Does anyone still care about BSD ptys?

Does anyone still care about BSD ptys?

[H. Peter Anvin]

Hi all,

Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
thinking of restructuring the pty system slightly to make it more
dynamic and to make use of the new larger dev_t, and I'd like to get
rid of the BSD ptys as part of the same patch.

	-hpa
-- 
PGP public key available - finger hpa@zytor.com
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Just Say No to Morden * The Shadows were defeated -- Babylon 5 is renewed!!

Re: Does anyone still care about BSD ptys?

[David Weinehall]

On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> Hi all,
> 
> Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
> thinking of restructuring the pty system slightly to make it more
> dynamic and to make use of the new larger dev_t, and I'd like to get
> rid of the BSD ptys as part of the same patch.

As long as you make it a 2.7-thing, I don't thing anyone would mind
much...


Regards: David Weinehall
-- 
 /) David Weinehall <tao@acc.umu.se> /) Northern lights wander      (\
//  Maintainer of the v2.0 kernel   //  Dance across the winter sky //
\)  http://www.acc.umu.se/~tao/    (/   Full colour fire           (/

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

David Weinehall wrote:
> On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> 
>>Hi all,
>>
>>Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
>>thinking of restructuring the pty system slightly to make it more
>>dynamic and to make use of the new larger dev_t, and I'd like to get
>>rid of the BSD ptys as part of the same patch.
> 
> As long as you make it a 2.7-thing, I don't thing anyone would mind
> much...
> 

Right, this is basically for 2.6/2.7 depending on if there are any 
stragglers who still use these things...

	-hpa

Re: Does anyone still care about BSD ptys?

[Ricky Beam]

On Sun, 8 Feb 2004, H. Peter Anvin wrote:
>Right, this is basically for 2.6/2.7 depending on if there are any
>stragglers who still use these things...

nettty (whatever you may find it named) uses the BSD pty interface.  I don't
know how much work it would be to get it to use /dev/pts.  I've not used it
for many years, so I cannot say anyone would care if it stopped working.

The code is at least 7 years old (originally written by Livingston.)

--Ricky

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Ricky Beam wrote:
> On Sun, 8 Feb 2004, H. Peter Anvin wrote:
> 
>>Right, this is basically for 2.6/2.7 depending on if there are any
>>stragglers who still use these things...
> 
> nettty (whatever you may find it named) uses the BSD pty interface.  I don't
> know how much work it would be to get it to use /dev/pts.  I've not used it
> for many years, so I cannot say anyone would care if it stopped working.
> 
> The code is at least 7 years old (originally written by Livingston.)
> 

The porting effort is usually trivial assuming one has access to the source.

	-hpa

Re: Does anyone still care about BSD ptys?

[Miquel van Smoorenburg]

In article <c07c67$vrs$1@terminus.zytor.com>,
H. Peter Anvin <hpa@zytor.com> wrote:
>Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
>thinking of restructuring the pty system slightly to make it more
>dynamic and to make use of the new larger dev_t, and I'd like to get
>rid of the BSD ptys as part of the same patch.

bootlogd(8) which is used by Debian and Suse is started as the
first thing at boottime. It needs a pty, and tries to use /dev/pts
if it's there but falls back to BSD style pty's if /dev/pts isn't
mounted - which will be the case 99% of the time.

Mike.

Re: Does anyone still care about BSD ptys?

[viro]

On Mon, Feb 09, 2004 at 08:59:39AM +0000, Miquel van Smoorenburg wrote:
> In article <c07c67$vrs$1@terminus.zytor.com>,
> H. Peter Anvin <hpa@zytor.com> wrote:
> >Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
> >thinking of restructuring the pty system slightly to make it more
> >dynamic and to make use of the new larger dev_t, and I'd like to get
> >rid of the BSD ptys as part of the same patch.
> 
> bootlogd(8) which is used by Debian and Suse is started as the
> first thing at boottime. It needs a pty, and tries to use /dev/pts
> if it's there but falls back to BSD style pty's if /dev/pts isn't
> mounted - which will be the case 99% of the time.

So what's the problem with calling mount(2)?

Re: Does anyone still care about BSD ptys?

[Miquel van Smoorenburg]

On 2004.02.09 11:09, viro@parcelfarce.linux.theplanet.co.uk wrote:
> On Mon, Feb 09, 2004 at 08:59:39AM +0000, Miquel van Smoorenburg wrote:
> > In article <c07c67$vrs$1@terminus.zytor.com>,
> > H. Peter Anvin <hpa@zytor.com> wrote:
> > >Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
> > >thinking of restructuring the pty system slightly to make it more
> > >dynamic and to make use of the new larger dev_t, and I'd like to get
> > >rid of the BSD ptys as part of the same patch.
> > 
> > bootlogd(8) which is used by Debian and Suse is started as the
> > first thing at boottime. It needs a pty, and tries to use /dev/pts
> > if it's there but falls back to BSD style pty's if /dev/pts isn't
> > mounted - which will be the case 99% of the time.
> 
> So what's the problem with calling mount(2)?

Well, nothing really, but removing BSD style support in the 2.6 series
now will break existing installations. Doing it in 2.7 would be fine.

Mike.

Re: Does anyone still care about BSD ptys?

[bill davidsen]

In article <20040209100940.GF21151@parcelfarce.linux.theplanet.co.uk>,
 <viro@parcelfarce.linux.theplanet.co.uk> wrote:
| On Mon, Feb 09, 2004 at 08:59:39AM +0000, Miquel van Smoorenburg wrote:
| > In article <c07c67$vrs$1@terminus.zytor.com>,
| > H. Peter Anvin <hpa@zytor.com> wrote:
| > >Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
| > >thinking of restructuring the pty system slightly to make it more
| > >dynamic and to make use of the new larger dev_t, and I'd like to get
| > >rid of the BSD ptys as part of the same patch.
| > 
| > bootlogd(8) which is used by Debian and Suse is started as the
| > first thing at boottime. It needs a pty, and tries to use /dev/pts
| > if it's there but falls back to BSD style pty's if /dev/pts isn't
| > mounted - which will be the case 99% of the time.
| 
| So what's the problem with calling mount(2)?

Other than making an optional part of the kernel required... Not
impossible but something to consider.
-- 
bill davidsen <davidsen@tmr.com>
  CTO, TMR Associates, Inc
Doing interesting things with little computers since 1979.

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Followup to:  <c09ccl$qkl$1@gatekeeper.tmr.com>
By author:    davidsen@tmr.com (bill davidsen)
In newsgroup: linux.dev.kernel
>
> In article <20040209100940.GF21151@parcelfarce.linux.theplanet.co.uk>,
>  <viro@parcelfarce.linux.theplanet.co.uk> wrote:
> 
> | So what's the problem with calling mount(2)?
> 
> Other than making an optional part of the kernel required... Not
> impossible but something to consider.
> 

With my changes the devpts filesystem will be pretty much an integral
part of the pty system (since the whole idea is to use the devpts
filesystem to keep track of the tty structures) so that's not an
issue.

	-hpa
-- 
PGP public key available - finger hpa@zytor.com
Key fingerprint: 2047/2A960705 BA 03 D3 2C 14 A8 A8 BD  1E DF FE 69 EE 35 BD 74
"The earth is but one country, and mankind its citizens."  --  Bahá'u'lláh
Just Say No to Morden * The Shadows were defeated -- Babylon 5 is renewed!!

Re: Does anyone still care about BSD ptys?

[Olaf Hering]

 On Mon, Feb 09, Miquel van Smoorenburg wrote:

> In article <c07c67$vrs$1@terminus.zytor.com>,
> H. Peter Anvin <hpa@zytor.com> wrote:
> >Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
> >thinking of restructuring the pty system slightly to make it more
> >dynamic and to make use of the new larger dev_t, and I'd like to get
> >rid of the BSD ptys as part of the same patch.
> 
> bootlogd(8) which is used by Debian and Suse is started as the
> first thing at boottime. It needs a pty, and tries to use /dev/pts
> if it's there but falls back to BSD style pty's if /dev/pts isn't
> mounted - which will be the case 99% of the time.

mounting proc and dev/pts is the first thing our boot script does, since
a very long time. So it will not break anything.

-- 
USB is for mice, FireWire is for men!

sUse lINUX ag, nÜRNBERG

Re: Does anyone still care about BSD ptys?

[Nick Craig-Wood]

On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?

I use them quite a lot for testing serial port stuff in shell scripts,
eg connect one process which expects a serial port to /dev/ttys0 and
another to /dev/ptys0.  I expect there is a sane way of doing this new
style pty's - I just don't know it!

-- 
Nick Craig-Wood
ncw1@axis.demon.co.uk

Re: Does anyone still care about BSD ptys?

[Jamie Lokier]

Nick Craig-Wood wrote:
> On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> > Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?
> 
> I use them quite a lot for testing serial port stuff in shell scripts,
> eg connect one process which expects a serial port to /dev/ttys0 and
> another to /dev/ptys0.  I expect there is a sane way of doing this new
> style pty's - I just don't know it!

Look up "Pseudo-Terminals" in the libc info pages.
http://www.delorie.com/gnu/docs/glibc/libc_376.html

-- Jamie

Re: Does anyone still care about BSD ptys?

[Nick Craig-Wood]

On Mon, Feb 09, 2004 at 12:47:39PM +0000, Jamie Lokier wrote:
> Nick Craig-Wood wrote:
> > On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> > > Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?
> > 
> > I use them quite a lot for testing serial port stuff in shell scripts,
> > eg connect one process which expects a serial port to /dev/ttys0 and
> > another to /dev/ptys0.  I expect there is a sane way of doing this new
> > style pty's - I just don't know it!
> 
> Look up "Pseudo-Terminals" in the libc info pages.
> http://www.delorie.com/gnu/docs/glibc/libc_376.html

Interesting but doesn't help my shell script!

-- 
Nick Craig-Wood
ncw1@axis.demon.co.uk

Re: Does anyone still care about BSD ptys?

[Richard B. Johnson]

> On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> > Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?

Only people who want to log-in from the network..... Of course
you could force a re-write of all the stuff like telnet, adding
another layer of bugs that'll take another N years to find and
remove.

I think you really need to leave the "legacy" stuff alone. Somebody
installs a new kernel and then can't log in from the Network. Not
good at all.

Cheers,
Dick Johnson
Penguin : Linux version 2.4.24 on an i686 machine (797.90 BogoMips).
            Note 96.31% of all statistics are fiction.

Re: Does anyone still care about BSD ptys?

[Dominik Kubla]

On Mon, Feb 09, 2004 at 09:00:24AM -0500, Richard B. Johnson wrote:
> > On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> > > Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?
> 
> Only people who want to log-in from the network..... Of course
> you could force a re-write of all the stuff like telnet, adding
> another layer of bugs that'll take another N years to find and
> remove.

What are you talking about?  On my system (Debian Sid) there are no BSD
pty's (i removed the device nodes) and everything works without even a
recompile.

Regards,
  Dominik
-- 
This fortune was brought to you by the people at Hewlett-Packard.

Re: Does anyone still care about BSD ptys?

[Richard B. Johnson]

On Mon, 9 Feb 2004, Dominik Kubla wrote:

> On Mon, Feb 09, 2004 at 09:00:24AM -0500, Richard B. Johnson wrote:
> > > On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> > > > Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?
> >
> > Only people who want to log-in from the network..... Of course
> > you could force a re-write of all the stuff like telnet, adding
> > another layer of bugs that'll take another N years to find and
> > remove.
>
> What are you talking about?  On my system (Debian Sid) there are no BSD
> pty's (i removed the device nodes) and everything works without even a
> recompile.
>
> Regards,
>   Dominik


Really? Then you don't have anybody trying to log-in
from the network using telnet, then do you?

The BSD virtual terminals go in pairs, /dev/ptyp* /dev/ttyp*

Script started on Mon Feb  9 13:19:16 2004
# ls -la /dev/ptyp*
crw-rw-rw-   1 root     root       2,   0 Feb  9 13:17 /dev/ptyp0
crw-rw-rw-   1 root     root       2,   1 Feb  9 13:19 /dev/ptyp1
crw-rw-rw-   1 root     root       2,   2 Feb  5 11:22 /dev/ptyp2
crw-rw-rw-   1 root     root       2,   3 Mar 19  2003 /dev/ptyp3
[SNIPPED...]

# ls -la /dev/ttyp0
# ls -la /dev/ttyp*
crw--w----   1 rjohnson tty        3,   0 Feb  9 13:17 /dev/ttyp0
crw-rw-rw-   1 root     root       3,   1 Feb  9 13:19 /dev/ttyp1
crw-rw-rw-   1 root     root       3,   2 Feb  5 11:22 /dev/ttyp2
crw-rw-rw-   1 root     root       3,   3 Mar 19  2003 /dev/ttyp3
Script done on Mon Feb  9 13:20:03 2004

Here, rjohnson is logged in using telnet. The code is so common
that there is even some C runtime library support in later
C libraries, it's called forkpty(). `man forkpty`. It does a lot
of the dirty-work of using BSD virtual terminals.


Cheers,
Dick Johnson
Penguin : Linux version 2.4.24 on an i686 machine (797.90 BogoMips).
            Note 96.31% of all statistics are fiction.

Re: Does anyone still care about BSD ptys?

[Athanasius]

[-- Attachment #1: Type: text/plain, Size: 978 bytes --]

On Mon, Feb 09, 2004 at 01:27:24PM -0500, Richard B. Johnson wrote:
> Really? Then you don't have anybody trying to log-in
> from the network using telnet, then do you?
> 
> The BSD virtual terminals go in pairs, /dev/ptyp* /dev/ttyp*
> 
> # ls -la /dev/ttyp*
> crw--w----   1 rjohnson tty        3,   0 Feb  9 13:17 /dev/ttyp0

  Then your telnetd needs 'fixing'.  This works fine, with /dev/pts on
my Debian stable/Woody system:

20:56:57 0$ w athan
USER     TTY      FROM              LOGIN@   IDLE   JCPU   PCPU  WHAT
athan    pts/26   XXXXXXXXXXXXXX   20:56    1:04   0.09s  0.09s  -bash

That's a telnet login just started.

  This is specifically using the 'telnetd-ssl' package in Debian.

-Ath
-- 
- Athanasius = Athanasius(at)miggy.org / http://www.miggy.org/
                  Finger athan(at)fysh.org for PGP key
	   "And it's me who is my enemy. Me who beats me up.
Me who makes the monsters. Me who strips my confidence." Paula Cole - ME

[-- Attachment #2: Type: application/pgp-signature, Size: 240 bytes --]

Re: Does anyone still care about BSD ptys?

[Dominik Kubla]

On Mon, Feb 09, 2004 at 01:27:24PM -0500, Richard B. Johnson wrote:
> On Mon, 9 Feb 2004, Dominik Kubla wrote:
> 
> > On Mon, Feb 09, 2004 at 09:00:24AM -0500, Richard B. Johnson wrote:
> > > > On Mon, Feb 09, 2004 at 07:17:27AM +0000, H. Peter Anvin wrote:
> > > > > Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?
> > >
> > > Only people who want to log-in from the network..... Of course
> > > you could force a re-write of all the stuff like telnet, adding
> > > another layer of bugs that'll take another N years to find and
> > > remove.
> >
> > What are you talking about?  On my system (Debian Sid) there are no BSD
> > pty's (i removed the device nodes) and everything works without even a
> > recompile.
> >
> > Regards,
> >   Dominik
> 
> 
> Really? Then you don't have anybody trying to log-in
> from the network using telnet, then do you?

Really? How do you diagnose my system without even logging in?

[kubla@duron] telnet server1
Trying 192.168.xxx.xxx...
Connected to server1.intern.kubla.de.
Escape character is '^]'.
[SSL - attempting to switch on SSL]
[SSL - handshake starting]
[SSL - OK]
Password: 
Last login: Tue Feb 10 12:03:36 2004 from duron.intern.kubla.de on pts/0
Linux server1 2.6.0-1-k7 #2 Sun Jan 11 17:06:46 EST 2004 i686 GNU/Linux

The programs included with the Debian GNU/Linux system are free software;
the exact distribution terms for each program are described in the
individual files in /usr/share/doc/*/copyright.

Debian GNU/Linux comes with ABSOLUTELY NO WARRANTY, to the extent
permitted by applicable law.
You have mail.
[kubla@server1] tty
/dev/pts/0
[kubla@server1] ls -l /dev/pts/0
crw-------    1 kubla    tty      136,   0 Feb 10 12:08 /dev/pts/0


> The BSD virtual terminals go in pairs, /dev/ptyp* /dev/ttyp*
...
> Here, rjohnson is logged in using telnet. The code is so common
> that there is even some C runtime library support in later
> C libraries, it's called forkpty(). `man forkpty`. It does a lot
> of the dirty-work of using BSD virtual terminals.

Try removing you BSD pty's and most likely you will see that telnetd
happily uses System V pty's. If not then you should really update your
telnetd.  Both netkit-telnetd and telnetd-ssl, which is derived from it,
can use System V-ptys since at least 5 years, probably even longer.
If both BSD and System V pty's are present on the system, the code will use
BSD. (That's why i removed the BSD pty's in the first place!)

Regards,
  Dominik
-- 
"Conversion, fastidious Goddess, loves blood better than brick, and feasts
most subtly on the human will."
-- Virginia Woolf, "Mrs. Dalloway"

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Followup to:  <20040210111632.GA1229@intern.kubla.de>
By author:    Dominik Kubla <dominik@kubla.de>
In newsgroup: linux.dev.kernel
> 
> Try removing you BSD pty's and most likely you will see that telnetd
> happily uses System V pty's. If not then you should really update your
> telnetd.  Both netkit-telnetd and telnetd-ssl, which is derived from it,
> can use System V-ptys since at least 5 years, probably even longer.
> If both BSD and System V pty's are present on the system, the code will use
> BSD. (That's why i removed the BSD pty's in the first place!)
> 

Eep!

Using BSD ptys is a security hazard.  They should *definitely* not be
usef preferentially.  On my system (RH9) they aren't used by telnet
even though they exist.

	-hpa
-- 
PGP public key available - finger hpa@zytor.com
Key fingerprint: 2047/2A960705 BA 03 D3 2C 14 A8 A8 BD  1E DF FE 69 EE 35 BD 74
"The earth is but one country, and mankind its citizens."  --  Bahá'u'lláh
Just Say No to Morden * The Shadows were defeated -- Babylon 5 is renewed!!

Re: Does anyone still care about BSD ptys?

[Karl Tatgenhorst]

H. Peter Anvin wrote:

>Hi all,
>
>Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
>thinking of restructuring the pty system slightly to make it more
>dynamic and to make use of the new larger dev_t, and I'd like to get
>rid of the BSD ptys as part of the same patch.
>
>	-hpa
>  
>
Hi,

      Thanks for asking. I had a critical application that depended on 
them until last week and am now happy to say that even they have moved 
on (I protested the small number of available ptys and explained the 
direction that Unix is going with Unix98 style ptys. Now I depend on 
those. I would be very interested in seeing what you do with your pty 
restructuring as I have a large amount of serial devices.

Karl Tatgenhorst

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Karl Tatgenhorst wrote:
>
> Hi,
> 
>      Thanks for asking. I had a critical application that depended on
> them until last week and am now happy to say that even they have moved
> on (I protested the small number of available ptys and explained the
> direction that Unix is going with Unix98 style ptys. Now I depend on
> those. I would be very interested in seeing what you do with your pty
> restructuring as I have a large amount of serial devices.
> 
> Karl Tatgenhorst
>

LOL :)

If the changes I'm working on work out you should be able to have
hundreds of thousands of ptys if you have enough memory.

	-hpa

Re: Does anyone still care about BSD ptys?

[Karl Tatgenhorst]

>
>
>LOL :)
>
>If the changes I'm working on work out you should be able to have
>hundreds of thousands of ptys if you have enough memory.
>
>	-hpa
>
>
>  
>
Sounds sweet, I am limited though by 4 GB of RAM on a dual PIV 2.8 Ghz 
IBM server. Legacy character apps need so much more :-)

Re: Does anyone still care about BSD ptys?

[Albert Cahalan]

H. Peter Anvin writes:

> Does anyone still care about old-style BSD ptys,
> i.e. /dev/pty*?  I'm thinking of restructuring
> the pty system slightly to make it more dynamic
> and to make use of the new larger dev_t, and
> I'd like to get rid of the BSD ptys as part of
> the same patch.

The BSD-style ptys are used all the time for
serial port emulation. The SysV-style ones are
useless for this, since they don't have a fixed
mapping from master to slave. You might make a
symlink from /dev/testbox to /dev/ptyp0, then
configure gdb to use /dev/testbox for remote
debugging. Then you start a remserial process
to connect /dev/ttyp0 with port 7455 on some
terminal server, and on the terminal server you
have remserial connect port 7455 to /dev/C7.
Now, whenever you run gdb, you're debugging
a test box over a serial line connected to the
terminal server. With SysV-style ttys, you
can't set up your config as nicely. The above
would likely have a few extra symlinks BTW.

In your use of the larger dev_t, please keep
the first 2047 or 2048 ptys as they are today.
Let the last major use the full 20-bit minor,
while restricting the first 7 minors to 8 bits.
This avoids breaking userspace software.

For example, due to the lack of /proc/*/tty links,
procps uses min+(maj-136)*256 to guess the number
of a SysV-style pty. A 32-bit dev_t will be handled
correctly by procps 3.2 if you extend the pty usage
as explained above.

Adding /proc/*/tty links solves the problem as
well, subject to a linux-2.7.0 version check.

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Albert Cahalan wrote:
> 
> The BSD-style ptys are used all the time for
> serial port emulation. The SysV-style ones are
> useless for this, since they don't have a fixed
> mapping from master to slave. You might make a
> symlink from /dev/testbox to /dev/ptyp0, then
> configure gdb to use /dev/testbox for remote
> debugging. Then you start a remserial process
> to connect /dev/ttyp0 with port 7455 on some
> terminal server, and on the terminal server you
> have remserial connect port 7455 to /dev/C7.
> Now, whenever you run gdb, you're debugging
> a test box over a serial line connected to the
> terminal server. With SysV-style ttys, you
> can't set up your config as nicely. The above
> would likely have a few extra symlinks BTW.
> 

Eh?!  Have your server process create the appropriate symlinks... 
problem solved.

> In your use of the larger dev_t, please keep
> the first 2047 or 2048 ptys as they are today.
> Let the last major use the full 20-bit minor,
> while restricting the first 7 minors to 8 bits.
> This avoids breaking userspace software.

No bloody way in hell.  However, unless I have a strong reason to the 
contrary I'll keep them on major 136, so your little formula should 
still woprk.

> For example, due to the lack of /proc/*/tty links,
> procps uses min+(maj-136)*256 to guess the number
> of a SysV-style pty. A 32-bit dev_t will be handled
> correctly by procps 3.2 if you extend the pty usage
> as explained above.


> Adding /proc/*/tty links solves the problem as
> well, subject to a linux-2.7.0 version check.

Presumably it should be: subject to an existence check.

	-hpa

Re: Does anyone still care about BSD ptys?

[Albert Cahalan]

On Mon, 2004-02-09 at 12:14, H. Peter Anvin wrote:
> Albert Cahalan wrote:
> > 
> > The BSD-style ptys are used all the time for
> > serial port emulation. The SysV-style ones are
> > useless for this, since they don't have a fixed
> > mapping from master to slave. You might make a
> > symlink from /dev/testbox to /dev/ptyp0, then
> > configure gdb to use /dev/testbox for remote
> > debugging. Then you start a remserial process
> > to connect /dev/ttyp0 with port 7455 on some
> > terminal server, and on the terminal server you
> > have remserial connect port 7455 to /dev/C7.
> > Now, whenever you run gdb, you're debugging
> > a test box over a serial line connected to the
> > terminal server. With SysV-style ttys, you
> > can't set up your config as nicely. The above
> > would likely have a few extra symlinks BTW.
> 
> Eh?!  Have your server process create the appropriate symlinks... 
> problem solved.

1. That isn't what existing software does.

2. The symlinks couldn't be in /dev without
running as root. Using /tmp isn't going to
work if you're emulating serial ports for
something that will tack a /dev on the front,
unless users will put up with "../tmp/foo".

I should mention here that the SysV pty stuff
is nearly 100% undocumented in the man pages.
I get nothing for pts, pty, grantpt...

> > In your use of the larger dev_t, please keep
> > the first 2047 or 2048 ptys as they are today.
> > Let the last major use the full 20-bit minor,
> > while restricting the first 7 minors to 8 bits.
> > This avoids breaking userspace software.
> 
> No bloody way in hell.  However, unless I have a strong reason to the 
> contrary I'll keep them on major 136, so your little formula should 
> still woprk.

I'm glad that my formula will work. I doubt I'm
the only one to be mapping from number to name
though. Other software, and older procps releases,
won't handle pty 256 through 2047 after you make
your proposed change.

If you insist though, increase the procps release
requirement to 3.2.0 with your patch please.

> > For example, due to the lack of /proc/*/tty links,
> > procps uses min+(maj-136)*256 to guess the number
> > of a SysV-style pty. A 32-bit dev_t will be handled
> > correctly by procps 3.2 if you extend the pty usage
> > as explained above.
> 
> > Adding /proc/*/tty links solves the problem as
> > well, subject to a linux-2.7.0 version check.
> 
> Presumably it should be: subject to an existence check.

That too of course, since there might not be a
tty at all. Also, depending on implementation,
some processes started in early boot might not
have a tty name in spite of having a tty.

The version check avoids trying a link that is
known to not exist on current kernels. For a long
time now I've been moving the version. :-(

Re: Does anyone still care about BSD ptys?

[Andries Brouwer]

On Mon, Feb 09, 2004 at 12:18:57PM -0500, Albert Cahalan wrote:

> I should mention here that the SysV pty stuff
> is nearly 100% undocumented in the man pages.
> I get nothing for pts, pty, grantpt...

% man pts
NAME
       ptmx and pts - pseudo-terminal master and slave

% man grantpt
NAME
       grantpt - grant access to the slave pseudotty

% man posix_openpt
NAME
       posix_openpt - open a pseudo-terminal device


I have to conclude that your version of "the man pages"
is older than man-pages-1.55. Current is man-pages-1.66.

Andries

Re: Does anyone still care about BSD ptys?

[Dominik Kubla]

> I should mention here that the SysV pty stuff
> is nearly 100% undocumented in the man pages.
> I get nothing for pts, pty, grantpt...

Update your system! manpages-1.62 includes:

getpt(3)
grantpt(3)
ptsname(3)
unlockpt(3)
pts(4)
ptmx(4)

Now that should be sufficient, shouldn't it?

Regards,
  Dominik Kubla
-- 
In buying horses and taking a wife shut your eyes tight and commend
yourself to God.

Re: Does anyone still care about BSD ptys?

[Andi Kleen]

Miquel van Smoorenburg <miquels@cistron.nl> writes:

> 
> Well, nothing really, but removing BSD style support in the 2.6 series
> now will break existing installations. Doing it in 2.7 would be fine.

It will still break existing installations even in 2.7.  And breaking
early user space is especially nasty to recover from.  Somehow I
cannot believe keeping them around for compatibility is a unduly
burden. Please don't remove them.

-Andi

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Andi Kleen wrote:
> Miquel van Smoorenburg <miquels@cistron.nl> writes:
> 
>>Well, nothing really, but removing BSD style support in the 2.6 series
>>now will break existing installations. Doing it in 2.7 would be fine.
> 
> It will still break existing installations even in 2.7.  And breaking
> early user space is especially nasty to recover from.  Somehow I
> cannot believe keeping them around for compatibility is a unduly
> burden. Please don't remove them.
> 

It's quite possible that their existence block sanitizing the pty code, 
or more specifically, the pty support in the generic tty code.  I'll see 
what I can do about it; it's possible it'll just fall out nicely in the 
end, but I really have no desire to jump through hoops to preserve what 
is a fundamentally broken legancy interface.

	-hpa

Re: Does anyone still care about BSD ptys?

[Joerg Pommnitz]

HPA asked:
 > Does anyone still care about old-style BSD ptys, i.e. /dev/pty*? 

I do! I have an application that demultiplexes multiple serial streams
from a single one (to be exact this implements the multiplexing scheme
specified in 3GPP TS27.010 
(http://www.3gpp.org/ftp/Specs/latest/Rel-5/27_series/27010-500.zip).

The multiplexer uses old-style ptys to export the multiple streams 
to the applications (e.g. there are:
crw-rw-rw-    1 root     root       3, 236 May 21  2002 ttypMuxA0
crw-rw-rw-    1 root     root       3, 237 May 21  2002 ttypMuxA1
crw-rw-rw-    1 root     root       3, 238 May 21  2002 ttypMuxA2
crw-rw-rw-    1 root     root       3, 239 May 21  2002 ttypMuxA3
crw-rw-rw-    1 root     root       2, 236 May 21  2002 ptypMuxA0
crw-rw-rw-    1 root     root       2, 237 May 21  2002 ptypMuxA1
crw-rw-rw-    1 root     root       2, 238 May 21  2002 ptypMuxA2
crw-rw-rw-    1 root     root       2, 239 May 21  2002 ptypMuxA3).

It would be difficult to implement the same thing using SYSV ptys.

Regards
  Joerg


=====
-- 
Regards
       Joerg



	
		
Mit schönen Grüßen von Yahoo! Mail - http://mail.yahoo.de

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Followup to:  <20040209165711.2185.qmail@web41308.mail.yahoo.com>
By author:    =?iso-8859-1?q?Joerg=20Pommnitz?= <pommnitz@yahoo.com>
In newsgroup: linux.dev.kernel
> 
> It would be difficult to implement the same thing using SYSV ptys.
> 

I find that hard to believe, although you might have to create links
dynamically.

	-hpa

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Re: Does anyone still care about BSD ptys?

[Bill Davidsen]

H. Peter Anvin wrote:
> Hi all,
> 
> Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
> thinking of restructuring the pty system slightly to make it more
> dynamic and to make use of the new larger dev_t, and I'd like to get
> rid of the BSD ptys as part of the same patch.
> 
> 	-hpa

Re: Does anyone still care about BSD ptys?

[Bill Davidsen]

H. Peter Anvin wrote:
> Hi all,
> 
> Does anyone still care about old-style BSD ptys, i.e. /dev/pty*?  I'm
> thinking of restructuring the pty system slightly to make it more
> dynamic and to make use of the new larger dev_t, and I'd like to get
> rid of the BSD ptys as part of the same patch.

Sorry, last reply "just went" for some reason... ijn any case I hope the 
number and tone of replies has shown that a number of people DO care, 
and that "you can just program around it with your effort instead of 
mine" isn't going to be popular.

In other words, this sounds more like 2.7 material where people expect 
things to change than something which should just suddenly break in 2.6. 
Violation of Plauger's Law of Least Astonishment and all that.

-- 
I doubt like hell this mailer has a sig...

Re: Does anyone still care about BSD ptys?

[Theodore Ts'o]

On Tue, Feb 10, 2004 at 02:51:43PM -0500, Bill Davidsen wrote:
> Sorry, last reply "just went" for some reason... ijn any case I hope the 
> number and tone of replies has shown that a number of people DO care, 
> and that "you can just program around it with your effort instead of 
> mine" isn't going to be popular.
> 
> In other words, this sounds more like 2.7 material where people expect 
> things to change than something which should just suddenly break in 2.6. 
> Violation of Plauger's Law of Least Astonishment and all that.

I think the discussion has always been that this would be a 2.7 item.  

However, it might be useful to make 2.6 start issueing printk's *now*
when a program uses a BSD pty, so that application programs have
plenty of notice that they will be going away.

						- Ted

Re: Does anyone still care about BSD ptys?

[H. Peter Anvin]

Theodore Ts'o wrote:
> On Tue, Feb 10, 2004 at 02:51:43PM -0500, Bill Davidsen wrote:
> 
>>Sorry, last reply "just went" for some reason... ijn any case I hope the 
>>number and tone of replies has shown that a number of people DO care, 
>>and that "you can just program around it with your effort instead of 
>>mine" isn't going to be popular.
>>
>>In other words, this sounds more like 2.7 material where people expect 
>>things to change than something which should just suddenly break in 2.6. 
>>Violation of Plauger's Law of Least Astonishment and all that.
> 
> 
> I think the discussion has always been that this would be a 2.7 item.  
> 
> However, it might be useful to make 2.6 start issueing printk's *now*
> when a program uses a BSD pty, so that application programs have
> plenty of notice that they will be going away.
> 

The way it looks right now it's not going to matter; it appears that
(optionally) continuing to supporting BSD ptys will "fall out naturally"
at least initially.

Ted, could I ask you to eyeball my patch to see how broken it is?

	-hpa

Re: Does anyone still care about BSD ptys?

[Theodore Ts'o]

On Tue, Feb 10, 2004 at 02:02:49PM -0800, H. Peter Anvin wrote:
> The way it looks right now it's not going to matter; it appears that
> (optionally) continuing to supporting BSD ptys will "fall out naturally"
> at least initially.
> 
> Ted, could I ask you to eyeball my patch to see how broken it is?

Sure, send me your latest version of the patch and I'll take a look at it.

						- Ted