Nicolas Besson - Microsoft Windows Embedded CE 6.0 Exam Preparation Kit

Driver Globals<\/p> <\/div>

Among other things you can use the Eboot.bib file to reserve a memory section for the boot loader to pass information to the operating system during the startup process. This information might reflect the current state of initialized hardware, network communication capabilities if the boot loader supports Ethernet downloads, user and system flags for the operating system, such as to enable Kernel Independent Transport Layer (KITL), and so on. To enable this communication, the boot loader and operating system must share a common region of physical memory, which is referred to as driver globals (DRV_GLB). The above Eboot.bib listing includes a DRV_GLB mapping. The data that the boot loader passes to the operating system in the DRV_GLB region must adhere to a BOOT_ARGS structure that you can define according to your specific requirements.<\/p>

The following procedure illustrates how to pass Ethernet and IP configuration information from the boot loader to the operating system through a DRV_GLB region. To do this, create a header file in the %_WINCEROOT%\Platform\< BSP Name<\/em> >\Src\Inc folder, such as Drv_glob.h, with the following content:<\/p>

#include <\/code> <\/p>

// Debug Ethernet parameters.<\/code> <\/p>

typedef struct _ETH_HARDWARE_SETTINGS {<\/code> <\/p>

EDBG_ADAPTER Adapter; // The NIC to communicate with Platform Builder.<\/code> <\/p>

UCHAR ucEdbgAdapterType; // Type of debug Ethernet adapter.<\/code> <\/p>

UCHAR ucEdbgIRQ; // IRQ line to use for debug Ethernet adapter.<\/code> <\/p>

DWORD dwEdbgBaseAddr; // Base I/O address for debug Ethernet adapter.<\/code> <\/p>

DWORD dwEdbgDebugZone; // EDBG debug zones to be enabled.<\/code> <\/p>

// Base for creating a device name.<\/code> <\/p>

// This will be combined with the EDBG MAC address<\/code> <\/p>

// to generate a unique device name to identify<\/code> <\/p>

// the device to Platform Builder.<\/code> <\/p>

char szPlatformStri ng[EDBG_MAX_DEV_NAMELEN];<\/code> <\/p>

UCHAR ucCpuId; // Type of CPU.<\/code> <\/p>

} ETH_HARDWARE_SETTINGS, *PETH_HARDWARE_SETTINGS;<\/code> <\/p>

// BootArgs - Parameters passed from the boot loader to the OS.<\/code> <\/p>

#define BOOTARG_SIG 0x544F4F42 // "BOOT"<\/code> <\/p>

typedef struct BOOT_ARGS {<\/code> <\/p>

DWORD dwSig;<\/code> <\/p>

DWORD dwLen; // Total length of BootArgs struct.<\/code> <\/p>

UCHAR ucLoaderFlags; // Flags set by boot loader.<\/code> <\/p>

UCHAR ucEshellFlags; // Flags from Eshell.<\/code> <\/p>