Re: linux kernel panic when ejecting ieee1394 ipod

[Andrew de Quincey <adq_dvb@lidskialf.net>]

On Thursday 08 December 2005 01:19, Andrew de Quincey wrote:
> On Wednesday 07 December 2005 23:58, Andrew de Quincey wrote:
> > Reposting to the -devel list since there was no response on -user.
> >
> > Hi, I'm using linux kernel 2.6.14 with an generation 1 ipod connected via
> > ieee1394/sbp2.
> >
> > I can mount/unmount it and use it fine. It even works with HAL now.
> >
> > The problem comes when I want to remove it. If I do:
> >
> > eject /dev/sdb
> >
> > The kernel panics with the following error:
> > Kernel panic - not syncing: PCI-DMA: high address but no IOMMU
> >
> > I'm using an nforce 4 motherboard (Asus A8N-SLI Deluxe). The ipod is
> > attached to the ieee1394 port on a creative labs Audigy2 sound card (uses
> > OHCI-1394).
>
> More info (I'm on an AMD64 in 64 bit mode BTW):
>
> eject sends a CDROMEJECT ioctl first of all. It is this IOCTL that kills my
> system. If I hack/tell it to just use a "SCSI eject", it works and actually
> makes my ipod show that tick thing showing it is safe to remove it.

Yet more info:

eject -s sends the following SCSI packet command to the sbp/ipod device:

1b 00 00 00 02 00 with a direction of DMA_NONE

eject -r results in the same via the CDROMEJECT translator in 
scsi_cmd_ioctl(), but with a direction of DMA_TO_DEVICE. Thats what crashes 
it - looks like its trying to set up a DMA transfer for 0 bytes or something. 
I just added a really horrible hack to the start of sbp2_send_command() to 
check, as follows:

   if (*cmd == 0x1b) {
      SCpnt->sc_data_direction = 3;
   }

Now, eject -r works perfectly. Though thats obviously not a good way to fix 
it :)


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