Alan Stern wrote:
Um, when you say it does the job, what do you mean?
It traps the error and prevents the kernel from crashing.
The job it was _intended_ to do was to prove that your problems are
caused by hardware errors rather than software bugs. If the patch
causes the problems to stop, without printing any error messages in the
log, then it does indeed prove this. After all, the only places the
patch changes any persistent values are after it prints an error
message.
It did print out error messages:
usb 4-2: new full speed USB device using ohci_hcd and address
2
usb 4-2: New USB device found, idVendor=093a,
idProduct=2460
usb 4-2: New USB device strings: Mfr=1, Product=2,
SerialNumber=0
usb 4-2: Product: CIF Single
Chip
usb 4-2: Manufacturer: Pixart Imaging
Inc.
usb 4-2: configuration #1 chosen from 1
choice
[root@X-Linux]:~ # modprobe
gspca_pac207
Linux video capture interface:
v2.00
gspca: main v2.8.0
registered
gspca: probing
093a:2460
pac207: Pixart Sensor ID 0x27 Chips ID
0x09
pac207: Pixart PAC207BCA Image Processor and Control Chip detected
(vid/pid 0x093A:0x2460)
gspca: video0
created
usbcore: registered new interface driver
pac207
pac207:
registered
[root@X-Linux]:~ #
capture-example
......................................................................
capture-example used greatest stack depth: 5848 bytes
left
[root@X-Linux]:~ #
capture-example
.ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
...ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
.ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
.ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
.ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
....ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
.ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
.ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
.ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
...ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
.ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
.ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
.ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 32 c669f800 c677b800
c677b800
ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..ohci_hcd 0000:00:0b.0: Circular hash: 36 c669f900 c677b900
c677b900
..
[root@X-Linux]:~ #
(Admittedly, I didn't expect the problem to stop; I expected to get a
bunch of messages from the second ohci_err(). Just out of curiosity,
does it make any difference if you remove all those "volatile"s in the
declaration line for td1 and td2?)
It doesn't seem to make much difference.
I noticed that your CPU is a Cyrix. Perhaps it is the culprit. Have
you tried running the program on a different computer?
Yes, on other computers I don't get this error. Same os image. Though I
haven't found a computer with an ohci controller yet.
Alan Stern
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