some 13.1 users encountered problems with their USB storage devices that
worked fine with 3.11 kernels but fail with recent 3.12 (Evergreen)
kernel updates. As this has been already reported twice (bsc#971330,
bsc#973663) and potential third report (bsc#978517) waits for
confirmation, I wrote a short summary of the situation.

This seems to be a generic problem of devices supporting the UAS (USB
attached SCSI) protocol which is designed to replace the older USB mass
storage Bulk Only Transfer (BOT). Devices supporting UAS are mostly
"big" (as in hundreds of gigabytes) external disks.

As there used to be a lot of problems with buggy UAS devices, their
firmware and drivers, openSUSE 13.1 blacklists uas driver by adding line
"blacklist uas" to /etc/modprobe.d/50-blacklist.conf so that regular
usb-storage driver is used instead.

However, the 3.12 kernel comes from SLE12-SP1 which does not have this
general blacklist of uas driver and (at least) some UAS require uas
driver to work unless explicitely told otherwise. There are two ways to
resolve the issue:

1. (prefered) Disable the "blacklist uas" statement by commenting out
the line in /etc/modprobe.d/50-blacklist.conf (insert "#" at the
beginning). As the driver might be needed as early as in the initial
ramdisk, after editing the file, run "mkinitrd -f" and reboot.

2. Keep uas blacklisted and allow usb-storage to be used for your UAS
capable device. This can be achieved by adding line like

  options usb-storage quirks=0xVVVV:0xPPPP:u

with VVVV and PPPP replaced by USB vendor and product id of your device
(these can be found in lsusb output on system where the device works) to
file /etc/modprobe.d/99-local.conf  Again, run "mkinitrd -f" and reboot.

There is also the option of providing sysconfig package update disabling
the blacklist line but I'm a bit afraid this might break things for
people with devices where the support is still buggy (as openSUSE is
exposed to much wider range of defices than SLE). Another option would
be patching the Evergreen 13.1 kernel to allow using usb-storage for all
UAS capable devices without requiring the per-device quirks. I'm not
sure how much risk this would be.

                                                          Michal Kubecek

Evergreen mailing list

Reply via email to