c语言 - 带有 RT->GetVariable 的 UEFI 读取变量

Question

我是编码新手。所以我尽量保持简单。我的目标是读取 uefi 变量，如供应商/串行并将其打印回来。我的代码将无法正常工作。我正在使用 gnu-efi。

include "efi.h"
include "efilib.h"
CHAR16*         name;
EFI_GUID*       vendorguid = EFI_GLOBAL_VARIABLE;
UINT32*         attributes;
UINTN*          datasize;
VOID*           data;
EFI_STATUS
EFIAPI
efi_main (EFI_HANDLE ImageHandle, EFI_SYSTEM_TABLE *SystemTable){
        InitializeLib(ImageHandle, SystemTable);
        uefi_call_wrapper(ST->ConOut->SetMode, 2, ST->ConOut, 0);
        uefi_call_wrapper(ST->ConOut->SetAttribute, 2, ST->ConOut, EFI_WHITE | EFI_BACKGROUND_RED);
        uefi_call_wrapper(ST->ConOut->ClearScreen, 2, ST->ConOut);
        RT->GetVariable(L"Product", vendorguid, attributes, datasize, data);
        Print(L"-> %s", data);
        for(;;) __asm__("hlt");
return EFI_SUCCESS;
}

我收到了一堆编译器警告，但它将被编译：

test.c:79:25: note: in expansion of macro 'EFI_GLOBAL_VARIABLE'
 EFI_GUID* vendorguid  = EFI_GLOBAL_VARIABLE;
                         ^~~~~~~~~~~~~~~~~~~
/usr/include/efi/efiapi.h:210:35: warning: excess elements in scalar initializer
     { 0x8BE4DF61, 0x93CA, 0x11d2, {0xAA, 0x0D, 0x00, 0xE0, 0x98, 0x03, 0x2B, 0x8C} }
                                   ^
test.c:79:25: note: in expansion of macro 'EFI_GLOBAL_VARIABLE'
 EFI_GUID* vendorguid  = EFI_GLOBAL_VARIABLE;
                         ^~~~~~~~~~~~~~~~~~~
/usr/include/efi/efiapi.h:210:35: note: (near initialization for 'vendorguid')
     { 0x8BE4DF61, 0x93CA, 0x11d2, {0xAA, 0x0D, 0x00, 0xE0, 0x98, 0x03, 0x2B, 0x8C} }
                                   ^
test.c:79:25: note: in expansion of macro 'EFI_GLOBAL_VARIABLE'
 EFI_GUID* vendorguid  = EFI_GLOBAL_VARIABLE;
                         ^~~~~~~~~~~~~~~~~~~

如果我在设备上执行它，屏幕会变成正确的红色，但不会打印来自变量的数据。只有"->"

Answer 1

您正在使用指针而不是供应商 guid、属性和数据大小的类型，并尝试写入未分配的缓冲区。示例代码以供参考。