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Date:      Fri, 17 Aug 2018 14:19:52 +0200
From:      Michael Gmelin <freebsd@grem.de>
To:        Konstantin Belousov <kostikbel@gmail.com>
Cc:        John Baldwin <jhb@FreeBSD.org>, "freebsd-current@freebsd.org" <freebsd-current@freebsd.org>, Matthias Apitz <guru@unixarea.de>
Subject:   Re: Fatal trap 12: page fault on Acer Chromebook 720 (peppy)
Message-ID:  <04B03A28-B894-46A6-B75D-C05B55234245@grem.de>
In-Reply-To: <20180817101306.GG2340@kib.kiev.ua>
References:  <20180605131135.GH2450@kib.kiev.ua> <20180606010625.62632920@bsd64.grem.de> <20180815005106.69402d23@bsd64.grem.de> <20180815130447.GZ2340@kib.kiev.ua> <C26CD25D-3CB0-4F7E-8B50-F7E95E16B776@grem.de> <20180815135531.GA2340@kib.kiev.ua> <FAEA5B0A-5302-4A48-B322-21CB0D97C8CC@grem.de> <e82ed552-83b0-5331-3117-6750b8c205f7@FreeBSD.org> <07E28AC5-EBE6-4893-810A-6C03F07925C8@grem.de> <8726bc32-6023-bfe1-7600-5b2c706236f8@FreeBSD.org> <20180817101306.GG2340@kib.kiev.ua>

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> On 17. Aug 2018, at 12:13, Konstantin Belousov <kostikbel@gmail.com> wrote=
:
>=20
>> On Fri, Aug 17, 2018 at 10:02:08AM +0100, John Baldwin wrote:
>>> On 8/17/18 9:54 AM, Michael Gmelin wrote:
>>>=20
>>>=20
>>>>> On 17. Aug 2018, at 08:17, John Baldwin <jhb@FreeBSD.org> wrote:
>>>>>=20
>>>>> On 8/16/18 1:58 PM, Michael Gmelin wrote:
>>>>>=20
>>>>>=20
>>>>>>> On 15. Aug 2018, at 15:55, Konstantin Belousov <kostikbel@gmail.com <=
mailto:kostikbel@gmail.com>> wrote:
>>>>>>>=20
>>>>>>> On Wed, Aug 15, 2018 at 03:52:37PM +0200, Michael Gmelin wrote:
>>>>>>>=20
>>>>>>>=20
>>>>>>>>> On 15. Aug 2018, at 15:04, Konstantin Belousov <kostikbel@gmail.co=
m <mailto:kostikbel@gmail.com>> wrote:
>>>>>>>>>=20
>>>>>>>>> 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 si=
milar
>>>>>>>>> problem is happening again. Since the fix in r334799 (review
>>>>>>>>> https://reviews.freebsd.org/D15675) (mp_)machdep.c have been touch=
ed,
>>>>>>>>> so maybe this is related
>>>>>>>>> (https://svnweb.freebsd.org/base?view=3Drevision&revision=3D334799=
).
>>>>>>>>>=20
>>>>>>>>> Please see the screenshot of the panic below:
>>>>>>>>> https://gist.github.com/grembo/78d0f2a100dd4f16775b85a118769658
>>>>>>>>>=20
>>>>>>>>> This is me not digging any deeper, hoping that this is something
>>>>>>>>> obvious. Please let me know if you need more input.
>>>>>>>>=20
>>>>>>>> I do not see how recent mp_machdep.c changes could affect this.
>>>>>>>> Can you try newest kernel but old loader ?
>>>>>>>=20
>>>>>>> I will try (but that will take a while). Oh, also, it still boots in=
 save mode/with smp disabled.
>>>>>>=20
>>>>>> Right, this is because the access to that address through DMAP is onl=
y
>>>>>> needed when configuring AP startup resources.
>>>>>>=20
>>>>>> Also, I think it is safe to suggest that the bisect is needed.
>>>>>=20
>>>>> Using an older loader didn???t help, but I identified the problem:
>>>>>=20
>>>>> https://svnweb.freebsd.org/base?view=3Drevision&revision=3D334952
>>>>>=20
>>>>> modified the code you introduced in
>>>>>=20
>>>>> https://svnweb.freebsd.org/base?view=3Drevision&revision=3D334799
>>>>>=20
>>>>> 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.
>>>>>=20
>>>>> Is there an easy way to output the content of physmap at that point (d=
ebug.late_console=3D0 doesn???t work) - like an existing buffer I could use,=
 or would this be more elaborate (I did something complicated last time but d=
idn???t save it, so any simple solution would be preferred).
>>>>=20
>>>> 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)?=

>>>>=20
>>>=20
>>> This is before the system has a working console (part of calling getmem.=
..), disabling late console makes it hang, physmap changes afterwards, so ru=
nning kgdb later doesn???t help. Last time I kept a copy of physmap and logg=
ed it later to know the original content. I can do that again, I just though=
t maybe there is a simple mechanism I???m not aware of that would save me so=
me time.
>>=20
>> I thought we only modified phys_avail[], but saving a copy of physmap[] a=
nd
>> dumping it from kgdb is probably the simplest thing to do.
> UP boot works ?
>=20

Well, I can boot if I remove atop(...) (reverting the patch). If this is wha=
t you mean.





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