Re: [PATCH v20210111 08/39] xl: fix description of migrate --debug

[Olaf Hering <olaf@xxxxxxxxx>]

Am Mon, 8 Feb 2021 16:39:01 +0000
schrieb Andrew Cooper <andrew.cooper3@xxxxxxxxxx>:

> It is possibly worth noting that you typically do see changed data when
> using --debug, because of how the front/back pairs work.  This was a bit
> of a curveball during development.

I just noticed "migrate --debug" is a noop, "verify" works just for remus or 
colo, per send_domain_memory_live():
- libxl_domain_remus_start sets checkpointed_stream to COLO/REMUS
- libxl_domain_suspend sets checkpointed_stream to NONE.
- external callers can not influence this internal state.
- main_migrate_receive sets it based on the command line option.


In case we want a "verify" functionality also for migration, the "stream_type" 
check could be removed to make it work everywhere.
The domU is suspended, it should not make much difference how often its memory 
is passed around in this suspended state.
But this would be a separate thing to explore.

Having a "LIBXL_SUSPEND_DEBUG/XCFLAGS_DEBUG" might be useful, but in its 
current state the flags should have "STREAM_VERIFY" in their name.

So instead of changing the help string I suggest to remove "--debug" altogether 
from the xl UI.


Olaf

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