CsmBlockIo

Function Table

Address	Name	Description
	CsmAssert
	CsmDebugPrint
	CsmCheckDebugLevel
	CsmMatchGuid
	CsmReverseQword
	CsmZeroMem
	CsmGetCurrentAllocation
	CsmLegacyRegionAllocate
	CsmBbsTableCopy
	CsmBbsTableAllocate
	Int13SaveState
	Int13RestoreState
	Int13GetStatus
	Int13ErrorStub
	Int13ReadWriteChs
	Int13ExtendedRead
	Int13ChsReadWrite
	Int13ExtendedWrite
	DiskInfoIdentify
	CsmDiskInfoHandler
	CsmBlockIoEntryPoint
	CsmBlockIoInitDevice
	CsmBlockIoCloseDevice
	CsmFindInIplDt
	CsmInitInt13Handler
	Int13IdentifyDevice
	Int13GetDriveParameters
	Int13ChsGeometry
	BbsDeviceTypeBuilder
Global	Data
Protocol	GUID definitions (.rdata section)
EFI_GUID	gEfiLegacyInterruptProtocolGuid = EFI_LEGACY_INTERRUPT_PROTOCOL_GUID; // 0x3270
0x3250	EFI_GUID gCsmBlockIoInternalGuid = EFI_CSM_BLOCK_IO_INTERNAL_GUID; // 0x3260
0x3280	EFI_GUID gEfiLegacyRegionProtocolGuid = EFI_LEGACY_REGION_PROTOCOL_GUID; // 0x3290
0x32F0	EFI_GUID gEfiLegacyBiosPlatformProtocolGuid = EFI_LEGACY_BIOS_PLATFORM_PROTOCOL_GUID; // 0x3300
0x3310	EFI_GUID gEfiLegacyMbrProtocolGuid = EFI_LEGACY_MBR_PROTOCOL_GUID; // 0x32D0
Protocol	GUIDs installed by this driver
EFI_GUID	gEfiDiskInfoProtocolGuid = EFI_DISK_INFO_PROTOCOL_GUID; // 0x32B0
0x32E0	EFI_GUID gEfiLegacyBiosProtocolGuid = EFI_LEGACY_BIOS_PROTOCOL_GUID; // 0x32C0
HOB	list pointer (cached, from DxeHobLib)
VOID	*mHobList = NULL; // 0x33B8
Debug	output driver handle (from sub_275C)
VOID	*mDebugOutputHandle = NULL; // 0x33B0
UINT8	mCmosScratchRegister = 0; // 0x33D8
INT13	handler state save/restore
UINT32	mInt13SavedEflags = 0; // 0x33DC
Temporary	buffer for INT13 data transfer
VOID	*mInt13TransferBuffer = NULL; // 0x33E0
Segment	for INT13 data transfer
UINT16	mInt13TransferSegment = 0; // 0x33E8
0x33F0	//
Contains	a CRC/checksum and function pointers for internal dispatch
typedef	struct {
Describes	the legacy BIOS extension protocol interface
Default	BBS type value
UINT32	mDefaultBbsType = 0x4FF7F; // 0x3378
IPLDT	handle allocation counter
UINT64	mIplDtHandleCounter = 0; // 0x3380
Reference	count for the IPLDT allocation (sub_FA8)
UINT64	mIplDtRefCount = 0; // 0x3388
Dispatch	table pointer (off_3330 = &mDispatchTable)
LegacyBiosExt	pointer (off_3360 = &mLegacyBiosExtTable)
Library	Helpers
sub_2824	-- Debug assert helper
Calls	gDebugOutput->DebugAssert(FileName, LineNumber, Description)
VOID	EFIAPI
sub_27DC	-- Debug print helper (log with format)
sub_275C	-- Get debug output protocol handle
Locates	the EFI_DEBUG_OUTPUT_PROTOCOL (at 0x3240) from the HOB list
VOID	*
Locate	debug protocol from HOB
if	(EFI_ERROR (gBS->LocateProtocol (
0x3240	NULL
sub_2864	-- Check CMOS scratch register for debug level
Reads	CMOS offset 0x4B, checks debug enable bit
UINT32	CsmCheckDebugLevel (
sub_28B4	-- Get HOB list pointer (DxeHobLib)
sub_2B2C	-- Compare GUID at HOB entry with target guid
BOOLEAN	CsmMatchGuid (
0x32A0	*V2 = CsmReverseQword ((UINT64 )TargetGuid);**
0x32A8	*V2 = CsmReverseQword ((UINT64 )((UINT8* )TargetGuid + 8));**
sub_2B9C	-- Reverse 8 bytes for GUID comparison
UINT64	CsmReverseQword (
sub_2C20	-- ZeroMemory
VOID	CsmZeroMem (
sub_2C80	-- Memory copy (overlap-safe)
Handle	overlapping buffers
OverlapReversed	= FALSE;
Aligned	copy (8-byte aligned)
AlignCheck	= (UINTN)S & 7;
sub_29B8	-- Get current allocation position from legacy region
Walks	a header-terminated chain of blocks starting at the
legacy	region memory buffer. Each block has 4-byte header:
byte0	= type (0xFF = end, 0x00 = unused)
byte1	= 0x7F marker
Returns	the total payload size allocated so far (skip 4-byte header).
UINT64	CsmGetCurrentAllocation (
Check	for end-of-table or unused entry marker
if	(Ptr[0] == 0x7F && Ptr[1] == 0xFF) {
End	marker found	return total + 4 (skip header)
return	Total + 4;
sub_298C	-- Allocate boot services data pool
Wrapper	for gBS->AllocatePool (EfiBootServicesData, Size, &Buffer)
UINT64	CsmLegacyRegionAllocate (
sub_2AE4	-- Allocate and copy a BBS type table to boot services data pool
UINT64	CsmBbsTableCopy (
sub_2A0C	-- Legacy region allocation wrapper
If	pBbsType is provided, allocate and copy the BBS type table.
If	NULL, free the allocation.
UINT64	CsmBbsTableAllocate (
INT13	Subsystem: State Save/Restore
sub_26F4	-- Save current interrupt state for a device
Saves	global INT13 eflags into the per-device saved-flags array
then	replaces it with the device's current flags value.
The	saved-flags array is indexed by the device number stored at
UINT8	Int13SaveState (
Save	current global eflags into the per-device slot
mInt13SavedEflags	= Private->Int13SavedFlags[FlagsIndex];
Replace	with device's current flags
sub_2734	-- Restore previous interrupt state for a device
Restores	the global INT13 eflags value from the per-device saved array.
UINT8	Int13RestoreState (
Restore	saved eflags from the per-device slot
INT13	Handler Functions
sub_1AB0	-- INT13h disk I/O status check (function 0x01)
EFI_STATUS	Int13GetStatus (
reload	context+0x89
sub_1AAC	-- INT13h error handler (stub)
VOID	Int13ErrorStub (
empty	-- placeholder for Int13Error function pointer
sub_1B48	-- INT13h Read Sectors (CHS mode, function 0x02)
Used	when device has CHS geometry (original IDE/ATA)
EFI_STATUS	Int13ReadWriteChs (
Build	INT13 CHS packet
extended	read
Disk	changed	re-detect geometry
Copy	data from transfer buffer
if	(mCommand == 0x02) // read
sub_1E18	-- INT13h Extended Read (function 0x42)
For	LBA mode with extended INT13 support (EDD-1.1+)
EFI_STATUS	Int13ExtendedRead (
Build	extended INT13 packet
First	copy data into transfer buffer, then issue INT13
if	(Command == 0x03) { // write
sub_2104	-- INT13h CHS read/write (traditional CHS, function 0x02/0x03)
EFI_STATUS	Int13ChsReadWrite (
Convert	LBA to CHS
SectorsPerHead	= Private->Sectors + 1;
Retry	loop (up to 3 attempts)
Retry	= 3;
sub_23E8	-- INT13h Extended Write (function 0x43), Verify (0x44)
EFI_STATUS	Int13ExtendedWrite (
Copy	data to transfer buffer first for write
CsmMemCopy	*((VOID )mInt13TransferBuffer, (VOID* )CurrentBuf, TransferBytes);**
Disk	Info Protocol: Inquiry and Identify
sub_1554	-- EFI_DISK_INFO.inquiry
EFI_STATUS	EFAPI
sub_1564	-- EFI_DISK_INFO.Identify
Legacy	BIOS Protocol / INT13 Dispatch
sub_4C8	-- Legacy Disk Info handler (first entry point)
Handles	the EFI_DISK_INFO_PROTOCOL interface for identifying disk types
and	locating the appropriate legacy block I/O region.
EFI_STATUS	CsmDiskInfoHandler (
Locate	the Legacy Interrupt protocol
Status	= gBS->LocateProtocol (
Open	the Block I/O protocol on this handle
Status	= gBS->OpenProtocol (
Determine	if Legacy BIOS Platform protocol is available
Check	for Legacy MBR
Read	MBR and check for boot signature
LegacyRegion	= Private->LegacyRegion;
offset	60, // bytes
count	&DeviceType
Check	device type
if	(DeviceType <= 0x0D) {
Set	BBS device type from IPLDT table
Read	transfer buffer base
Set	transfer buffer flags
preserve	bits 8-10
Initialize	INT13 handler entry
Get	BBS device table
Count	active BBS entries
for	(Index = 0; Index < 256; Index++) {
Execute	INT13 to discover drives
Status	= Private->BbsTable->Execute (
Count	post-INT13 BBS entries
Allocate	BBS entry table in legacy region
if	(mIplDtHandleCounter == 0) {
Close	protocols and return error
Entry	Point
Save	global protocol pointers
gImageHandle	= ImageHandle;
Initialize	HOB list
GetHobList	();
Install	three protocol interfaces on the image handle:
return	gBS->InstallMultipleProtocolInterfaces (
offf3330	- dispatch table with sub_4C8, sub_6D4, sub_FA8
off_3360	- legacy bios ext table
no	interface (protocol-only notification)
sub_6D4	-- Main INT13 handler / CSM Block I/O initialization per device
Called	for each disk device that needs CSM legacy support.
a1	*- Private context (CSM_BLOCK_IO_PRIVATE )**
a2	- EFI_HANDLE for the block device
EFI_STATUS	CsmBlockIoInitDevice (
Initialize	state
CsmZeroMem	(BbsBitmap, sizeof(BbsBitmap));
Locate	Legacy Interrupt protocol
Locate	Legacy 8259 protocol
Open	Block I/O protocol on this handle
Try	Legacy Bios Platform protocol (optional)
Open	for Legacy MBR too
Legacy	MBR is available	read device type via Legacy Region
Get	transfer buffer base from legacy region (offset 4)
Configure	transfer buffer flags (mask 0x700)
Call	BIOS INT13 handler entry
Status	= Private->BbsTable->Init (
Get	BBS table
Status	= Private->BbsTable->GetTable (
Count	current BBS entries
sub_FA8	-- Close / Cleanup INT13 for a device
Called	when a device handle is removed or when shutting down CSM
block	I/O legacy support.
EFI_STATUS	CsmBlockIoCloseDevice (
Decrement	reference count on IPLDT allocation
if	(--mIplDtRefCount == 0) {
Process	each device handle
for	(Index = 0; Index < DeviceCount; Index++) {
Open	Disk Info protocol on the child handle
If	Legacy BIOS Platform is available, transfer to it
if	(PlatformAvailable) {
Free	the INT13 handler's memory
Install	the protocol interface on the child handle
Status	= gBS->InstallProtocolInterface (
Set	legacy region flags
If	Platform is not available, close BlockIo
if	(!PlatformAvailable) {
Final	cleanup
sub_1468	-- Find device in IPLDT (Legacy Device Table)
Searches	the IPLDT for a matching bus:device tuple and sets
the	device index.
VOID	CsmFindInIplDt (
Bus	number
IPLDT_ENTRY_SIZE	}
sub_1570	-- INT13 handler initialization
Called	to set up INT13 handler function table for a device.
BOOLEAN	CsmInitInt13Handler (
Initialize	the media descriptor pointer and INT13 saved state array
Set	signature based on system table revision
if	(gST->Hdr.Revision < 0x2001F) {
Identify	and set up drive parameters
if	*(!Int13IdentifyDevice (Private, (UINT8 )&Private->DeviceInfo)) {**
LBA	device	use extended INT13
Only	support 512-byte sectors
if	(Private->BlockSize != 512) {
Set	up INT13 handler function table
Extended	INT13 device	use LBA handlers
sub_16B0	-- Identify device parameters via INT13
Issues	INT13 function 0x13 to get drive parameters
BOOLEAN	Int13IdentifyDevice (
Sectors	(UINT16 )&DeviceInfo[28] = (UINT16)(
Heads	return TRUE;
Sectors	(UINT16 )&DeviceInfo[28] = (UINT16 )&DeviceInfo[11]; // Cylinders
Heads	if (DeviceInfo[27]) {
sub_1784	-- Get extended drive parameters (INT13 function 0x48)
For	EDD-3.0 compatible devices, retrieves full geometry.
BOOLEAN	Int13GetDriveParameters (
parameter	packet size (41h)
signature	DriveParams[1] = 8;
sector	size low
DMA	DriveParams[6] = DriveParams[1] & 8; // LBA
removable	DriveParams[3] = DriveParams[1] & 1; // extended INT13
Get	CHS geometry from INT13 function
sub_1834	-- Get CHS geometry from INT13 (function 0x08 or ATA identify)
BOOLEAN	Int13ChsGeometry (
Initialize	CMOS parameter table for geometry decode
Set	up INT13 function 0x08 parameter block
ParamPacket	= 'O'; // 79
72	(UINT16 )(mInt13TransferSegment2 + 32) = 74;
Success	-- read geometry from transfer buffer
Heads	DriveParams[27] = DriveParams[44]; // Sectors
Decode	CHS from function 0x08 response
if	(FunctionCode != 10) {
Calculate	total sectors
bytes	per sector
Set	total sectors from CHS
sub_11E4	-- Build BBS device type ID
Parses	device path media type string and generates BBS device type ID
for	the IPLDT / BBS table.
offset	+2 from device path
Default	type for unrecognized devices
Validate	device path node type
if	*((UINT8* )((UINTN)DevicePath + 2) != 0x30) { // MESSAGING_DEVICE_PATH**
length	too small
no	media type
Compare	media type strings
ATAPI	*if (AsciiStrnCmp ((CHAR8 )MediaType, MEDIA_ATAPI, 5) == 0) {**
ATA	master
ATA	(same as ATAPI)
SCSI	*if (AsciiStrnCmp ((CHAR8 )MediaType, MEDIA_SCSI, 4) != 0) {**
USB	*if (AsciiStrnCmp ((CHAR8 )MediaType, MEDIA_USB, 3) != 0) {**
1394	*if (AsciiStrnCmp ((CHAR8 )MediaType, MEDIA_1394, 4) != 0) {**
FIBRE	*if (AsciiStrnCmp ((CHAR8 )MediaType, MEDIA_FIBRE, 5) != 0) {**
FIBRE	(UINT64 )&TypeFields[4] = (UINT64 )((UINTN)DevicePath + 88);
USB	*TypeFields[0] = (UINT8* )((UINTN)DevicePath + 96);**
SCSI	(UINT32 )&TypeFields[0] = (UINT32 )((UINTN)DevicePath + 88);
default	GUID-like type

Generated by HR650X BIOS Decompilation Project