Date: Thu, 30 Mar 2006 18:30:22 GMT From: Nate Lawson <nate@root.org> To: freebsd-bugs@FreeBSD.org Subject: Re: kern/94939: [acpi] [patch] reboot(8) fails on IBM / Intel blades Message-ID: <200603301830.k2UIUMVa081782@freefall.freebsd.org>
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The following reply was made to PR kern/94939; it has been noted by GNATS. From: Nate Lawson <nate@root.org> To: John Baldwin <jhb@freebsd.org> Cc: "Devon H. O'Dell" <dodell@ixsystems.com>, bug-followup@freebsd.org Subject: Re: kern/94939: [acpi] [patch] reboot(8) fails on IBM / Intel blades Date: Thu, 30 Mar 2006 10:23:42 -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. -- Nate
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