umass causes panic on 7 amd64

[Garrett Wollman]

In article <48076774.4090602 at icyb.net.ua>, avg at icyb.net.ua writes:

>Eh I think I saw something like this myself.
>Do you by a chance have that new device sg in your kernel?
>I assume you do (GENERIC) - try to drop it.
>I am not sure if this is some brokenness of that driver or fighting of
>several USB drivers over the same hardware.

In my experience, umass over EHCI has never worked on any machine
ever, going back to 5.x and over multiple kinds of umass devices.  (I
never saw panics, only triple-fault CPU resets.)  My old workaround
was to disable EHCI in the kernel configuration, but in 7.0 umass just
doesn't work (reads corrupt data, even without going through a
filesystem).  The same device works fine in Windows.  (In fact that
was the workaround I had to resort to during a recent trip.)

FireWire has always worked for me, but consumer A/V devices don't come
with FireWire ports, and my 7.0 machine is a USB-only laptop.  (I can
plug a CF card into my FireWire CF reader and get valid data off it on
my 6.2 desktop, whereas the same CF device fails on the laptop under
7.0.  It worked when the laptop was running 6.2.)

-GAWollman