Re: linux kernel panic when ejecting ieee1394 ipod

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

(resent to include other lists)

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.


Tracing through the kernel for the CDROMEJECT shows:
drivers/scsi/sd.c/sd_ioctl() 
	-- calls scsi_cmd_ioctl()

drivers/block/scsi_ioctl.c/scsi_cmd_ioctl()
	-- emulates the CDROMEJECT ioctl as a START_STOP unit SCSI packet command

... then that passes through the blockdev/scsi layers until:

drivers/ieee1394/sbp2.c/sbp2scsi_queuecommand()
	-- this function actually works fine - it must be either in the callback 
handler when the command completes (?) or sometime afterwards.

The last SCSI command received by sbp2 before the crash is:

1b 00 00 02 00

Which is definitely what scsi_cmd_ioctl() is setting up.


CDROMEJECT works on other scsi devices - e.g. my USB storage pendrive appears 
as a SCSI drive, and can be "safely removed" by simply calling a CDROMEJECT 
ioctl.


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