Re: [Libusb-devel] libusb silently ignores permission errors

[Xiaofan C. <xia...@gm...>]

On 9/15/07, Xiaofan Chen <xia...@gm...> wrote:
> On 9/15/07, Karl O. Pinc <ko...@me...> wrote:
> > Hello,
> >
> > I apologize if this has already been discussed.  The
> > sourceforge page with the archive for this mailing list
> > seems to be down.
> >
> > Apparently libusb silently ignores at least some permission
> > errors, and there is nothing in the API which allows such
> > errors to be reported back to applications.  As a result
> > applications, like lsusb, which report on usb devices must be
> > run as root lest some devices be silently omitted from
> > the report.
> >
> > I can understand having some devices be entirely invisible,
> > as are files in a directory to which the user has no
> > permissions, but that is not the case here.  The devices
> > are visible in the /proc or /dev filesystems, presumably
> > because the usb bus itself, which plays a role similar
> > to a directory, is always readable.  Applications should
> > be able to deliver informative error messages regarding
> > permissions rather than behaving as if the device
> > does not exist.
>
> Sorry about my ignorance about your problem but
> I thought your problem has already fully answered by
> Greg KH.
>
> Maybe another solution is that you can ask the lsusb user
> not to use libusb or write your own lsusb like application.
>

Just yesterday I tried the PICDEM FS USB bootloader under
Ubuntu 7.04 and it is not working well under it. dmesg shows
the device but lsusb does not show it.

So I am thinking that there is a problem with the Debian kernel
which Ubuntu kernel is based on. I have also saw similar report
on the Microchip forum. The same device works fine under the
older Ubuntu 6.06. I also heard that Debian Sid users suffer the
same problem.
http://forum.microchip.com/tm.aspx?m=283378

I then tried Greg KH's USBView and it actually list the device.
Strange. Maybe you can try USBView and see if it actually helps.
http://www.kroah.com/linux/usb/

USBView is available for many distributions including Ubuntu.
It seem to me that it does not use libusb.

Regards,
Xiaofan