Date: Thu, 1 Jan 2009 23:24:36 -0800
From: Greg KH <gregkh@suse.de>
To: Mark Lord <lkml@rtr.ca>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>, linux-usb@vger.kernel.org
Subject: Re: libusb broken on 2.6.28 x86_64 ?
Message-ID: <20090102072436.GA3444@suse.de>
References: <495DB4AC.50602@rtr.ca> <495DBBC1.7040202@rtr.ca>
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On Fri, Jan 02, 2009 at 02:01:21AM -0500, Mark Lord wrote:
> Mark Lord wrote:
>> I'm trying to use 2.6.28 for the first time on an x86_64 box here
>> with devices controlled by libusb.  The devices work on the first
>> access, but then fail on all subsequent accesses.  Unplugging/replugging
>> causes them to work again for a single subsequent access.
>> This is with two completely different USB gadgets:
>> a VFD alphanumeric display, and an FTDI serial device in bitbang mode.
>> Did something break in 2.6.28 for libusb devices ??
> ..
>
> Mmm.. broken only for 64-bit userspace, it seems.
>
> I've recompiled the same app against 32-bit libs,
> and it works just fine on that 64-bit system,
> as well as on 32-bit systems.
>
> But not when compiled for pure 64-bit operation on a 64-bit system.
>
> Looks tricky .. must be a change somewhere that assumes
> a pointer/long is 32-bits or something.

Which version of libusb, a new one was just released a few weeks ago
that fixes a lot of problems reported in the older libusb versions, and
made things much faster to boot.  You might want to check it out.

Hope this helps,

greg k-h
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