[U-Boot] bootstopkey reason behind it

[U-Boot] bootstopkey reason behind it

[Paavaanan_T_N at Dell.com]

Hi,

To stop autoboot we have 2 ifdef  (CONFIG_AUTOBOOT_STOP_ [STR2 || STR1] ). Which is very easy and straightforward to implement. Halting a boot with single "Keystroke" is having its own advantages to the user. But, why multiple key support is ignored say like [ctrl + anykey ] combination. Especially, BIOS vendors prefer at least simultaneous pressing of 2 or more keys to halt the boot. Any specific reasons to avoid this. Other than simplicity is there any specific reason to stick on this.

I mean why  simultaneous two key press support is avoided and implemented  a secondary bootstopkey to halt the boot say like CONFIG_AUTOBOOT_STOP_STR2.

Thanks,
Paavaanan.

[U-Boot] bootstopkey reason behind it

[Stefano Babic]

On 02/08/2013 07:58, Paavaanan_T_N at Dell.com wrote:
> Hi,
> 
> To stop autoboot we have 2 ifdef  (CONFIG_AUTOBOOT_STOP_ [STR2 ||
> STR1] ). Which is very easy and straightforward to implement. Halting
> a boot with single "Keystroke" is having its own advantages to the
> user. But, why multiple key support is ignored say like [ctrl +
> anykey ] combination. Especially, BIOS vendors prefer at least
> simultaneous pressing of 2 or more keys to halt the boot. Any
> specific reasons to avoid this. Other than simplicity is there any
> specific reason to stick on this.
> 
> I mean why  simultaneous two key press support is avoided and
> implemented  a secondary bootstopkey to halt the boot say like
> CONFIG_AUTOBOOT_STOP_STR2.

But does not the keyboard send a single key code ? Maybe it is enough
you put in CONFIG_AUTOBOOT_STOP_STR1 the keycode of your CTRL+key.

Best regards,
Stefano Babic



-- 
=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de
=====================================================================

[U-Boot] bootstopkey reason behind it

[Paavaanan_T_N at Dell.com]

I want to configure bootstopkey to  [ctrl + B] combination, So in bootprompt I gave 
=> setenv boostopkey ^B
=> saveenv

Issuing printenv shows 
boostopkey=^B

But, after issuing reset the key combination didn't stopped the autoboot. 
Do my steps are right ? 


-----Original Message-----
From: Stefano Babic [mailto:sbabic at denx.de] 
Sent: Friday, August 02, 2013 5:05 PM
To: N, Paavaanan T
Cc: u-boot at lists.denx.de
Subject: Re: [U-Boot] bootstopkey reason behind it

On 02/08/2013 07:58, Paavaanan_T_N at Dell.com wrote:
> Hi,
> 
> To stop autoboot we have 2 ifdef  (CONFIG_AUTOBOOT_STOP_ [STR2 || 
> STR1] ). Which is very easy and straightforward to implement. Halting 
> a boot with single "Keystroke" is having its own advantages to the 
> user. But, why multiple key support is ignored say like [ctrl + anykey 
> ] combination. Especially, BIOS vendors prefer at least simultaneous 
> pressing of 2 or more keys to halt the boot. Any specific reasons to 
> avoid this. Other than simplicity is there any specific reason to 
> stick on this.
> 
> I mean why  simultaneous two key press support is avoided and 
> implemented  a secondary bootstopkey to halt the boot say like 
> CONFIG_AUTOBOOT_STOP_STR2.

But does not the keyboard send a single key code ? Maybe it is enough you put in CONFIG_AUTOBOOT_STOP_STR1 the keycode of your CTRL+key.

Best regards,
Stefano Babic



--
=====================================================================
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sbabic at denx.de =====================================================================

[U-Boot] bootstopkey reason behind it

[Heiko Schocher]

Hello Paavaanan_T_N at Dell.com

Am 02.08.2013 13:41, schrieb Paavaanan_T_N at Dell.com:
> I want to configure bootstopkey to  [ctrl + B] combination, So in bootprompt I gave
> =>  setenv boostopkey ^B
                 ^

Try "bootstopkey" ...

bye,
Heiko
-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

[U-Boot] bootstopkey reason behind it

[Paavaanan_T_N at Dell.com]

Heiko,

Thanks for the input. I configured with the help of "bootstopkey" only. I am sorry it's a typo error while I copied in the mail thread. I am not sure am I hijacking the list or not. But, let me just want to clear this. To stop autoboot, one option which I choose is "bootstopkey". I enabled this in ifdef's in the code. Now, the issue is how to give Ctrl key as an input. Because, "setenv bootstopkey b" makes the boot halts. How to do this for [ctrl + b] combination. I tried  "setenv bootstopkey ^B ". It is saved successfully but it treat it separately as "^" and "b" not as Ctrl+b. So, this is the issue.. As per the design do this support this combination or do we don't care about this. I am not clear on this part.

-----Original Message-----
From: Heiko Schocher [mailto:hs at denx.de] 
Sent: Friday, August 02, 2013 5:20 PM
To: N, Paavaanan T
Cc: sbabic at denx.de; u-boot at lists.denx.de
Subject: Re: [U-Boot] bootstopkey reason behind it

Hello Paavaanan_T_N at Dell.com

Am 02.08.2013 13:41, schrieb Paavaanan_T_N at Dell.com:
> I want to configure bootstopkey to  [ctrl + B] combination, So in 
> bootprompt I gave =>  setenv boostopkey ^B
                 ^

Try "bootstopkey" ...

bye,
Heiko
-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

[U-Boot] bootstopkey reason behind it

[Wolfgang Denk]

Dear Paavaanan_T_N at Dell.com,

In message <D5A6F3355F664C40AFB65BB1277D8D450193B22639@MAAX7MCDC101.APAC.DELL.COM> you wrote:
>
> To stop autoboot we have 2 ifdef (CONFIG_AUTOBOOT_STOP_ [STR2 ||
> STR1] ). Which is very easy and straightforward to implement. Halting
> a boot with single "Keystroke" is having its own advantages to the
> user. But, why multiple key support is ignored say like [ctrl +
> anykey ] combination. Especially, BIOS vendors prefer at least
> simultaneous pressing of 2 or more keys to halt the boot. Any
> specific reasons to avoid this. Other than simplicity is there any
> specific reason to stick on this.

BIOSes and BIOS compatible extension cards (say, PCI controllers) are
usually a major PITA when you are not working in an environment where
you have a real keyboard attached.  We're dealing with embedded
devices here, and often we have only communication paths like a serial
port (eventually even over a modem line), or netconsole.

Have you ever tried to transmit some "ALT + some_key" control
sequences over a serial port?

> I mean why simultaneous two key press support is avoided and
> implemented a secondary bootstopkey to halt the boot say like
> CONFIG_AUTOBOOT_STOP_STR2.

This is done because usually we do not have a real keyboard.  So
anything that cannot be mapped into the standard ASCII character set
cannot be used here.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Any fool can make things bigger, more complex, and more  violent.  It
takes  a  touch  of  genius  -  and a lot of courage - to move in the
opposite direction.                                 - Albert Einstein