Date: Thu, 30 Mar 2006 18:40:21 GMT From: "Devon H. O'Dell" <devon.odell@gmail.com> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/94939: [acpi] [patch] reboot(8) fails on IBM / Intel blades Message-ID: <200603301840.k2UIeLGE082969@freefall.freebsd.org>
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The following reply was made to PR kern/94939; it has been noted by GNATS. From: "Devon H. O'Dell" <devon.odell@gmail.com> To: "Nate Lawson" <nate@root.org>, "John Baldwin" <jhb@freebsd.org>, bug-followup@freebsd.org Cc: Subject: Re: kern/94939: [acpi] [patch] reboot(8) fails on IBM / Intel blades Date: Thu, 30 Mar 2006 10:31:05 -0800 >John Baldwin wrote: >> On Tuesday 28 March 2006 02:22 pm, Devon H. O'Dell wrote: >>> On Tue, Mar 28, 2006 at 11:08:02AM -0800, Nate Lawson wrote: >>>> The system must reset immediately following the write to this register= . >>>> OSPM assumes that the processor will not execute beyond the write >>>> instruction. OSPM should execute spin loops on the CPUs in the system >>>> following a write to this register. >>> My interpretation of this is ``don't do anything else after >>> the write to the register, because you can't expect to do >>> it.'' Since they say that the system ``must reset immediately >>> following the write'', it seems that this is implemented in >>> hardware, and we can't assume that we will be able to do >>> anything afterwards, anyway. >>> >>>> So I'm ok with the patch being committed if no other tasks need to >>>> happen after this shutdown handler is called. Also, all APs should be >>>> stopped before this happens and it should only occur once on the BSP. >>> I was curious if anything happens after this handler is >>> called -- if there is, we definitely need to move it back >>> to later in the process. Again, I put the code here because it >>> looked to me like the procedure already assumed nothing else >>> is happening, but it sounds like there are other procedures >>> that are in the call queue after this one. >> >> It really should be much later I think: in cpu_reset_real() as that >> is the only place that you know that the APs are stopped. > > I'm not near a BSD box today. Is there a simple, MI way of hooking > there that doesn't require ACPI compiled into the kernel? If it's a > simple matter of moving it to a different shutdown handler or adding a > way for acpi to conditionally override cpu_reset_real, that's ok with > me. I don't want acpi being partially merged into the main kernel. I can move this to its own event handler that will be executed later on. > -- > Nate
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