I have been experiencing hard lockups running a real-time application under preempt-rt. Having originally had this problem while running under 2.6.29.4-rt16, today I upgraded to 2.6.31.12-rt21, but the problem persisted. Under both kernels, the computer simply freezes, usually after a few hours of otherwise flawless operation. Nothing appears on the serial console or in the system log when the system freezes. Unfortunately, turning on the NMI watchdog stops the freezes from occurring at all, such that I can't force an Oops that way. I have tried running memtest86 on the RAM, without detecting any memory errors, and I have verified that the same problem occurs on two different (but essentially identical) computers. I wonder whether there might be a clue in the fact that turning on the NMI watchdog stops the freezes from occuring. Turning on the watchdog unfortunately turns off tickless mode, which I need. According to the boot-time messages, tickless is turned off because the local APIC is non-functional (presumably because the NMI watchdog is using it). What kind of bugs would be more likely to be seen when running under tickless? Could anybody give me any ideas on how to further debug this problem? I have been trying to figure this out for weeks, but I haven't found any clues. In case it is important, the CPU is a 1.8GHz Intel Celeron, on a Foxconn motherboard with an Intel G31 chipset, and Intel GMA 3100 onboard graphics. I am running the kernel (downloaded from kernel.org) under Unbuntu 9.10. The computer also hosts two commercial digital I/O boards, both generating interrupts, and one commercial analog I/O board. Thank you, Martin -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
