Description
Hi,
I tried to use snagboot to download a HABv4 signed image to a HAB_CLOSED i.MX6UL, but was immediately told that the device was closed, and snagrecover refused to proceed. From imx_sdp.py:
def check_hab(self):
hab_status = self.dev.read(64, timeout=5)
if hab_status[:4] != __class__.hab_codes["HAB_OPEN"]:
raise ValueError(f"Error: status HAB_CLOSED or unknown: 0x{hab_status.hex()} found on address ")
return None
def read32(self, addr: int) -> int:
self.clear()
self.cmd = __class__.command_codes["READ_REGISTER"]
self.format = __class__.format_codes["FORMAT_32"]
self.addr = addr
self.data_count = 4
packet = self.build_packet()
logger.debug(f"Sending SDP packet {packet}")
self.dev.write(packet)
self.check_hab()
value = self.dev.read(64, timeout=5)[:4]
return int.from_bytes(value, "little")
Reading any register does a self.check_hab() call, which bails if the device is closed. This makes sending a signed image to a closed device impossible, even if the image could actually run.
Would it make more sense to check the image being downloaded first if it is signed/packaged appropriately, and then only bail on closed devices if the image is not signed? And possibly check the result of any HABv4 verifications after the download, before trying to execute the image?
P.S. I changed the exception message to print the hab_status as hex rather than bytes, because (0x12, 0x34, 0x34, 0x12) is confusingly printed as b'\x1244\x12'. Might be a useful change for others.