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Date:      Sun, 6 Jan 2013 04:12:45 +0100
From:      Marius Strobl <marius@alchemy.franken.de>
To:        Kurt Lidl <lidl@pix.net>, mav@freebsd.org, freebsd-sparc64@freebsd.org
Subject:   Re: smartmontools panics 9.1-RELEASE on sunfire 240
Message-ID:  <20130106031245.GC26039@alchemy.franken.de>
In-Reply-To: <20130106021923.GE1410@funkthat.com>
References:  <20130104051914.GA22613@pix.net> <20130104235336.GB37999@alchemy.franken.de> <20130105013224.GA31361@pix.net> <20130105015242.GB26039@alchemy.franken.de> <20130106021923.GE1410@funkthat.com>

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On Sat, Jan 05, 2013 at 06:19:23PM -0800, John-Mark Gurney wrote:
> Marius Strobl wrote this message on Sat, Jan 05, 2013 at 02:52 +0100:
> > On Fri, Jan 04, 2013 at 08:32:24PM -0500, Kurt Lidl wrote:
> > > On Sat, Jan 05, 2013 at 12:53:36AM +0100, Marius Strobl wrote:
> > > > Uhm, probably an userland buffer which isn't even 16-bit aligned.
> > > > If that's the cause, the attached patch hopefully should at least
> > > > prevent the panic. If it does, smartmontools still need to be fixed
> > > > though.
> > > 
> > > You patch prevents the panic from happening.
> > > When I try to start smartd now, it reports:
> > > 
> > > root@host-98: /usr/local/etc/rc.d/smartd onestart
> > > Starting smartd.
> > > smartd: cam_send_ccb: Invalid argument
> > > /usr/local/etc/rc.d/smartd: WARNING: failed to start smartd
> > > 
> > > I had updated the kernel on the machine to 9-STABLE, and
> > > verified that without this patch, the crash still happened with
> > > a 9-STABLE kernel, in addition to 9.1-RELEASE kernel.
> > > 
> > > My kernel now identifies itself as:
> > > FreeBSD 9.1-STABLE (GENERIC) #1 r245044:245048M: Fri Jan  4 20:19:50 EST 2013
> > > 
> > > -Kurt
> > > 
> > > > Index: cam_periph.c
> > > > ===================================================================
> > > > --- cam_periph.c	(revision 245046)
> > > > +++ cam_periph.c	(working copy)
> > > > @@ -744,6 +744,9 @@ cam_periph_mapmem(union ccb *ccb, struct cam_perip
> > > >  		if ((ccb->ccb_h.flags & CAM_DIR_MASK) == CAM_DIR_NONE)
> > > >  			return(0);
> > > >  
> > > > +		if ((uintptr_t)ccb->ataio.data_ptr % sizeof(uint16_t) != 0)
> > > > +			return (EINVAL);
> > > > +
> > > >  		data_ptrs[0] = &ccb->ataio.data_ptr;
> > > >  		lengths[0] = ccb->ataio.dxfer_len;
> > > >  		dirs[0] = ccb->ccb_h.flags & CAM_DIR_MASK;
> > > 
> > 
> > Alexander, are you okay with this approach or do you have a better
> > idea how to handle this? In any case, it doesn't seem to make sense
> > to teach the kernel how to cope with arbitrarily aligned buffers for
> > ATA.
> 
> Shouldn't we make it dependant on the __NO_STRICT_ALIGNMENT define so
> that it won't immediately break other arches?
> 

No, not doing so tremendously helps ensuring that the software is
properly written (apart from compact flash, ATA devices really
only support 16-bit and 32-bit accesses) and judging the history
of the patches in the smartmontools port it apparently already
has to care about proper alignment for SCSI anyway. It would also
not be the first time the smartmontools port is blown out of the
water :)

Marius




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