Summary: An overview of the important data structures at the BSP and OAL levels. The BSP data structures are unique in that they are passed between the bootloader and OS, and thus reside in a reserved region of memory. The OAL data structures describe the OAL's 'exports' to the kernel.

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Bootloader Internal Data Structures

On devices with a persistent store, bootloaders typically save configuration information such as the KITL IP address and DHCP settings, debug serial port and launch address. This structure is not standardized, and can be found with different names and forms on different platforms.

These data structures can be thought of as a 'BIOS' information store for CE devices, in the sense that we're configuring parameters of the device, as early as possible in bootup.

The CEPC platform uses a BOOTARGS structure found in @platform\common\src\soc\x86msv1\inc\bootarg.h@. XScale platforms use an EBOOTCFG structure found in @platform\<name>\src\bootloader\eboot\loader.h@.

A typical boot configurations structure looks like this:

		   typedef struct
		   {
		    DWORD [autoDownloadImage;]
		    DWORD IP;
		    DWORD subnetMask;
		    DWORD [numBootMe;]
		    DWORD delay;
		    DWORD [DHCPEnable;]
		    DWORD [bootDeviceOrder;]
		    DWORD [dwPhysStart;]
		    DWORD [dwPhysLen;]
		    DWORD [dwLaunchAddr;]
		    DWORD [dwDbgSerPhysAddr;]
		    DWORD [XmodemDefault;]
		    DWORD [ConfigMagicNumber;]
		    DWORD [dwStoreAddr;]
		    UINT16 RNDISMac[3];
		    DWORD [CheckSignatures;]
		    } EBOOT_CFG, *PEBOOT_CFG;
	

Bootloader Arguments

All platforms have a method to pass information from the bootloader to the kernel. Typically, this structure is filled in by OEMPreDownload before downloading or reading the image from flash.
Although various platforms have different methods of passing arguments, all well-behaved platforms use OALArgsQuery to access this data. If in doubt, search for OALArgsQuery and work backwards.
CEPC uses an X86BootInfo struct located at BOOTARGPTR_LOCATION. OALArgsQuery can be found in @platform\common\src\x86\common\ioctl\devinfo.c@.

SH4,MIPS,and XScale platforms use a BSPARGS struct, located at IMAGESHAREARGSPA_START. OALArgsQuery is found in @platform\<name>\src\oal\oallib\args.c@.

A typical bootloader argument structure looks like this:

		  typedef struct {
		    OAL_ARGS_HEADER header;
		    UINT8 deviceId[16];                 // Device identification
		    OAL_KITL_ARGS kitl;
		    UINT32 [dbgSerPhysAddr;]              // Debug serial physical address
		    UINT8 uuid[16];
		    BOOL [bUpdateMode;]                   // TRUE = Enter update mode on reboot.
		    BOOL [bHiveCleanFlag;]                // TRUE = Clean hive at boot
		    BOOL [bCleanBootFlag;]                // TRUE = Clear RAM, hive, user store at boot
		    BOOL [bFormatPartFlag;]               // TRUE = Format partion when mounted at boot
		    UINT32 [ImageSignedState;]            // enum {IMAGE_NOT_SIGNED, IMAGE_TEST_SIGNED, IMAGE_FINAL_SIGNED}
		  } BSP_ARGS, *PBSP_ARGS; @)
	

Of interest here are the debug serial settings, the KITL settings, and the various boot flags. Note that OEMKitlStartup is able to modify this structure before KITL initialization, so if the OS image seems not to honor KITL settings, investigate there.

OAL Data Structures

*OEMGlobal. This structure can be viewed as the OAL ‘exports’ to the kernel. It contains all of the functions and variables that the OAL is required to implement, such as OEMInit, OEMIOControl, pfnPowerOff, pfnInterruptHandler.
*Several, such as pfnIsROM or pfnSetMemoryAttributes are optional, and can be left as NULL.
*MSDN has the full list available online: http://msdn2.microsoft.com/en-us/library/aa913510.aspx

*NKGlobal. The counterpart to OEMGlobal, these are the kernel functions accessible from the OAL.
*See MSDN: http://msdn2.microsoft.com/en-us/library/aa915982.aspx

*OEMAddressTable (ARM). Usually found in oemaddrtab_cfg.inc, this is a mapping between physical and virtual addresses used during the initialization process. An excellent reference for determining what a pointer is referencing.

*g_KitlDevices. Found on a variety of non-x86 platforms, this structure lists the KITL devices present, along with their transport configuration. This structure is passed to OALKitlInit. For details, consult the MSDN KITL Transport article: http://msdn2.microsoft.com/en-us/library/aa914512.aspx

Further reading:

MSDN – OAL Structures - http://msdn2.microsoft.com/en-us/library/aa914850.aspx

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