Status of kernel

[Okash Khawaja]

Thanks Samuel. That email thread is helpful too. Appreciate your patience. 

> On 15 Nov 2016, at 18:47, Samuel Thibault <samuel.thibault at ens-lyon.org> wrote:
> 
> Okash Khawaja, on Tue 15 Nov 2016 06:58:24 +0000, wrote:
>>    On Tue, Nov 15, 2016 at 6:36 AM, Samuel Thibault <[2]
>>    samuel.thibault at ens-lyon.org> wrote:
>>> And how will /dev/ttyx be used?
>> 
>>        It won't be used. As a line discipline speakup will plug higher in the
>>        stack.
>> 
>>    Could you explain this more? May be a concrete example?
>> I mean is this something that a user space application will read from?
> 
> Normally what happens, for instance when running a serial mouse driver,
> is that a userland program opens /dev/ttyS0, calls an ioctl to set the
> N_MOUSE line discipline, and then leaves /dev/ttyS0 alone. All the work
> is done by the line discipline, userland doesn't do any read/write on
> the device. I.e. the line discipline catches the data before it reaches
> userland.
> 
>> If so, what is the specific advantage of speakup being line
>> discipline?
> 
> It's simply because that's the way things work for all other drivers
> "over serial lines", like mice, joysticks ppp, gsm, etc. There is then
> no risk for speakup to break at all, these have been working for decades
> without a fuss. And they will work with anything that looks more or less
> like a serial port, be it ISA, PCI, USB, bluetooth, irda, whatever.
> 
>> Please add any links/documentation that will help
>> understand this. Thanks
> 
> Unfortunately line disciplines are a rather obscure area not many people
> work on.
> 
> There is linux/Documentation/serial/tty.txt
> 
>>> Also is there a link to where you pasted your idea from?
>> 
>>        I wrote it.
>> 
>>    Of course. I mean a link to full discussion to get more context.
> 
> There is a thread starting here:
> 
> http://www.spinics.net/lists/linux-serial/msg21752.html
> 
> Samuel