Re: speakup bug

From: Samuel Thibault
Date: Sat Mar 03 2012 - 19:43:49 EST


Ted Ts'o, le Sat 03 Mar 2012 19:41:16 -0500, a écrit :
> On Sun, Mar 04, 2012 at 01:21:11AM +0100, Samuel Thibault wrote:
> > Samuel Thibault, le Sun 04 Mar 2012 01:18:06 +0100, a écrit :
> > > Just for the record: what we need is being able to open a serial port
> > > and read/write from inside the kernel. Using a daemon that does the open
> > > and setting up speakup as a line discipline would be possible, but it
> > > then depends on / working, and that's not something e.g. administrators
> > > can really afford depending on.
> >
> > BTW: yes, that does not mean that speakup couldn't use a line discipline
> > already. Sure, still on the TODO list for years too.
>
> Actualy you *can* open a tty from the kernel. Look at how
> /dev/console is opened in kernel_init() in init/main.c.

But that still needs /dev

> If you don't even want a dependency on /, life gets a little harder,
> but is that really that important?

Yes. It does happen that / can not be mounted: disk encryption, disk
failure, nfs failure, etc. And without any feedback, it's very hard to
know what happened.

> The advantages of doing it cleanly
> is that it will work on systems that don't have a normal serial port,
> but only have a USB interface (for example, if you were going to try
> to hack in support for a mobile device or some other embedded system).

Sure! But there should be a way to do it without /, just like the
serial console works on ttyUSB0 without /.

Samuel
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