6.23.3 Boot Parameter Table
The ROM Bootloader (RBL) is guided by the boot parameter table to carry out the boot process. The boot parameter table is the most common format the RBL employs to determine the boot flow. These boot parameter tables have certain parameters common across all the boot modes, while the rest of the parameters are unique to the boot modes. Table 6-73 lists the common entries in the boot parameter table.
Table 6-73 Boot Parameter Table Common Values
Byte Offset |
Name |
Description |
0 |
Length |
The length of this table, including this length field, in bytes. |
2 |
Checksum |
Identifies the device port number to boot from, if applicable. The value 0xFFFF indicates that all ports are configured (Ethernet). |
4 |
Boot Mode |
See Table 6-74 |
6 |
Port Num |
Identifies the device port number to boot from, if applicable. The value 0xFFFF indicates that all ports are configured (Ethernet). |
8 |
PLL config, MSW |
PLL configuration, MSW (see Figure 6-37) |
10 |
PLL config, LSW |
PLL configuration, LSW |
Table 6-74 Boot Parameter Table Boot Mode Field
Value |
Boot Mode |
10 |
Ethernet (boot table) (C6654 only) |
20 |
Rapid I/O |
30 |
PCIe (C6654 only) |
40 |
I2C Master |
41 |
I2C Slave |
42 |
I2C Master Write |
50 |
SPI |
70 |
EMIF16 |
80 |
NAND |
81 |
NAND I2C |
100 |
SLEEP, no PLL configuration |
110 |
UART |
Figure 6-37 Boot Parameter PLL Configuration Field
PLL Config Ctl |
PLL Multiplier |
PLL Predivider |
PLL Post-Divider |
Table 6-75 PLL Configuration Field Description
Field |
Value |
Description |
PLL Config Ctl |
0b00 |
PLL is not configured |
0b01 |
PLL is configured only if it is currently disabled or in bypass |
0b10 |
PLL is configured only if it is currently disabled or in bypass |
0b11 |
PLL is disabled and put into bypass |
Predivider |
0-255 |
Input clock division. The value 0 is treated as predivide by 1 |
Multiplier |
0-16383 |
Multiplier. The value 0 is treated as multiply by 1 |
Post-divider |
0-255 |
PLL output division. The value 0 is treated as post divide by 1 |