Status of kernel
John G Heim
jheim at math.wisc.edu
Tue Nov 15 14:31:36 EST 2016
Is that list, linux-serial, the place where most of the discussion on
the status of speakup goes on? I think part of the problem here is that
if you just go by what you hear on this list, you'd get the impression
that nothing is being done.
On 11/15/2016 12:47 PM, Samuel Thibault 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
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--
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John G. Heim; jheim at math.wisc.edu; sip://jheim@sip.linphone.org
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