The VS_WRITE_AND_EXECUTE message is now the only way to write runtime parameters and firmware into volatile memory. The legacy VS_RD_MEM, VS_WR_MEM and VS_ST_MAC are deprecated and will no longer be supported by the bootloader. This means that some customers must re-write their applications to boot newer powerline devices.
Figure 4.8. Boot from Host (AR6410/AR7420)
AR7420 LOCAL-HOST
[01] | |
[02] |-------- VS_HOST_ACTION.IND ------->| [03]
[05] |<------- VS_HOST_ACTION.RSP --------| [04]
| | [06]
|<---- VS_WRITE_AND_EXECUTE.REQ -----| [07]
[08] |----- VS_WRITE_AND_EXECUTE.CNF ---->|
|<-----------------------------------| [09]
[10] |----------------------------------->| [11]
[12] | |
[13] |-------- VS_HOST_ACTION.IND ------->| [14]
[16] |<------- VS_HOST_ACTION.RSP --------| [15]
| | [16]
|<-VS_WRITE_AND_EXECUTE_APPLET.REQ --| [17]
[18] |--VS_WRITE_AND_EXECUTE_APPLET.CNF ->|
|<-----------------------------------| [19]
[20] |----------------------------------->|
|<-VS_WRITE_AND_EXECUTE_APPLET.REQ --| [21]
[22] |--VS_WRITE_AND_EXECUTE_APPLET.CNF ->|
|<-----------------------------------| [23]
[24] |----------------------------------->|
[25] | |
The bootloader enters boot-from-host mode based on the hardware strapping or failure to load runtime firmware from flash memory. The device hardware address is 00:B0:52:00:00:01 in this state.
The bootloader broadcasts a VS_HOST_ACTION.IND message with HOST_ACTION_REQ set to 4 to indicate that it is waiting to be configured. The bootloader will continue to broadcast the VS_HOST_ACTION.IND message every 750ms until it receives a VS_HOST_ACTION.RSP message from the local host. The BootROM does not know the local host hardware address at this stage so indications are broadcast, not addressed.
The local host receives a VS_HOST_ACTION.IND message and inspects HOST_ACTION_REQ field to determine the required action. The local host must be programmed to listen and act appropriately. The first indcation requests device configuration.
The local host sends a VS_HOST_ACTION.RSP message with MSTATUS set to 0 to indicate a willingness and ability to service the request.
The bootloader receives the VS_HOST_ACTION.RSP message, stops broadcasting VS_HOST_ACTION.IND messages and waits indefinitely for the local host to act.
The local host retrieves the firmware chain and extracts the configuration applet image from the chain. The firmware chain may be stored on disk or in memory depending on how the local host is programmed.
The local host sends a VS_WRITE_AND_EXECUTE.REQ message with FLAGS set to 2, ALLOWED_MEM_TYPES to 1, CURR_PART_OFFSET to the applet image header IMAGEADDRESS and CURR_PART_LENGTH to the applet image header IMAGELENGTH to download the applet in absolute address mode. Alternately, setting FLAGS to 0 and CURR_PART_OFFSET to 0 will download the applet in relative address mode.
The bootloader acknowledges each VS_WRITE_AND_EXECUTE.REQ message with a VS_WRITE_AND_EXECUTE.CNF message having MSTATUS set to 0.
The local host continues to download the configuration applet in 1400 byte blocks until the last block is reached. The local host sets START_ADDR to the applet image header ENTRYPOINT, CHECKSUM to the applet image header IMAGECHECKSUM and the execute bit in FLAGS to 1.
The bootloader receives the last VS_WRITE_AND_EXECUTE.REQ message, confirms the configuration applet checksum then acknowledges with a VS_WRITE_AND_EXECUTE.CNF message having MSTATUS set to 0.
The local host exists the boot from host sequence and returns to listening mode.
The bootloader executes the configuration applet. The device hardware address is 00:B0:52:00:00:01 in this state.
The bootloader broadcasts a VS_HOST_ACTION.IND message with HOST_ACTION_REQ set to 0 to indicate that it is waiting for runtime parameters and firmware.
The local host receives a VS_HOST_ACTION.IND message and inspects the HOST_ACTION_REQ field to determine the required action. The local host must be programmed to listen and act appropriately.
The bootloader receives the VS_HOST_ACTION.RSP message, stops broadcasting VS_HOST_ACTION.IND messages and waits indefinitely for the local host to act.
The local host locates the parameter chain and firmware chain. The chains may be stored on disk or in memory depending on how the local host is programmed.
The local host sends a VS_WRITE_AND_EXECUTE.REQ message with FLAGS set to 2, ALLOWED_MEM_TYPES set to 1, CURR_PART_OFFSET to the parameter image header IMAGEADDRESS and CURR_PART_LENGTH to the entire parameter image chain length to download parameters in absolute address mode. Alternately, setting FLAGS to 0 and CURR_PART_OFFSET to 0 will download parameters in relative address mode.
The bootloader acknowledges each VS_WRITE_AND_EXECUTE.REQ message with a VS_WRITE_AND_EXECUTE.CNF message having MSTATUS set to 0.
The local host continues to download the parameter chain in 1400 byte blocks until the last block is reached. The local host then sets the START_ADDR field to the parameter image header ENTRYPOINT, CHECKSUM to the parameter image header IMAGECHECKSUM and the execute bit in FLAGS to 1.
The bootloader receives the last VS_WRITE_AND_EXECUTE.REQ message, confirms the parameter chain checksum and acknowledges with a VS_WRITE_AND_EXECUTE.CNF message having MSTATUS set to 0.
The local host sends a VS_WRITE_AND_EXECUTE.REQ message with FLAGS set to 2, ALLOWED_MEM_TYPES to 1, CURR_PART_OFFSET to the firmware image header IMAGEADDRESS and CURR_PART_LENGTH to the firmware image header IMAGELENGTH to download firmware in absolute address mode. Alternately, setting FLAGS to 0 and CURR_PART_OFFSET to 0 will download firmware in relative address mode.
The bootloader acknowledges each VS_WRITE_AND_EXECUTE.REQ message with a VS_WRITE_AND_EXECUTE.CNF message having the MSTATUS field set to 0.
The local host continues to download the parameter chain in 1400 byte blocks until the last block is reached. The local host then sets START_ADDR to the parameter image header ENTRYPOINT, CHECKSUM to the parameter image header IMAGECHECKSUM and the execute bit in FLAGS to 1.
The bootloader receives the last VS_WRITE_AND_EXECUTE.REQ message, confirms the firmware chain checksum and acknowledges with a VS_WRITE_AND_EXECUTE.CNF message having the MSTATUS field set to 0.
The bootloader executes the runtime firmware and the device begins operation. The device hardware address will become that programmed into the parameter inforamtion block.
At this point, runtime firmware is executing in volatile memory with runtime parameters. If the power is reset at this point then all would be lost. If the device has dedicated flash memory attached then we may want to write runtime parameters and firmware to flash memory so that the device can boot from flash in case of a power failure or reset.