I don't see a difference between the results. Apparently the barrier
option doesn't change a thing.
Ok. I don't like it, but I can see how it's compelling. I'd like to
see the documentation improved though. I also think a warning printed
on stdio about the safety of the option would be appropriate.
I disagree with this last bit.
Errors should be issued if the user did something wrong.
Warnings should be issued if qemu did (or will soon do) something other than
what the user requested, or otherwise made questionable decisions on the
user's behalf.
In this case we're doing exactly what the user requested. The only plausible
failure case is where a user is blindly trying options that they clearly don't
understand or read the documentation for. I have zero sympathy for complaints
like "Someone on the Internet told me to use --breakme, and broke thinks".