Re: Fatal trap 12: page fault on Acer Chromebook 720 (peppy)

From: Michael Gmelin <freebsd_at_grem.de>
Date: Fri, 17 Aug 2018 14:19:52 +0200
> On 17. Aug 2018, at 12:13, Konstantin Belousov <kostikbel_at_gmail.com> wrote:
> 
>> On Fri, Aug 17, 2018 at 10:02:08AM +0100, John Baldwin wrote:
>>> On 8/17/18 9:54 AM, Michael Gmelin wrote:
>>> 
>>> 
>>>>> On 17. Aug 2018, at 08:17, John Baldwin <jhb_at_FreeBSD.org> wrote:
>>>>> 
>>>>> On 8/16/18 1:58 PM, Michael Gmelin wrote:
>>>>> 
>>>>> 
>>>>>>> On 15. Aug 2018, at 15:55, Konstantin Belousov <kostikbel_at_gmail.com <mailto:kostikbel_at_gmail.com>> wrote:
>>>>>>> 
>>>>>>> On Wed, Aug 15, 2018 at 03:52:37PM +0200, Michael Gmelin wrote:
>>>>>>> 
>>>>>>> 
>>>>>>>>> On 15. Aug 2018, at 15:04, Konstantin Belousov <kostikbel_at_gmail.com <mailto:kostikbel_at_gmail.com>> wrote:
>>>>>>>>> 
>>>>>>>>> On Wed, Aug 15, 2018 at 12:51:06AM +0200, Michael Gmelin wrote:
>>>>>>>>> Reviving this old thread, since I just updated to r337818 and a similar
>>>>>>>>> problem is happening again. Since the fix in r334799 (review
>>>>>>>>> https://reviews.freebsd.org/D15675) (mp_)machdep.c have been touched,
>>>>>>>>> so maybe this is related
>>>>>>>>> (https://svnweb.freebsd.org/base?view=revision&revision=334799).
>>>>>>>>> 
>>>>>>>>> Please see the screenshot of the panic below:
>>>>>>>>> https://gist.github.com/grembo/78d0f2a100dd4f16775b85a118769658
>>>>>>>>> 
>>>>>>>>> This is me not digging any deeper, hoping that this is something
>>>>>>>>> obvious. Please let me know if you need more input.
>>>>>>>> 
>>>>>>>> I do not see how recent mp_machdep.c changes could affect this.
>>>>>>>> Can you try newest kernel but old loader ?
>>>>>>> 
>>>>>>> I will try (but that will take a while). Oh, also, it still boots in save mode/with smp disabled.
>>>>>> 
>>>>>> Right, this is because the access to that address through DMAP is only
>>>>>> needed when configuring AP startup resources.
>>>>>> 
>>>>>> Also, I think it is safe to suggest that the bisect is needed.
>>>>> 
>>>>> Using an older loader didn???t help, but I identified the problem:
>>>>> 
>>>>> https://svnweb.freebsd.org/base?view=revision&revision=334952
>>>>> 
>>>>> modified the code you introduced in
>>>>> 
>>>>> https://svnweb.freebsd.org/base?view=revision&revision=334799
>>>>> 
>>>>> By correcting units to pages it also broke booting the Chromebook as a side effect - so the previous fix just worked due to a bug it seems.
>>>>> 
>>>>> Is there an easy way to output the content of physmap at that point (debug.late_console=0 doesn???t work) - like an existing buffer I could use, or would this be more elaborate (I did something complicated last time but didn???t save it, so any simple solution would be preferred).
>>>> 
>>>> How about reverting the commit for now so you get a working console
>>>> and print out the physmap array values along with Maxmem later in
>>>> the boot (or just use kgdb to examine them once the system is running)?
>>>> 
>>> 
>>> This is before the system has a working console (part of calling getmem...), disabling late console makes it hang, physmap changes afterwards, so running kgdb later doesn???t help. Last time I kept a copy of physmap and logged it later to know the original content. I can do that again, I just thought maybe there is a simple mechanism I???m not aware of that would save me some time.
>> 
>> I thought we only modified phys_avail[], but saving a copy of physmap[] and
>> dumping it from kgdb is probably the simplest thing to do.
> UP boot works ?
> 

Well, I can boot if I remove atop(...) (reverting the patch). If this is what you mean.
Received on Fri Aug 17 2018 - 10:19:56 UTC

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