Re: HEAD UP: non-MPSAFE network drivers to be disabled

In message <483BBC1B.6040905elischer.org>, Julian
Elischer writes:

>However the line discipline was a very convenient place
for netgraph 
>to hook in without leaving the kernel. If you can supply
an equally
>effective way to hook into a serial device in such a way
that it 
>appears to be a source/sink of bits then I don't care
about
>line disciplins, but until you have a suggested
replacement then leave 
>them alone. There are MANY people using mpd with the
netgraph ppp 
>moduel hooked directly to the serial port via the
netgraph line 
>discipline.

What exact value of "MANY" are we talking about
here, and do you
have any evidence that the systems in question will be
updated
to FreeBSD-8.0-RELEASE or later ?

If, contrary to my expectation, that you can show a real
market
here, then we should make a better interface than linedisc
for
such hooks into serial ports.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
phkFreeBSD.ORG         | TCP/IP since RFC 956
FreeBSD committer       | BSD since 4.3-tahoe    
Never attribute to malice what can adequately be explained
by incompetence.
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Poul-Henning Kamp wrote:
> In message <483BBC1B.6040905elischer.org>, Julian
Elischer writes:
> 
>> However the line discipline was a very convenient
place for netgraph 
>> to hook in without leaving the kernel. If you can
supply an equally
>> effective way to hook into a serial device in such
a way that it 
>> appears to be a source/sink of bits then I don't
care about
>> line disciplins, but until you have a suggested
replacement then leave 
>> them alone. There are MANY people using mpd with
the netgraph ppp 
>> moduel hooked directly to the serial port via the
netgraph line 
>> discipline.
> 
> What exact value of "MANY" are we talking
about here, and do you
> have any evidence that the systems in question will be
updated
> to FreeBSD-8.0-RELEASE or later ?

judging by the bug reports when things get broken there are
still a
lot of people connected to the internet via dial up lines in
places
off the beaten track, and still a lot of people who when
travelling
do use dialup still. Some of these also use mpd. I can not
say how 
many plan to keep using this in the future but it may be
that the 
simplest answer is a completely separate sio driver that
just has netgraph hooks. I haven't talked with Ed yet but
there
may be may ways to solve this problem.

One that comes to mind is tha tthe way netgraph hooks to
other modules
assumes a possible queueing of data, and that decoupling
could
make it a lot easier to connect tehm that was required for
slip and
ppp.


> 
> If, contrary to my expectation, that you can show a
real market
> here, then we should make a better interface than
linedisc for
> such hooks into serial ports.
> 

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On May 27, 2008, at 1:12 AM, Julian Elischer wrote:

> judging by the bug reports when things get broken there
are still a
> lot of people connected to the internet via dial up
lines in places
> off the beaten track, and still a lot of people who
when travelling
> do use dialup still. Some of these also use mpd. I can
not say how  
> many plan to keep using this in the future but it may
be that the  
> simplest answer is a completely separate sio driver
that
> just has netgraph hooks. I haven't talked with Ed yet
but there
> may be may ways to solve this problem.

Take a look at uart(4). It has been designed to allow
different
kernel interfaces. It currently supports TTYs and keyboards.
It
should not be too hard to have it hook into netgraph.

FYI,

-- 
Marcel Moolenaar
xcllntmac.com



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Marcel Moolenaar wrote:
> On May 27, 2008, at 1:12 AM, Julian Elischer wrote:
> 
>> judging by the bug reports when things get broken
there are still a
>> lot of people connected to the internet via dial up
lines in places
>> off the beaten track, and still a lot of people who
when travelling
>> do use dialup still. Some of these also use mpd. I
can not say how 
>> many plan to keep using this in the future but it
may be that the 
>> simplest answer is a completely separate sio driver
that
>> just has netgraph hooks. I haven't talked with Ed
yet but there
>> may be may ways to solve this problem.
> 
> Take a look at uart(4). It has been designed to allow
different
> kernel interfaces. It currently supports TTYs and
keyboards. It
> should not be too hard to have it hook into netgraph.
> 
> FYI,
> 


While this is a good idea on it's own, the difference
between
what that achieves and what a line discipline achieves is
that
a line disciplin is hardware independent and can even be
used
on a virtual device.

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Julian Elischer wrote:
>
> While this is a good idea on it's own, the difference
between
> what that achieves and what a line discipline achieves
is that
> a line disciplin is hardware independent and can even
be used
> on a virtual device.
I was under the impression that the back-end for UART was
light weight 
enough that it could be used as a virtual device.

For example: Many years ago I tried to get the WinModem
working in my 
IBM ThinkPad T23. UART lends itself well to being a wrapper
for the DSP 
microcode without having any of the historical tty baggage.

In the case of UART the "translation shim" moves
from on top of the 
device node to underneath, in much the same way as has
happened for GEOM.

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On May 27, 2008, at 10:50 AM, Julian Elischer wrote:

> Marcel Moolenaar wrote:
>> On May 27, 2008, at 1:12 AM, Julian Elischer
wrote:
>>> judging by the bug reports when things get
broken there are still a
>>> lot of people connected to the internet via
dial up lines in places
>>> off the beaten track, and still a lot of people
who when travelling
>>> do use dialup still. Some of these also use
mpd. I can not say how  
>>> many plan to keep using this in the future but
it may be that the  
>>> simplest answer is a completely separate sio
driver that
>>> just has netgraph hooks. I haven't talked with
Ed yet but there
>>> may be may ways to solve this problem.
>> Take a look at uart(4). It has been designed to
allow different
>> kernel interfaces. It currently supports TTYs and
keyboards. It
>> should not be too hard to have it hook into
netgraph.
>> FYI,
>
>
> While this is a good idea on it's own, the difference
between
> what that achieves and what a line discipline achieves
is that
> a line disciplin is hardware independent and can even
be used
> on a virtual device.

True, but you said:
"... the simplest answer is a completely separate sio
driver...".

This, besides not being true, is just as hardware dependent
as
uart(4) is. It seems to me that you've conveniently changed
the
subject to match your point of view 

-- 
Marcel Moolenaar
xcllntmac.com



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Marcel Moolenaar wrote:
> 
> On May 27, 2008, at 10:50 AM, Julian Elischer wrote:
> 
>> Marcel Moolenaar wrote:
>>> On May 27, 2008, at 1:12 AM, Julian Elischer
wrote:
>>>> judging by the bug reports when things get
broken there are still a
>>>> lot of people connected to the internet via
dial up lines in places
>>>> off the beaten track, and still a lot of
people who when travelling
>>>> do use dialup still. Some of these also use
mpd. I can not say how 
>>>> many plan to keep using this in the future
but it may be that the 
>>>> simplest answer is a completely separate
sio driver that
>>>> just has netgraph hooks. I haven't talked
with Ed yet but there
>>>> may be may ways to solve this problem.
>>> Take a look at uart(4). It has been designed to
allow different
>>> kernel interfaces. It currently supports TTYs
and keyboards. It
>>> should not be too hard to have it hook into
netgraph.
>>> FYI,
>>
>>
>> While this is a good idea on it's own, the
difference between
>> what that achieves and what a line discipline
achieves is that
>> a line disciplin is hardware independent and can
even be used
>> on a virtual device.
> 
> True, but you said:
> "... the simplest answer is a completely separate
sio driver...".
> 
> This, besides not being true, is just as hardware
dependent as
> uart(4) is. It seems to me that you've conveniently
changed the
> subject to match your point of view 


yep 

we need to decide if the aim is to support just serial
ports or any 'tty'.



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On May 27, 2008, at 1:49 PM, Julian Elischer wrote:

> Marcel Moolenaar wrote:
>> On May 27, 2008, at 10:50 AM, Julian Elischer
wrote:
>>> Marcel Moolenaar wrote:
>>>> On May 27, 2008, at 1:12 AM, Julian
Elischer wrote:
>>>>> judging by the bug reports when things
get broken there are  
>>>>> still a
>>>>> lot of people connected to the internet
via dial up lines in  
>>>>> places
>>>>> off the beaten track, and still a lot
of people who when  
>>>>> travelling
>>>>> do use dialup still. Some of these also
use mpd. I can not say  
>>>>> how many plan to keep using this in the
future but it may be  
>>>>> that the simplest answer is a
completely separate sio driver that
>>>>> just has netgraph hooks. I haven't
talked with Ed yet but there
>>>>> may be may ways to solve this problem.
>>>> Take a look at uart(4). It has been
designed to allow different
>>>> kernel interfaces. It currently supports
TTYs and keyboards. It
>>>> should not be too hard to have it hook into
netgraph.
>>>> FYI,
>>>
>>>
>>> While this is a good idea on it's own, the
difference between
>>> what that achieves and what a line discipline
achieves is that
>>> a line disciplin is hardware independent and
can even be used
>>> on a virtual device.
>> True, but you said:
>> "... the simplest answer is a completely
separate sio driver...".
>> This, besides not being true, is just as hardware
dependent as
>> uart(4) is. It seems to me that you've conveniently
changed the
>> subject to match your point of view 
>
>
> yep 
>
> we need to decide if the aim is to support just serial
> ports or any 'tty'.


Agreed. ucom(4) is in scope...

-- 
Marcel Moolenaar
xcllntmac.com



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