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I checked what OpenRM does and it doesn't appear to wrap. Actually `tmrSetCurrentTime_GH100` has the following line: NV_ASSERT_OR_RETURN(secTimerNs < osTimeNs, NV_ERR_INVALID_STATE); meaning it expects the OS/GPU time delta to be positive. The error it returns in that case is ignored by the caller, so nothing gets programmed. In the absence of a better alternative I guess we should do the same thing, i.e. the `checked_sub` and return early (but the returned error should be just logged and ignored). Nouveau AFAICT does not write `NV_PGC6_SCI_SYS_TIMER_OFFSET_*` at all.