Title: RE: Need to identify a physical USB hub
port
I do understand what you're suggesting. Unfortunately, I've still
not got my feet fully on the ground finding api's and docs. I did
notice somewhere that IOMedia (in the IOKit) is defined as an
Objective C class. Two questions:
Where can I find C api's for dealing with IOMedia objects? I don't
do Objective C
.
Where can I find documentation about IOMedia objects? There was
only a very small bit about them in IOKitFundamentals.pdf.
Thank you Chris and list.
At 9:25 AM -0500 5/26/05, Chris Reed wrote:
It's pretty easy,
actually. Find the IOMedia object for the mounted volume, then
walk up that object's parents until you hit an IOUSBDevice, which will
have the locationID property. Or you can use
IORegistryEntrySearchCFProperty() to do it in one call.
There are several
ways to find the IOMedia object for the volume. Perhaps the easiest is
to install a notification handler to watch for new IOMedia
objects.
Another way would be
to use the statfs() call to get the device path. It will be something
like "/dev/disk0s4". Strip the "/dev/", and
search for an IOMedia with a "BSD Name" property with that
value.
There's other ways
as well, but that should give you the basic idea.
Cheers
-chris
From:
usb-bounces+creed=email@hidden
[mailto:usb-bounces+creed=email@hidden] On Behalf
Of B. Mitchell Loebel Sent: Thursday, May 26, 2005 2:22 AM To: Fernando Urbina Cc: email@hidden Subject: Re: Need to identify a physical USB hub
port
Hello list and Fernando:
Perhaps I should clarify my question in the context of
what I now understand about locationID. I originally framed my
question as follows:
"I have an N port hub connected to a Mac USB port.
This hub is permanently connected. Each of the N ports of my external
hub has an SD reader device permanently connected. When a removable SD
flash is inserted into one of the readers I get a volume mounted event
so that I can get the name of the mounted volume and then copy a file
from my hard drive to the SD flash ... no problem. I would like my
code to tell me which physical reader contains the mounted
volume."
Now I see that each flash reader will acquire a 32 bit
locationID when it is connected to the USB bus system and I can pick
up those numbers with a callback which responds to a deviceAdded
notification. Of course, I can't know the ordering of the USB
enumeration, so I can't know which locationID binds with which
physical port. Additionally, my code supports a mount event so that I
have a callback that responds to a flash media being put into one of
the USB reader devices. The fundamental question is how can I
determine which physical port contains the flash media that mounts?
Inasmuch as I can't know which locationID binds with which physical
port, I don't see how knowing the locationIDs for each of the readers
helps me.
At 10:25 PM -0600 5/25/05, Fernando Urbina
wrote:
>I think that the best that you can do is get the
locationID of the device in question. This number is persistent
across restarts, as long as the bus topology remains the same (which
sounds like it will from your description). What you do with
this location ID is up to you ;-)
>
>HTH,
>
>--
>Fernando Urbina
>USB Technology Team
>Apple Computer, Inc.
>
>On May 25, 2005, at 10:07 PM, B. Mitchell Loebel wrote:
>
>> As an example, Windows explorer binds a drive letter to a
reader whether or not the removable flash is inserted in the reader.
And that drive letter persists for the entire session even after the
removable flash has been removed. How can I do the same under OSX ...
Carbon, please?
>>
>>
--
-----
B. Mitchell
Loebel 408 425-9920 cell
Executive Director
The Tech Startup
Connection
(formerly The PARALLEL Processing
Connection)
--
-----
B. Mitchell
Loebel 408 425-9920 cell
Executive
Director
The Tech Startup
Connection
(formerly The PARALLEL Processing
Connection)
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