sidecar: Clear the response buffer before running - #4071
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Pull request overview
This change fixes a subtle correctness issue in the sidecar VP run path: previously, run() attempted to “clear” the command buffer by writing a () input, but () is zero-sized and therefore doesn’t overwrite any bytes in the shared command page. The update ensures the shared buffer is actually written before starting the VP, preventing stale data from being interpreted as a new RUN_VP result.
Changes:
- Write a 1-byte, harmless value (
RunVpResponse { intercept: 0 }) into the command page before issuingRUN_VP. - Preserve existing
wait()semantics (intercept != 0) while ensuring the output byte is deterministically initialized.
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July 30, 2026 14:57
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Setting this value to
()doesn't actually write anything, as unit is zero sized. Instead, set the value to something sized but harmless, in this case a RunVpResponse indicating a spurious exit with no real intercept.