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labgrid-project / labgrid

Embedded systems control library for development, testing and installation
https://labgrid.readthedocs.io/
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SerialDriver driver activates U-boot prompt. #176

Closed kjeldflarup closed 6 years ago

kjeldflarup commented 6 years ago

Sometimes the SerialDriver stops u-boot. It seems to press the anykey, and gets the u-boot prompt. Looking in _await_login this comment "# TODO use step timeouts" indicates that this is a known problem.

The interruption of u-boot is caused by _await_login calling self.console.sendline("") as the first thing.
It is of course target dependent, but my board always prints login:, no need to send a newline to get it. Should the target already have passed that point, then say 500 ms silence would indicate that I need to send a newline, to get the current prompt, whether it would be the logged in prompt, the login prompt OR a u-boot prompt.

Thus _await_login should loop on self.console.expect and only send a newline when receiving a timeout and the serial port has been quiet during that period. I had this behavior implemented in the Ruby code which I used before starting to use labgrid.

Furthermore it should be able to detect the U-boot prompt, and recover from that too. But if the interruption can be prevented, this is not necessary.

jluebbe commented 6 years ago

This behavior is in ShellDriver, not in SerialDriver. It's there to trigger printing the current prompt, so that it can continue without waiting. To avoid activating the ShellDriver on a U-Boot prompt, the robust way is to use the UBootDriver and a strategy to explicitly capture the board in U-Boot and then trigger the kernel boot.

kjeldflarup commented 6 years ago

Explicit capture of UBoot, would mean that the test of UBoot is not complete. We might oversee a misconfiguration in Uboot.

jluebbe commented 6 years ago

This should be fixed via PR #193.