kernel: Switch kexec test to select_serial_terminal

[czerw]

Fix poo#97004: Use select_serial_terminal instead of root console to
make test more robust. Test maintainer was updated.

• Related ticket: https://progress.opensuse.org/issues/97004
• Needles: none
• Verification run:
  15-SP4 x86_64: https://openqa.suse.de/tests/6882461
  15-SP4 aarch64: https://openqa.suse.de/tests/6882466
  15-SP4 ppc64le: https://openqa.suse.de/tests/6882467
  15-SP3 x86_64: https://openqa.suse.de/tests/6882463
  15-SP2 x86_64: https://openqa.suse.de/tests/6882480
  15 x86_64: https://openqa.suse.de/tests/6882544
  12-SP5 x86_64: https://openqa.suse.de/tests/6882647
  12-SP4 x86_64: https://openqa.suse.de/t6882548

[czerw]

@mdoucha @pevik please check

[mdoucha]

It looks good but select_serial_terminal() after kexec will only wait 95 seconds for login prompt. Do you think it'll be enough in all cases?

[pevik]

It looks good but select_serial_terminal() after kexec will only wait 95 seconds for login prompt. Do you think it'll be enough in all cases?

Good point, but shouldn't this be handled somewhere in https://github.com/os-autoinst/os-autoinst/blob/master/consoles/serial_screen.pm or https://github.com/os-autoinst/os-autoinst/blob/master/consoles/virtio_terminal.pm (add proper timeout based on backend/arch?)
I suppose one of them handles the timeout. Or is the timeout based on needles setup?

[mdoucha]

This is normally handled by wait_boot() which ensures that the system will be fully booted before calling select_serial_terminal(). But kexec bypasses Grub so $self->wait_boot_past_bootloader() would be the correct method to call here.

[czerw]

Added missing $self->wait_boot_past_bootloader() and updated verifications in description.

[mdoucha]

LGTM