hi,
James Bottomley wrote:
On Fri, 2008-10-24 at 09:05 +0200, Matthias Kaehlcke wrote:
hi,
inserting a Verbatim 4GB USB stick in a ep9307 based device running
kernel 2.6.27 results in the following Oops:
[42949395.050000] usb 1-3: new full speed USB device using ep93xx-ohci
and address 2
[42949395.250000] usb 1-3: configuration #1 chosen from 1 choice
[42949395.260000] scsi0 : SCSI emulation for USB Mass Storage devices
[42949395.270000] usb 1-3: New USB device found, idVendor=13fe,
idProduct=1f23
[42949395.280000] usb 1-3: New USB device strings: Mfr=1, Product=2,
SerialNumber=3
[42949395.280000] usb 1-3: Product: STORE N GO
[42949395.300000] usb 1-3: Manufacturer: Verbatim
[42949395.310000] usb 1-3: SerialNumber: 078813D90478
[42949400.280000] Unable to handle kernel NULL pointer dereference at
virtual address 00000003
[42949400.280000] pgd = c0648000
[42949400.300000] [00000003] *pgd=c0647031, *pte=00000000, *ppte=00000000
[42949400.300000] Internal error: Oops: 13 [#1] PREEMPT
[42949400.300000] Modules linked in:
[42949400.300000] CPU: 0 Not tainted (2.6.27 #3)
[42949400.300000] PC is at scsi_calculate_bounce_limit+0x3c/0x44
Best guess is this line:
if (host_dev && host_dev->dma_mask)
bounce_limit = *host_dev->dma_mask;
I'd guess host_dev->dma_mask contains 0x3 ... could this be some sort of
ARM setup problem?
thanks for having a look!
i could figure out the difference between 2.6.26.3 and 2.6.27 that
triggers the Oops:
diff -u linux-2.6.26.3/include/asm-arm/pci.h
linux-2.6.27/arch/arm/include/asm/pci.h
...
@@ -30,7 +30,7 @@
* The networking and block device layers use this boolean for bounce
* buffer decisions.
*/
-#define PCI_DMA_BUS_IS_PHYS (0)
+#define PCI_DMA_BUS_IS_PHYS (1)
/*
* Whether pci_unmap_{single,page} is a nop depends upon the
...
this change affects the following piece of code in
scsi_calculate_bounce_limit():
if (!PCI_DMA_BUS_IS_PHYS)
return BLK_BOUNCE_ANY;
host_dev = scsi_get_device(shost);
if (host_dev && host_dev->dma_mask)
bounce_limit = *host_dev->dma_mask;
host_dev->dma_mask is 0xffffffff and we try to dereference the pointer
what i don't know is what is the correct fix for the problem, i suppose
there was a good reason to change PCI_DMA_BUS_IS_PHYS ...
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