On Thu, Feb 20, 2014 at 11:09:42PM +0000, Matthew Garrett wrote: > On Thu, 2014-02-20 at 16:45 -0600, Russ Anderson wrote: > > On Thu, Feb 20, 2014 at 10:26:45PM +0000, Matthew Garrett wrote: > > > > Because I'm trying to ensure that the default behaviour of the kernel is > > > to *work*. Defaulting to having IPMI be modular means that the default > > > behaviour of the kernel, as far as the ACPI spec goes, is to be broken. > > > > The ACPI spec requires IPMI functionality before a module loads at > > boot time? And the kernel is *broken* if it does not support ACIP IPMI > > functionality before module load time? Really? > > There's no mechanism to ensure that IPMI support will be loaded before > ACPI calls attempt to access IPMI operation regions. Really. And no mechanism can be added to ensure that ACPI call are not attempted before IPMI is initialized? A flag or lock or exported symbol indicating IPMI support is ready. > > > ACPI 4.0 includes support for IPMI operation regions. Modular IPMI means > > > that the kernel will spend a significant amount of time (potentially > > > until a user manually loads a driver) failing to implement part of the > > > IPMI specification. That's a problem, and the correct fix is to ensure > > > that the kernel always implements IPMI support. > > > > The ACPI spec says ipmi_si cannot be a driver? Really? > > What is the real problem you are trying to solve? > > The most straightforward case is that of an ACPI power meter. So it is just a matter of making sure ipmi_si modules loads before the ACPI power meter module loads, right? module dependency issue. > Several > vendors implement this with an IPMI operation region. Calling any of the > power meter functions will trigger access to that IPMI operation region, > which will fail. This may result in driver initialisation failing. There > is no express dependency between the power meter driver and ipmi_si, > because the spec envisages IPMI support as basic kernel functionality. > It's meant to be there before you start loading any other drivers. The spec "envisages"? I get there is a dependency, that IPMI driver needs to be loaded before ACIP power meter. This isn't the first case of a driver being dependent on another driver. That doesn't mean IPMI driver must be built into the kernel. > > > Now, you've described some other problems. I don't disagree that those > > > are problems. The correct thing for us to do with those problems is to > > > fix them, not to simply change the kernel defaults such that it's > > > possible for users to choose between two differently broken states. I'm > > > absolutely willing to help, as long as you're willing to put some > > > reasonable amount of effort into describing them. > > > > How about ACPI IPMI functionality starts when the ipmi_si > > module loads at boot time. > > I've repeatedly asked for you to provide detailed descriptions of the > problems you've seen because I have a genuine interest in fixing them. > If you're just going to childishly refuse then this discussion is > pointless. The distro cases I would point you at are marked private. And you do not have access to our internal support system. A simple google search for "kipmi0" shows a lot of reports of high cpu utilization. And I'm old enough to appreciate being called childishly. :-) -- Russ Anderson, Kernel and Performance Software Team Manager SGI - Silicon Graphics Inc rja@xxxxxxx -- 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
