Hi Ben, On Thu, 5 Jun 2008 18:05:56 +0100, Ben Hutchings wrote: > Jean Delvare wrote: > > It really depends on the board. A few boards initialize the limits > > properly, but in general the user really wants to set them, or he/she > > gets either spurious alarms or no alarms at all. > > I have a hard time believing this because in my experience PCs normally > shut down in case of an over-temperature alarm. Have you experienced this often? It never happened to me personally but my understanding is that the CPU will protect itself according to hard-coded limits (unrelated to whatever hardware monitoring drivers can be in used). On some systems ACPI or other BIOS code may write a high CPU temperature limit to the hardware monitoring chip and expect an interrupt if it is crossed (and will act upon it) but for the vast majority of PC motherboards I've seen so far, nothing is done. Limits of the hardware monitoring chips are either disabled or random, and nothing happens when they are crossed (meaning that the user can set them for fun but it's not really needed.) And the few motherboards those BIOS sets a limit, set the CPU temperature limit and that's about it. No voltage limits, no fan limits, and usually no care for system temperature either. I'm not saying that this shouldn't be done - I would love seeing BIOS fully initializing the hardware monitoring chip. But that's not what I have seen in the real world so far. > > Why? In general, the limits and the alarms are informative only, and > > nothing bad will happen if the limits aren't set immediately. So, > > user-space has all the time to set the limits after the driver has been > > loaded. All that matters is that the limits are set before the user > > gets a chance to look at them. > > The way this is supposed to work is that in case of a fault the hardware > is shut down to prevent (further) damage. For a PC motherboard the BIOS > (possibly cooperating with the OS through ACPI) will do that. In the case > of our reference boards, we depend on either hard-wiring (SFE4001) or the > driver (all others) to do this. Can you describe the "hard wiring" in question? Does it mean that the network adapter has the power to abruptly shut down the machine if any limit is crossed? Meaning that the user could shut down the machine just by playing with the limits? Please also describe the software alternative. How do you plan to implement this? I guess we want the user to be able to configure what to do when a limit is crossed (depending on the event), much like we do when a laptop or UPS gets low on battery. And if this is a pure software implementation, then I guess it would make sense to make it generic for all hardware monitoring chips, rather than specific to your network adapter. If something of that kind does not already exist, that is. As a side note, I have to admit that I am very surprised to see that level of hardware monitoring on network adapters. This seems redundant with what the motherboard already offers, in particular for voltages (you get them from the motherboard so they might as well be monitored there.) I would understand a simple temperature sensor as some graphics adapters do, but a full-featured hardware monitoring chip sounds overkill. > > You could make the configuration files available for download from your > > web site directly (it really makes no sense to put these in RPMs), or > > just ask for a wiki account on lm-sensors.org and upload them there. > > I was assuming - not having looked - that we could install a configuration > fragment into a directory which would then be included. Now I see there > is no support for that, either in the lm_sensors release nor Red Hat's > packaging of it. This is work in progress for a year now: http://www.lm-sensors.org/ticket/2174 But apparently Mark is too busy with real life to complete it. If more daughter boards start including hardware monitoring chips, I agree that this will become more needed. > Also I see no provision for hotplug - so if a NIC is hot- > swapped the new NIC won't have its limits initialised. Good point. Hot-plugging of motherboard hardware monitoring chips has never been an issue, obviously... But limits initialization is just one of the problems here. libsensors scans for available hardware monitoring chips at initialization time and will not be happy if a chip goes away or is replaced with a different one. This didn't seem worth working on so far, but maybe we'll have to look into it now. -- Jean Delvare
