Hi all, I am struggling with a S4 issue. On a Napa dual-core laptop, sometimes when resuming from S4, kernel panic occurs, then system reboots. After some investigation, I found it's due to CPU1(AP) can't be woken up in time, and this can be alleviated, even eliminated by introducing more delay in function wakeup_secondary_cpu().In official kernel tree, there were three lines in this function for delaying: mdelay(10), udelay(300) and udelay(200), now I changed them all to mdelay(500). Seems incorrect timing has led to the issue. Could you help me to root cause it? Thanks. Best regards Hu, Fenghua - To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html