot0001 UEFI QEMU DVD-ROM QM00003 PciRoot(0x0)/Pci(0x1,0x1)/Ata(0x0) Boot0002 UEFI QEMU HARDDISK QM00001 PciRoot(0x0)/Pci(0x1,0x1)/Ata(0x0) Boot0003* EFI Internal Shell Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(7C04A583-9E3E-4F1C-AD65-E05268D0B4D1) Boot0004 Hello World Fv(7CB8BDC9-F8EB-4F34-AAEA-3EE4AF6516A1)/FvFile(2E55FA38-F148-42D3-AF90-1BE247323E30) Boot0005 UEFI PXEv4 (MAC:525400123456) PciRoot(0x0)/Pci(0x3,0x0)/MAC(525400123456,0x1)/IPv4(0.0.0.0) ``` Hooraay! Our boot option is present in the system. Just in case I've placed `Ovmf.diff` in this lesson folder that shows all the necessary changes.