panic: integer divide fault on 6.1

Hi all,

I was contacted by Chris who had the same problem.
Since I didn't follow up on my problem he asked me if it was solved
and indeed it was solved by Søren and the fix has been committed to
CURRENT:
http://lists.freebsd.org/pipermail/cvs-all/2006-September/188353.html

I'm hoping this gets MFC'ed in time for 6.2

My conversation with Søren is bellow:

---------- Forwarded message ----------
From: Joao Barros <joao.barros_at_gmail.com>
Date: Sep 14, 2006 8:04 PM
Subject: Re: Fwd: panic: integer divide fault on 6.1
To: Søren Schmidt <sos_at_deepcore.dk>


On 9/13/06, Joao Barros <joao.barros_at_gmail.com> wrote:
> On 9/13/06, Søren Schmidt <sos_at_deepcore.dk> wrote:
> > Joao Barros wrote:
> > > ---------- Forwarded message ----------
> > > From: Sam Leffler <sam_at_errno.com>
> > > Date: Sep 10, 2006 5:16 PM
> > > Subject: Re: panic: integer divide fault on 6.1
> > > To: Joao Barros <joao.barros_at_gmail.com>
> > > Cc: freebsd-current_at_freebsd.org, freebsd-stable_at_freebsd.org, Kris
> > > Kennaway <kris_at_obsecurity.org>
> > >
> > >
> > > Joao Barros wrote:
> > >> On 9/9/06, Kris Kennaway <kris_at_obsecurity.org> wrote:
> > >>> On Sat, Sep 09, 2006 at 09:02:35PM +0100, Joao Barros wrote:
> > >>> > On 9/9/06, Max Laier <max_at_love2party.net> wrote:
> > >>> > >
> > >>> > >Can you try to get a dump, trace, or at least figure out which
> > >>> function
> > >>> > >the IP is refering to?
> > >>> > >
> > >>> >
> > >>> > Well, the problem only occurs when I boot from the disk and the
> > >>> > installed kernel doesn't have debug support.
> > >>> > Does 'set dumpdev=' work from the boot loader? I tried some
> > >>> > combinations with no success.
> > >>>
> > >>> No.
> > >>>
> > >>> > I can try and install a 6-STABLE snapshot if there's no way of
> > >>> getting
> > >>> > the info needed.
> > >>>
> > >>> You can either try to install a new kernel with DDB support, or follow
> > >>> the "instruction pointer" method in the developers handbook chapter on
> > >>> kernel debugging.
> > >>
> > >> I copied a CURRENT kernel from a 200608 snapshot and the problem also
> > >> occurs thus I'm adding current_at_.
> > >> My current laptop doesn't have a serial port so I'm copying this by
> > >> hand:
> > >>
> > >> Fatal trap 18: integer divide fault while in kernel mode
> > >> cpuid = 0; apic id = 00
> > >> instruction pointer     = 0x20:0xc08a1fb7
> > >> stack pointer           = 0x28:0xc0c20b14
> > >> frame pointer           = 0x28:0xc0c20b9c
> > >> code segment            = base 0x0, limit 0xfffff, type 0x1b
> > >>                       = DPL 0, pres 1, def32 1, gran 1
> > >> processor eflags        = interrupt enabled, resume, IOPL = 0
> > >> current process         = 0 (swapper)
> > >> [thread pid 0 tid 0 ]
> > >> Stopped at    __qdivrem+0x3b: divl    %ecx,%eax
> > >>
> > >> db> bt
> > >> Tracing pid 0 tid0 td 0xc0a0c818
> > >> __qdivrem(37fdfa0,0,0,0,0,...) at __qdivrem+0x3b
> > >> __udivdi3(37fdfa0,0,0,0) at __udivdi3+0x16
> > >> ata_raid_promise_read_meta(c37a5000,c09f4a80,1,8086,c37a5000,...) at
> > >> ata_raid_promise_read_meta+0x9b
> > >> ata_raid_read_metadata(c37a5000,c37a5000,c0c20c70,c06b58a4,c37a5000,...)
> > >> at ata_raid_metadata+0x2be
> > >> ata_raid_subdisk_attach(c37a5000) at ata_raid_subdisk_attach+0x33
> > >> device_attach(c37a5000,c37a5180,c37a5000,c36885c0,0,...) at
> > >> device_attach+0x58
> > >> device_probe_and_attach(c37a5200,c37a5200,c08ec9a9,0,c37a5180,...) at
> > >> bus_generic_attach+0x16
> > >> ad_attach(c37a5200) at ad_attach+0x2c8
> > >> device_attach(c37a5200,c095f2d0,c37a5200,0,c368d800,...) at
> > >> device_attach+0x58
> > >> device_probe_and_attach(c37a5200) at device_probe_and_atach+0xe0
> > >> bus_generic_attach(c3659080,c3659080,ffffffff,0,c37a5200,...) at
> > >> bus_generic_attach+0x16
> > >> ata_identify(c3659080) at ata_identify+0x1c8
> > >> ata_boot_attach(0xc0a11d80,0,c09212e7,47,...) at ata_boot_attach+0x3e
> > >> run_interrupt_drive_config_hooks(0,c1ec00,c1e000,0,c0451065,...) at
> > >> run_interrupt_drive_config_hooks+0x43
> > >> mi_startup() at mi_startup+0x96
> > >> begin() at begin+0x2c
> > >>
> > >> This board has a Promise SATA raid controller and it is disabled in
> > >> the BIOS. I even tried disabling it through a jumper but it still
> > >> stops.
> > >>
> > >
> > > In sys/dev/ata/ata-raid.h the PROMISE_LBA macro does an unchecked
> > > calculation that apparently can divide by zero.  Soren would likely
> > > understand the root cause of this problem but until then you can patch
> > > the driver to workaround the problem.
> > >
> > >        Sam
> > >
> > >
> > > Hi Søren,
> > >
> > > I don't know if you bumped into this thread but this should definitely
> > > be fixed.
> > > Do you want me to open a PR?
> > >
> > Hmm, the problem seems to be that the geometry thats gotten from the
> > disk has (all) zero's in it, which we cannot handle.
> > Its most likely because your BIOS put invalid or no current geometry
> > info in the disks parameters page.
> >
> > If you are up to a little debugging, you could try this patch:
> >
> > diff -u -r1.189.2.4 ata-disk.c
> > --- ata-disk.c  4 Apr 2006 16:07:42 -0000       1.189.2.4
> > +++ ata-disk.c  13 Sep 2006 06:18:59 -0000
> > _at__at_ -97,7 +97,8 _at__at_
> >      }
> >      device_set_ivars(dev, adp);
> >
> > -    if (atadev->param.atavalid & ATA_FLAG_54_58) {
> > +    if ((atadev->param.atavalid & ATA_FLAG_54_58) &&
> > +       atadev->param.current_heads && atadev->param.current_sectors) {
> >         adp->heads = atadev->param.current_heads;
> >         adp->sectors = atadev->param.current_sectors;
> >         adp->total_secs = (u_int32_t)atadev->param.current_size_1 |
> >
> >
> > -Søren
> >
>
> Sure, I'll test it when I get home later today and start building a
> kernel on another machine that's currently off.
> I'll give you feedback tomorrow.
> Thanks,
>
> --
> Joao Barros
>

I'm happy to report that your patch did the trick. The machine happily
boot a today's CURRENT+patch :)
Tell me if you need to test something more.
Thanks!

--
Joao Barros