UEFI 基础教程 （十四） - 设置默认启动项为UEFI Shell

一 编写源代码
OvmfPkg/Library/PlatformBootManagerLib/BdsPlatform.c

UINTN
BootOptionPriority (
CONST EFI_BOOT_MANAGER_LOAD_OPTION *BootOption
)
{
DEBUG ((EFI_D_ERROR," [CSDN] BootOptionPriority %S .\n", BootOption->Description));

if (StrCmp (BootOption->Description, L"Boot Device List") == 0) {
return 4;
}

//
// Make sure Shell is last
//
if ( StrStr (BootOption->Description, L"EFI Internal Shell" ) != NULL) {
return 1;
}
return 30;
}

/**

GC_TODO: add routine description@param Left  - GC_TODO: add arg description
@param Right - GC_TODO: add arg description@retval (BOOLEAN) (BootOptionPriority (Left) < BootOptionPriority (Right)) - GC_TODO: add retval description

**/

INTN
EFIAPI
CompareBootOption (
IN CONST VOID *Buffer1,
IN CONST VOID *Buffer2
)

{
return (BOOLEAN) (BootOptionPriority ((EFI_BOOT_MANAGER_LOAD_OPTION *) Buffer1) > BootOptionPriority ((EFI_BOOT_MANAGER_LOAD_OPTION *) Buffer2));
}

VOID
EFIAPI
PlatformBootManagerAfterConsole (
VOID
)
{
//
// Register UEFI Shell
//
PlatformRegisterFvBootOption (
&gUefiShellFileGuid, L"EFI Internal Shell", LOAD_OPTION_ACTIVE
);

…

//Add default boot first option as uefi shell
DEBUG ((EFI_D_ERROR," [CSDN]: EfiBootManagerSortLoadOptionVariable before.\n"));
EfiBootManagerSortLoadOptionVariable (LoadOptionTypeBoot, CompareBootOption);
DEBUG ((EFI_D_ERROR," [CSDN]: EfiBootManagerSortLoadOptionVariable after.\n"));
…

}

二、 编译生成EFI文件 & 运行

设置Shell为默认启动项后，BIOS启动会优先加载Shell（对于OVMD而言就不用等待前面的PXE、QEMU USB加载了， 可以节省时间）。 当然如果需要设置其他的启动项为默认项，只需要修改BootOptionPriority 中 StrCmp (BootOption->Description, L"EFI Internal Shell")为 StrCmp (BootOption->Description, L"XXXX")。