2 Decode a hard disk partitioned with the legacy MBR found on most PC's
4 MBR - Master Boot Record is in the first sector of a partitioned hard disk.
5 The MBR supports four partitions per disk. The MBR also contains legacy
6 code that is not run on an EFI system. The legacy code reads the
7 first sector of the active partition into memory and
9 BPB - Boot(?) Parameter Block is in the first sector of a FAT file system.
10 The BPB contains information about the FAT file system. The BPB is
11 always on the first sector of a media. The first sector also contains
12 the legacy boot strap code.
14 Copyright (c) 2006 - 2008, Intel Corporation. <BR>
15 All rights reserved. This program and the accompanying materials
16 are licensed and made available under the terms and conditions of the BSD License
17 which accompanies this distribution. The full text of the license may be found at
18 http://opensource.org/licenses/bsd-license.php
20 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
21 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
25 #include "Partition.h"
28 Test to see if the Mbr buffer is a valid MBR.
30 @param Mbr Parent Handle.
31 @param LastLba Last Lba address on the device.
33 @retval TRUE Mbr is a Valid MBR.
34 @retval FALSE Mbr is not a Valid MBR.
39 IN MASTER_BOOT_RECORD
*Mbr
,
50 if (Mbr
->Signature
!= MBR_SIGNATURE
) {
54 // The BPB also has this signature, so it can not be used alone.
57 for (Index1
= 0; Index1
< MAX_MBR_PARTITIONS
; Index1
++) {
58 if (Mbr
->Partition
[Index1
].OSIndicator
== 0x00 || UNPACK_UINT32 (Mbr
->Partition
[Index1
].SizeInLBA
) == 0) {
63 StartingLBA
= UNPACK_UINT32 (Mbr
->Partition
[Index1
].StartingLBA
);
64 EndingLBA
= StartingLBA
+ UNPACK_UINT32 (Mbr
->Partition
[Index1
].SizeInLBA
) - 1;
65 if (EndingLBA
> LastLba
) {
67 // Compatibility Errata:
68 // Some systems try to hide drive space with their INT 13h driver
69 // This does not hide space from the OS driver. This means the MBR
70 // that gets created from DOS is smaller than the MBR created from
71 // a real OS (NT & Win98). This leads to BlockIo->LastBlock being
72 // wrong on some systems FDISKed by the OS.
74 // return FALSE since no block devices on a system are implemented
80 for (Index2
= Index1
+ 1; Index2
< MAX_MBR_PARTITIONS
; Index2
++) {
81 if (Mbr
->Partition
[Index2
].OSIndicator
== 0x00 || UNPACK_UINT32 (Mbr
->Partition
[Index2
].SizeInLBA
) == 0) {
85 NewEndingLBA
= UNPACK_UINT32 (Mbr
->Partition
[Index2
].StartingLBA
) + UNPACK_UINT32 (Mbr
->Partition
[Index2
].SizeInLBA
) - 1;
86 if (NewEndingLBA
>= StartingLBA
&& UNPACK_UINT32 (Mbr
->Partition
[Index2
].StartingLBA
) <= EndingLBA
) {
88 // This region overlaps with the Index1'th region
95 // None of the regions overlapped so MBR is O.K.
102 Install child handles if the Handle supports MBR format.
104 @param This Calling context.
105 @param Handle Parent Handle.
106 @param DiskIo Parent DiskIo interface.
107 @param BlockIo Parent BlockIo interface.
108 @param DevicePath Parent Device Path.
110 @retval EFI_SUCCESS A child handle was added.
111 @retval EFI_MEDIA_CHANGED Media change was detected.
112 @retval Others MBR partition was not found.
116 PartitionInstallMbrChildHandles (
117 IN EFI_DRIVER_BINDING_PROTOCOL
*This
,
118 IN EFI_HANDLE Handle
,
119 IN EFI_DISK_IO_PROTOCOL
*DiskIo
,
120 IN EFI_BLOCK_IO_PROTOCOL
*BlockIo
,
121 IN EFI_DEVICE_PATH_PROTOCOL
*DevicePath
125 MASTER_BOOT_RECORD
*Mbr
;
126 UINT32 ExtMbrStartingLba
;
128 HARDDRIVE_DEVICE_PATH HdDev
;
129 HARDDRIVE_DEVICE_PATH ParentHdDev
;
131 UINT32 PartitionNumber
;
132 EFI_DEVICE_PATH_PROTOCOL
*DevicePathNode
;
133 EFI_DEVICE_PATH_PROTOCOL
*LastDevicePathNode
;
136 Found
= EFI_NOT_FOUND
;
138 Mbr
= AllocatePool (BlockIo
->Media
->BlockSize
);
143 Status
= BlockIo
->ReadBlocks (
145 BlockIo
->Media
->MediaId
,
147 BlockIo
->Media
->BlockSize
,
150 if (EFI_ERROR (Status
)) {
154 if (!PartitionValidMbr (Mbr
, BlockIo
->Media
->LastBlock
)) {
158 // We have a valid mbr - add each partition
161 // Get starting and ending LBA of the parent block device.
163 LastDevicePathNode
= NULL
;
164 ZeroMem (&ParentHdDev
, sizeof (ParentHdDev
));
165 DevicePathNode
= DevicePath
;
166 while (!EfiIsDevicePathEnd (DevicePathNode
)) {
167 LastDevicePathNode
= DevicePathNode
;
168 DevicePathNode
= EfiNextDevicePathNode (DevicePathNode
);
171 if (LastDevicePathNode
!= NULL
) {
172 if (DevicePathType (LastDevicePathNode
) == MEDIA_DEVICE_PATH
&&
173 DevicePathSubType (LastDevicePathNode
) == MEDIA_HARDDRIVE_DP
175 CopyMem (&ParentHdDev
, LastDevicePathNode
, sizeof (ParentHdDev
));
177 LastDevicePathNode
= NULL
;
183 ZeroMem (&HdDev
, sizeof (HdDev
));
184 HdDev
.Header
.Type
= MEDIA_DEVICE_PATH
;
185 HdDev
.Header
.SubType
= MEDIA_HARDDRIVE_DP
;
186 SetDevicePathNodeLength (&HdDev
.Header
, sizeof (HdDev
));
187 HdDev
.MBRType
= MBR_TYPE_PCAT
;
188 HdDev
.SignatureType
= SIGNATURE_TYPE_MBR
;
190 if (LastDevicePathNode
== NULL
) {
192 // This is a MBR, add each partition
194 for (Index
= 0; Index
< MAX_MBR_PARTITIONS
; Index
++) {
195 if (Mbr
->Partition
[Index
].OSIndicator
== 0x00 || UNPACK_UINT32 (Mbr
->Partition
[Index
].SizeInLBA
) == 0) {
197 // Don't use null MBR entries
202 if (Mbr
->Partition
[Index
].OSIndicator
== PMBR_GPT_PARTITION
) {
204 // This is the guard MBR for the GPT. If you ever see a GPT disk with zero partitions you can get here.
205 // We can not produce an MBR BlockIo for this device as the MBR spans the GPT headers. So formating
206 // this BlockIo would corrupt the GPT structures and require a recovery that would corrupt the format
207 // that corrupted the GPT partition.
212 HdDev
.PartitionNumber
= PartitionNumber
++;
213 HdDev
.PartitionStart
= UNPACK_UINT32 (Mbr
->Partition
[Index
].StartingLBA
);
214 HdDev
.PartitionSize
= UNPACK_UINT32 (Mbr
->Partition
[Index
].SizeInLBA
);
215 CopyMem (HdDev
.Signature
, &(Mbr
->UniqueMbrSignature
[0]), sizeof (UINT32
));
217 Status
= PartitionInstallChildHandle (
223 (EFI_DEVICE_PATH_PROTOCOL
*) &HdDev
,
224 HdDev
.PartitionStart
,
225 HdDev
.PartitionStart
+ HdDev
.PartitionSize
- 1,
227 (BOOLEAN
) (Mbr
->Partition
[Index
].OSIndicator
== EFI_PARTITION
)
230 if (!EFI_ERROR (Status
)) {
236 // It's an extended partition. Follow the extended partition
237 // chain to get all the logical drives
239 ExtMbrStartingLba
= 0;
243 Status
= BlockIo
->ReadBlocks (
245 BlockIo
->Media
->MediaId
,
247 BlockIo
->Media
->BlockSize
,
250 if (EFI_ERROR (Status
)) {
255 if (UNPACK_UINT32 (Mbr
->Partition
[0].SizeInLBA
) == 0) {
259 if ((Mbr
->Partition
[0].OSIndicator
== EXTENDED_DOS_PARTITION
) ||
260 (Mbr
->Partition
[0].OSIndicator
== EXTENDED_WINDOWS_PARTITION
)) {
261 ExtMbrStartingLba
= UNPACK_UINT32 (Mbr
->Partition
[0].StartingLBA
);
264 HdDev
.PartitionNumber
= PartitionNumber
++;
265 HdDev
.PartitionStart
= UNPACK_UINT32 (Mbr
->Partition
[0].StartingLBA
) + ExtMbrStartingLba
+ ParentHdDev
.PartitionStart
;
266 HdDev
.PartitionSize
= UNPACK_UINT32 (Mbr
->Partition
[0].SizeInLBA
);
267 if ((HdDev
.PartitionStart
+ HdDev
.PartitionSize
- 1 >= ParentHdDev
.PartitionStart
+ ParentHdDev
.PartitionSize
) ||
268 (HdDev
.PartitionStart
<= ParentHdDev
.PartitionStart
)) {
273 // The signature in EBR(Extended Boot Record) should always be 0.
275 *((UINT32
*) &HdDev
.Signature
[0]) = 0;
277 Status
= PartitionInstallChildHandle (
283 (EFI_DEVICE_PATH_PROTOCOL
*) &HdDev
,
284 HdDev
.PartitionStart
- ParentHdDev
.PartitionStart
,
285 HdDev
.PartitionStart
- ParentHdDev
.PartitionStart
+ HdDev
.PartitionSize
- 1,
287 (BOOLEAN
) (Mbr
->Partition
[0].OSIndicator
== EFI_PARTITION
)
289 if (!EFI_ERROR (Status
)) {
293 if ((Mbr
->Partition
[1].OSIndicator
!= EXTENDED_DOS_PARTITION
) &&
294 (Mbr
->Partition
[1].OSIndicator
!= EXTENDED_WINDOWS_PARTITION
)
299 ExtMbrStartingLba
= UNPACK_UINT32 (Mbr
->Partition
[1].StartingLBA
);
301 // Don't allow partition to be self referencing
303 if (ExtMbrStartingLba
== 0) {
306 } while (ExtMbrStartingLba
< ParentHdDev
.PartitionSize
);