The MBR contains the partition table, which is always located on the first sector (LBA0) with a memory size
of 512 bytes. The MBR consists of executable code, four partition entries, and the MBR signature. A MBR
can be created by specific tools like the FDISK program.
Table A–5 lists the MBR structure.
Table A-5: MBR Structure
Description
Size (Byte)
Offset
Code area
446
0x000
Partition entry for partition 1
16
0x1BE
Partition entry for partition 2
16
0x1CE
Partition entry for partition 3
16
0x1DE
Partition entry for partition 4
16
0x1EE
MBR signature: 0xAA55
2
0x1FE
The standard MBR structure contains a partition with four 16-bytes entries. Thus, memory cards using this
standard table cannot have more than four primary partitions or up to three primary partitions and one
extended partition.
Each partition type is defined by the partition entry. The boot images are stored in a primary partition with
custom partition type (0xA2). The SD/MMC flash driver does not support a file system, so the boot images
are located in partition A2 at fixed locations.
Table A-6: Partition Entry
Description
Size (Byte)
Offset
Boot indicator. 0x80 indicates that
is it bootable.
1
0x0
Starting CHS value
3
0x1
Partition type
1
0x4
Ending CHS value
3
0x5
LBA of first section in partition
4
0x8
Number of sectors in partition
4
0xB
The boot ROM code configures the SD/MMC controller to default settings for the supported SD/MMC flash
memory.
Altera Corporation
Booting and Configuration Introduction
A-17
SD/MMC Flash Devices
cv_5400a
2013.12.30