query related to serial console

query related to serial console

[Seetharam Dharmosoth]

Hi all,

Is Linux having 'non-break interface for serial
console' ?

I am currently using Kernel 2.6.7.

how do we know this feature?

Thanks
Seetharam





		
__________________________________________________________
Yahoo! India Answers: Share what you know. Learn something new
http://in.answers.yahoo.com/

Re: query related to serial console

[Erik Mouw]

On Wed, Jan 17, 2007 at 11:26:54AM +0000, Seetharam Dharmosoth wrote:
> Is Linux having 'non-break interface for serial
> console' ?

No idea. Could you explain what a 'non-break interface for serial
console' is?


Erik

-- 
+-- Erik Mouw -- www.harddisk-recovery.com -- +31 70 370 12 90 --
| Lab address: Delftechpark 26, 2628 XH, Delft, The Netherlands

Re: query related to serial console

[Seetharam Dharmosoth]

Generally sysrq will work with serial console right?

suppose system is connected through serial port to the
other system, (ie serial console), at this time we can
fire some set of commands through the serial console.

the sequesnce is as follows  
do ctrl+]
send brk
then some commands

What is my question is con't we pass commands directly

to the console (without send brk signal) ?

This is a feature in Solris..

I am looking in Linux but, uable to find it.

can you please help me

Thanks
Seetharam







--- Erik Mouw <erik@harddisk-recovery.com> wrote:

> On Wed, Jan 17, 2007 at 11:26:54AM +0000, Seetharam
> Dharmosoth wrote:
> > Is Linux having 'non-break interface for serial
> > console' ?
> 
> No idea. Could you explain what a 'non-break
> interface for serial
> console' is?
> 
> 
> Erik
> 
> -- 
> +-- Erik Mouw -- www.harddisk-recovery.com -- +31 70
> 370 12 90 --
> | Lab address: Delftechpark 26, 2628 XH, Delft, The
> Netherlands
> -
> To unsubscribe from this list: send the line
> "unsubscribe linux-kernel" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at 
> http://vger.kernel.org/majordomo-info.html
> Please read the FAQ at  http://www.tux.org/lkml/
> 



		
__________________________________________________________
Yahoo! India Answers: Share what you know. Learn something new
http://in.answers.yahoo.com/

Re: query related to serial console

[Randy Dunlap]

On Thu, 18 Jan 2007 04:10:17 +0000 (GMT) Seetharam Dharmosoth wrote:

(please don't top-post)


> Generally sysrq will work with serial console right?
> 
> suppose system is connected through serial port to the
> other system, (ie serial console), at this time we can
> fire some set of commands through the serial console.
> 
> the sequesnce is as follows  
> do ctrl+]
> send brk
> then some commands
> 
> What is my question is con't we pass commands directly
> 
> to the console (without send brk signal) ?
> 
> This is a feature in Solris..
> 
> I am looking in Linux but, uable to find it.
> 
> can you please help me
> 
> Thanks
> Seetharam

Hi,
It's quite possible that I misunderstand your question,
but anyway:

Alt-Sysrq-<key> is a route into the kernel sysrq handler instead
of a route into the shell that the serial console is connected to,
so something needs to signal that condition (like a BREAK).

Or a specialized (serial) console app could know other ways of
recognizing sysrq keys.  Or you could use /proc/sysrq-trigger:
	echo b > /proc/sysrq-trigger


> --- Erik Mouw <erik@harddisk-recovery.com> wrote:
> 
> > On Wed, Jan 17, 2007 at 11:26:54AM +0000, Seetharam
> > Dharmosoth wrote:
> > > Is Linux having 'non-break interface for serial
> > > console' ?
> > 
> > No idea. Could you explain what a 'non-break
> > interface for serial
> > console' is?


---
~Randy

Re: query related to serial console

[Seetharam Dharmosoth]

--- Randy Dunlap <randy.dunlap@oracle.com> wrote:

> On Thu, 18 Jan 2007 04:10:17 +0000 (GMT) Seetharam
> Dharmosoth wrote:
> 
> (please don't top-post)
> 
> 
> > Generally sysrq will work with serial console
> right?
> > 
> > suppose system is connected through serial port to
> the
> > other system, (ie serial console), at this time we
> can
> > fire some set of commands through the serial
> console.
> > 
> > the sequesnce is as follows  
> > do ctrl+]
> > send brk
> > then some commands
> > 
> > What is my question is con't we pass commands
> directly
> > 
> > to the console (without send brk signal) ?
> > 
> > This is a feature in Solris..
> > 
> > I am looking in Linux but, uable to find it.
> > 
> > can you please help me
> > 
> > Thanks
> > Seetharam
> 
> Hi,
> It's quite possible that I misunderstand your
> question,
> but anyway:
> 
> Alt-Sysrq-<key> is a route into the kernel sysrq
> handler instead
> of a route into the shell that the serial console is
> connected to,
> so something needs to signal that condition (like a
> BREAK).
> 
> Or a specialized (serial) console app could know
> other ways of
> recognizing sysrq keys.  Or you could use
> /proc/sysrq-trigger:
> 	echo b > /proc/sysrq-trigger
> 
Hi Randy,

It's ok.
Thanks for reply.

I have one doubt in this regard.
1) once we connected to the serial console we don't
   want to login into the shell.
   (without login into the shell we want to fire the
   sysrq command like b, r m, etc.)

 for this I am doing like 
  grabing the serial console then
  doing ctrl+]
  so that getting 
              telnet> 
now i want to give command like b, m ,r etc.

but it is not accepting my commands until I do 
telnet> send brk

can you please explain me why like this behavior ?

Thanks
Seetharam

  



> 
> > --- Erik Mouw <erik@harddisk-recovery.com> wrote:
> > 
> > > On Wed, Jan 17, 2007 at 11:26:54AM +0000,
> Seetharam
> > > Dharmosoth wrote:
> > > > Is Linux having 'non-break interface for
> serial
> > > > console' ?
> > > 
> > > No idea. Could you explain what a 'non-break
> > > interface for serial
> > > console' is?
> 
> 
> ---
> ~Randy
> 



		
__________________________________________________________
Yahoo! India Answers: Share what you know. Learn something new
http://in.answers.yahoo.com/

Re: query related to serial console

[Russell King]

On Thu, Jan 18, 2007 at 05:39:15AM +0000, Seetharam Dharmosoth wrote:
> I have one doubt in this regard.
> 1) once we connected to the serial console we don't
>    want to login into the shell.
>    (without login into the shell we want to fire the
>    sysrq command like b, r m, etc.)
> 
>  for this I am doing like 
>   grabing the serial console then
>   doing ctrl+]
>   so that getting 
>               telnet> 
> now i want to give command like b, m ,r etc.
> 
> but it is not accepting my commands until I do 
> telnet> send brk
> 
> can you please explain me why like this behavior ?

If it didn't require a break before hand, merely pressing 'b', 'm' or 'r'
would trigger the sysrq command, which would make it absolutely impossible
to login or type any normal command containing those characters.

-- 
Russell King
 Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
 maintainer of:

Re: query related to serial console

[Seetharam Dharmosoth]

--- Russell King <rmk+lkml@arm.linux.org.uk> wrote:

> On Thu, Jan 18, 2007 at 05:39:15AM +0000, Seetharam
> Dharmosoth wrote:
> > I have one doubt in this regard.
> > 1) once we connected to the serial console we
> don't
> >    want to login into the shell.
> >    (without login into the shell we want to fire
> the
> >    sysrq command like b, r m, etc.)
> > 
> >  for this I am doing like 
> >   grabing the serial console then
> >   doing ctrl+]
> >   so that getting 
> >               telnet> 
> > now i want to give command like b, m ,r etc.
> > 
> > but it is not accepting my commands until I do 
> > telnet> send brk
> > 
> > can you please explain me why like this behavior ?
> 
> If it didn't require a break before hand, merely
> pressing 'b', 'm' or 'r'
> would trigger the sysrq command, which would make it
> absolutely impossible
> to login or type any normal command containing those
> characters.
> 
> -- 
> Russell King
>  Linux kernel    2.6 ARM Linux   -
> http://www.arm.linux.org.uk/
>  maintainer of:
> 
Thanks.

I am not able to find the code path for 
'send brk'

can you please let me know what would be the code path
when we do 'send brk' in linux.

I am interested about 8250 and uart serial driver.

currently using kernel 2.6.7.

Thanks
Seetharam


		
__________________________________________________________
Yahoo! India Answers: Share what you know. Learn something new
http://in.answers.yahoo.com/