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Date:      Wed, 12 Jun 2013 20:30:58 -0700
From:      Justin Hibbits <jhibbits@freebsd.org>
To:        Nathan Whitehorn <nwhitehorn@freebsd.org>
Cc:        FreeBSD PowerPC ML <freebsd-ppc@freebsd.org>
Subject:   Re: Strange panic on ppc64
Message-ID:  <CAHSQbTB6bXpqFM5n8FMmpbbfKik0szDvp9M6KfCWreXKHTaR1g@mail.gmail.com>
In-Reply-To: <CAHSQbTCposTE1AwHS0Ov=FT4w8gNkgpE4x_7-cHhyzMDfZr5UA@mail.gmail.com>
References:  <CAHSQbTAZTc9puGaH0rbhyY11s0%2BL0xGjSabK1kj65UMm1t7j3w@mail.gmail.com> <51AF6661.3060007@freebsd.org> <CAHSQbTBjza0u7nZf4z%2BxpTCcWj-TW-ZigV2-CZexuBOYQX5=3A@mail.gmail.com> <CAHSQbTCvFXDZPsOnmogc0FkZeMXwOP6h40F2kFUu2s6UmffyPw@mail.gmail.com> <51B345BE.5030905@freebsd.org> <CAHSQbTDnwne3KJWN7xjcUw4PhF-uiD4B-4y1Lf90Bfou-2Ppvw@mail.gmail.com> <51B4A389.4020607@freebsd.org> <CAHSQbTACtejaRKiG4qScSV_EdTC8y_k5Qghx_FYebWzstBP61g@mail.gmail.com> <51B5D28C.505@freebsd.org> <51B5D539.8050102@freebsd.org> <CAHSQbTCposTE1AwHS0Ov=FT4w8gNkgpE4x_7-cHhyzMDfZr5UA@mail.gmail.com>

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On Mon, Jun 10, 2013 at 9:20 PM, Justin Hibbits <jhibbits@freebsd.org>wrote:

> On Mon, Jun 10, 2013 at 6:31 AM, Nathan Whitehorn <nwhitehorn@freebsd.org>wrote:
>
>> On 06/10/13 08:20, Nathan Whitehorn wrote:
>> > This is now getting interesting. Reading the tea leaves, what has
>> > happened is that the kernel has called into Open Firmware. Open Firmware
>> > has then crashed early on, before setting up its own trap handlers,
>> > which has then flung you back into FreeBSD's handlers with a totally
>> > bogus environment, causing a second panic, which then causes a *third*
>> > panic when trying to acquire a lock. It would be interesting to know
>> > what the OF environment looked like and what commands it was trying to
>> > execute (in r3), but that may be tricky to get...
>> > -Nathan
>> > _______________________________________________
>>
>> One other point: you can trace this pretty easily by just putting
>> something like:
>>
>> if (pmap_bootstrapped) printf("Open Firmware call %p\n", args);
>>
>> in the top of openfirmware(). If I understood the debugger output
>> correctly, something should be making a firmware call immediately before
>> the crash.
>>
>> As a random guess about what is happening, it is possible OF is trying
>> to allocate memory for itself. We just ignore the possibility that it
>> might want to do that at present, but that is not necessarily a good
>> assumption.
>> -Nathan
>>
>
> I added that, both on entry and exit.  I also have it printing out the
> name of the ofw call, since the first item is always a pointer to the
> name.  I'll be able to report more tomorrow.
>
> - Justin
>

Since putting those printf()s in, my machine's been up for close to 48
hours without a hitch, and I've done a buildworld, plus a whole package
repo rebuild for my G4 (900 packages), 4 concurrent jobs (load average
regularly over 6).  I did see a ton of OF getprop calls for the first 12
hours of being up, but none since.

I'll try some multiple concurrent buildworlds after poudriere finishes.
This is very odd.

- Justin



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