linux-kernel - Re: [PATCH 0/3] Increase the number of USB to serial devices we can support at once

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Date:	Thu, 6 Jun 2013 08:21:31 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Dave Jones <davej@...hat.com>,
	Tobias Winter <tobias@...uxdingsda.de>,
	Bjørn Mork <bjorn@...k.no>,
	Rob Landley <rob@...dley.net>, linux-usb@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] Increase the number of USB to serial devices we can
 support at once

On Thu, Jun 06, 2013 at 11:01:12AM -0400, Dave Jones wrote:
> On Wed, Jun 05, 2013 at 10:54:26AM -0700, Greg KH wrote:
>  > Here are 3 patches that I've tested out on my system with only a small
>  > number of devices, but it seems to work, so why not let others try it
>  > out...
>  > 
>  > These patches make the USB to serial core have the ability to support up
>  > to 3000 devices at once now.  
> 
> I'm curious how this works. What systems have 3000 usb ports ?
> Or are there some kind of multiplexer devices out there ?
> (If so, I'd like a link, I could use one of those).

You don't need a multiplexer, you can have a bunch of different USB root
hubs in PCI slots, with USB hubs plugged into them, and lots of
multi-port USB devices connected to them.  Tobias has such a system with
272 single-port USB to serial devices connected, so it's not impossible
to create.

In thinking about it some more, I'll change that number to 500 for now,
as it's a static array within the tty layer, and then work on making
that dynamic so we don't have any limitations other than the number of
minor numbers for a single major.

thanks,

greg k-h
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