Re: 2.6.24-rc5-mm1

Dave Young
2007-12-17T01:14:25Z

On Dec 14, 2007 11:44 PM, Alan Stern <stern@rowland.harvard.edu> wrote:
> On Fri, 14 Dec 2007, Dave Young wrote:
>
> > Hi,
> > The behaviour of my mp3 player (also act as usb-storage device) seems
> > changed from rc5 to rc5-mm1.
>
> This can't be considered a bug, right?

I'm not sure.

> It's just that the player
> changed from one slightly non-standard behavior to a different slightly
> non-standard behavior.
>
>
> > <dmesg output under rc5>:
> > =========
> > usb 1-7: new high speed USB device using ehci_hcd and address 7
> > usb 1-7: configuration #1 chosen from 1 choice
> > scsi4 : SCSI emulation for USB Mass Storage devices
> > usb-storage: device found at 7
> > usb-storage: waiting for device to settle before scanning
> > scsi 4:0:0:0: Direct-Access Newman mp3 PQ: 0 ANSI: 0 CCS
> > sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
> > sd 4:0:0:0: [sdb] Write Protect is on
> > sd 4:0:0:0: [sdb] Mode Sense: 03 00 80 00
> > sd 4:0:0:0: [sdb] Assuming drive cache: write through
> > sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
> > sd 4:0:0:0: [sdb] Write Protect is on
> > sd 4:0:0:0: [sdb] Mode Sense: 03 00 80 00
> > sd 4:0:0:0: [sdb] Assuming drive cache: write through
> > sdb: sdb1
> > sd 4:0:0:0: [sdb] Attached SCSI removable disk
> > sd 4:0:0:0: Attached scsi generic sg1 type 0
> > usb-storage: device scan complete
> >
> > ==========
> > try mount it (or just blockdev --rereadpt), then write protect become off:
> > ==========
> >
> > sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
> > sd 4:0:0:0: [sdb] Write Protect is off
> > sd 4:0:0:0: [sdb] Mode Sense: 03 00 00 00
> > sd 4:0:0:0: [sdb] Assuming drive cache: write through
> > sd 4:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
> > sd 4:0:0:0: [sdb] Write Protect is off
> > sd 4:0:0:0: [sdb] Mode Sense: 03 00 00 00
> > sd 4:0:0:0: [sdb] Assuming drive cache: write through
> > sdb: sdb1
>
> This output won't appear if you simply mount the device. So how do you
> know that mounting turns off write protect?

This can be observed by eye:
dmesg -> mount -> dmesg

>
> > But under rc5-mm1, after mount command being executed, it is just
> > mouted as read only partition without set the write-protect to off
> >
> > I tried "blockdev --rereadpt", it do set the write-protect to off as rc5 kernel.
> >
> > Below is the output of dmesg under rc5-mm1
> > ==========
> > usb 1-8: new high speed USB device using ehci_hcd and address 6
> > usb 1-8: configuration #1 chosen from 1 choice
> > scsi3 : SCSI emulation for USB Mass Storage devices
> > usb-storage: device found at 6
> > usb-storage: waiting for device to settle before scanning
> > scsi 3:0:0:0: Direct-Access Newman mp3 PQ: 0 ANSI: 0 CCS
> > sd 3:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
> > sd 3:0:0:0: [sdb] Write Protect is on
> > sd 3:0:0:0: [sdb] Mode Sense: 03 00 80 00
> > sd 3:0:0:0: [sdb] Assuming drive cache: write through
> > sd 3:0:0:0: [sdb] 245248 512-byte hardware sectors (126 MB)
> > sd 3:0:0:0: [sdb] Write Protect is on
> > sd 3:0:0:0: [sdb] Mode Sense: 03 00 80 00
> > sd 3:0:0:0: [sdb] Assuming drive cache: write through
> > sdb: sdb1
>
> This looks exactly the same as the output above (except for various
> port, device, and bus numbers).

Yes, but lacks the part of "'Write Protect if off' and other lines".

>
> If you turn on CONFIG_USB_STORAGE_DEBUG for both kernels and compare
> the dmesg output for the mount command, that might highlight the
> difference.

Ok, I will test with do once have time, thanks.

Regards
dave