** Changed in: linux (Ubuntu Jaunty)
Status: In Progress => Fix Committed
** Description changed:
+ SRU justification:
+
+ Impact (from Scott):
+ The ub driver is an old attempt for a slow USB Block Device driver,
+ it hasn't been maintained in quite a while and we don't have an easy
+ way to enable it.
+
+ libusual is a strange mechanism for the kernel to auto-select between
+ usb-storage and ub. It works by stealing the aliases from them both
+ and modprobe'ing (from the kernel) the other module when a device is
+ connected.
+
+ The trouble is that because it's built into the kernel, on machines with
+ particularly fast init, it could be trying to call it before the initramfs
+ has even been switched to - or before the initramfs has called "depmod".
+ In either case, since there's no modules.alias/modules.dep files, the
+ modprobe call with fail and the USB storage device will not be enabled.
+
+ Plugging a second USB storage device in will magically cure the problem.
+
+ Fix: Attched patch to disable those modules. This bumps ABI as the
+ libusual functions go missing. All IDs automagically go over to usb-
+ storage.
+
+ Testcase: Booting from usb storage with a quick host.
+
+ ---
+
Continuing from bug #363038
Pete Graner's problem with the Dell Latitude XT was that the kernel was
calling "modprobe usb-storage" before the initramfs has run "depmod" to
initialise the module db.
This was all crack.
There's no reason to have the kernel call modprobe in this way, it was
caused by something called "libusual" which steals all of usb-storage's
aliases and then modprobes it. The intent is that it allows you to
alternate between "usb-storage" and "ub".
Not only is "ub" very crufty and unmaintained, but we can do that kind
of switching in userspace these days.
Disabling libusual in the kernel config means that usb-storage gets
modprobe aliases just like every other driver, and is loaded by udev
just like every other driver. Race condition solved, laptop boots.
--
Failure to boot from USB - Dell Latitude XT
https://bugs.launchpad.net/bugs/364538
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