In exclusive topology the virtual display is the ONLY monitor on the desktop,
so monitor-control software (the Twinkle Tray / PowerToys PowerDisplay /
Monitorian class) aims its entire DDC traffic — brightness polls,
capabilities-string requests — at OUR monitor. There is no bus and no sink;
the only wrong answer is a slow one (a timeout-shaped failure occupies
win32k's physical-monitor path, serialized per monitor, for its full
duration). Register EvtIddCxMonitorI2CTransmit/Receive and answer every probe
with an immediate STATUS_NOT_SUPPORTED, making the virtual monitor the
cheapest thing on the "bus" to poll. (The receive DDI has no out-arg at the
callback — refusing synchronously refuses the whole transaction.) EDID needs
no equivalent: the OS serves descriptor queries from the blob supplied at
monitor creation without calling the driver.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
enricobuehlerandClaude Fable 5
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