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Subject: Re: [PATCH] serial: DCC(JTAG) serial and console emulation support
From: Daniel Walker <dwalker@codeaurora.org>
To: Mike Frysinger <vapier@gentoo.org>
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Date: Thu, 07 Oct 2010 14:14:54 -0700
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On Thu, 2010-10-07 at 17:03 -0400, Mike Frysinger wrote:
> On Thu, Oct 7, 2010 at 16:51, Daniel Walker wrote:
> > On Thu, 2010-10-07 at 22:05 +0100, Alan Cox wrote:
> >> On Thu, 07 Oct 2010 13:36:06 -0700 Daniel Walker wrote:
> >> > On Thu, 2010-10-07 at 21:50 +0100, Alan Cox wrote:
> >> > > > +         Say Y here if you want to install DCC driver as a normal serial port
> >> > > > +         /dev/ttyS0 (major 4, minor 64). Otherwise, it appears as /dev/ttyJ0
> >> > > > +         (major 4, minor 128) and can co-exist with other UARTs, such as
> >> > > > +         8250/16C550 compatibles.
> >> > > > +
> >> > >
> >> > > NAK to both
> >> >
> >> > I would agree if this wasn't strictly for debugging embedded devices in
> >> > difficult situations.. After talking to Mike, it's seems like it would
> >> > be useful to have this as a ttyS* specifically because embedded devices
> >> > won't always create a ttyJ* for you and ttyS* will likely already exist.
> >>
> >> If you are debugging an embedded device you are capable of changing it
> >> (otherwise you wouldn't debug it). Therefore the fact you might need to
> >> tweak the tty creation on the device is not a problem. If you can't
> >> change the device well there is no point debugging it is there !
> >
> > Your making too many assumptions .. You might be able to modify the
> > kernel, and not the userspace. So you couldn't tweak the device
> > creation .. It's much easier in the server world ..
> 
> this driver isnt in the kernel.  there is no ABI to preserve.  if
> people want to use the mainline driver, they can fix their userspace.
> i dont think the "binary userspace" argument is terribly relevant to
> new driver submissions.

It is , what's to stop any userspace from using ttyS0 ? .. There's lots
of binary userspaces in the embedded world, along with many strange
usages ..

Daniel

-- 

Sent by a consultant of the Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.