warning: assignment makes pointer from integer without a cast

error:

../../../../../../kernel/generic/android_x86_64/arch/x86/kernel/pci-dma.c:105:8: warning: assignment makes pointer from integer without a cast
error, forbidden warning: pci-dma.c:105

solution:

函数声明要在调用之前

否则，未经声明的函数原型一律默认为返回int值

所以，要包含相应的头文件