[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Sylvain LG]

Hello,

I try to use a  Usb to TTL Serial Cable with a Raspberry Pi running the
default system built by Buildroot.
This cable fully works with a Raspbian system, but on the Buidroot one, it
only displays The first line and nothing else:

Uncompressing Linux... done, booting the kernel.

Kernel is configured with thoses options:

>  --- USB Serial Converter support
> [*]   USB Serial Console device support
> [*]   USB Generic Serial Driver


What is still missing?


Thank you,

Sylvain
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[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Vincent]

On 07/19/2014 02:30 PM, Sylvain LG wrote:
> What is still missing?

Hi,

Maybe you need to add some 'console=ttyAMA0,115200' arguments to your
kernel command line?

Best regards,

V.

[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Thomas Petazzoni]

Dear Sylvain LG,

On Sat, 19 Jul 2014 14:30:34 +0200, Sylvain LG wrote:

> I try to use a  Usb to TTL Serial Cable with a Raspberry Pi running the
> default system built by Buildroot.
> This cable fully works with a Raspbian system, but on the Buidroot one, it
> only displays The first line and nothing else:
> 
> Uncompressing Linux... done, booting the kernel.
> 
> Kernel is configured with thoses options:
> 
> >  --- USB Serial Converter support
> > [*]   USB Serial Console device support
> > [*]   USB Generic Serial Driver
> 
> What is still missing?

Using a USB to TTL serial cable has *nothing* to do with USB support on
the RasberryPi side. Look at your cable:

 *) On the PC side, it's connected over USB. So for sure your PC should
    have the appropriate USB drivers, but that's usually built into any
    normal Linux distribution.

 *) On the RasberryPi side, it's connected directly to an UART. There
    is no USB involved at all.

If you can see the bootloader and "Uncompressing Linux... done, booting
the kernel" then it means that your cable is working.

As Vincent suggested, it might be that you didn't pass the appropriate
console= value.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Sylvain LG]

Indeed, your are right.

I've just edited cmdline.txt: now I can see all kernel messages in a screen
session.

But there is still no console (I mean I can't log in).

1 - What should I add to my conf?

2 - I edited directly cmdline.txt on the sdcard since I didn't manage to
make Buildroot rebuild the system with the new cmdline.txt. How can I do
that?

Thank you,

Sylvain








2014-07-19 16:07 GMT+02:00 Thomas Petazzoni <
thomas.petazzoni@free-electrons.com>:

> Dear Sylvain LG,
>
> On Sat, 19 Jul 2014 14:30:34 +0200, Sylvain LG wrote:
>
> > I try to use a  Usb to TTL Serial Cable with a Raspberry Pi running the
> > default system built by Buildroot.
> > This cable fully works with a Raspbian system, but on the Buidroot one,
> it
> > only displays The first line and nothing else:
> >
> > Uncompressing Linux... done, booting the kernel.
> >
> > Kernel is configured with thoses options:
> >
> > >  --- USB Serial Converter support
> > > [*]   USB Serial Console device support
> > > [*]   USB Generic Serial Driver
> >
> > What is still missing?
>
> Using a USB to TTL serial cable has *nothing* to do with USB support on
> the RasberryPi side. Look at your cable:
>
>  *) On the PC side, it's connected over USB. So for sure your PC should
>     have the appropriate USB drivers, but that's usually built into any
>     normal Linux distribution.
>
>  *) On the RasberryPi side, it's connected directly to an UART. There
>     is no USB involved at all.
>
> If you can see the bootloader and "Uncompressing Linux... done, booting
> the kernel" then it means that your cable is working.
>
> As Vincent suggested, it might be that you didn't pass the appropriate
> console= value.
>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com
>
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[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Thomas Petazzoni]

Dear Sylvain LG,

On Sat, 19 Jul 2014 16:42:55 +0200, Sylvain LG wrote:

> I've just edited cmdline.txt: now I can see all kernel messages in a screen
> session.
> 
> But there is still no console (I mean I can't log in).
> 
> 1 - What should I add to my conf?

Change the getty configuration in "System configuration".

> 2 - I edited directly cmdline.txt on the sdcard since I didn't manage to
> make Buildroot rebuild the system with the new cmdline.txt. How can I do
> that?

No idea, that's a RasberryPi specific stuff, and I haven't done enough
RasberryPi to remember.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Sylvain LG]

I changed tty1 to ttyAMA0 and I can log now.

Only kernel messages are displayed, but no daemons messages (for instance,
"Starting sshd" or the public/private key pair generation).

Why?

Can Buildroot be set to configure more than one tty?

Thank you




2014-07-19 17:13 GMT+02:00 Thomas Petazzoni <
thomas.petazzoni@free-electrons.com>:

> Dear Sylvain LG,
>
> On Sat, 19 Jul 2014 16:42:55 +0200, Sylvain LG wrote:
>
> > I've just edited cmdline.txt: now I can see all kernel messages in a
> screen
> > session.
> >
> > But there is still no console (I mean I can't log in).
> >
> > 1 - What should I add to my conf?
>
> Change the getty configuration in "System configuration".
>
> > 2 - I edited directly cmdline.txt on the sdcard since I didn't manage to
> > make Buildroot rebuild the system with the new cmdline.txt. How can I do
> > that?
>
> No idea, that's a RasberryPi specific stuff, and I haven't done enough
> RasberryPi to remember.
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com
>
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[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Thomas Petazzoni]

Dear Sylvain LG,

On Sat, 19 Jul 2014 17:35:42 +0200, Sylvain LG wrote:
> I changed tty1 to ttyAMA0 and I can log now.
> 
> Only kernel messages are displayed, but no daemons messages (for instance,
> "Starting sshd" or the public/private key pair generation).
> 
> Why?

Those messages are displayed on the console, so if you have
console=<your serial port> you should see them.

> Can Buildroot be set to configure more than one tty?

There are two separate things:

 */ The kernel console. This one is configured using the console=
    kernel parameter, and you can have potentially several ones. This
    is where the kernel messages go, as well as the messages of all
    userspace processes that do not explicitly define a tty
    in /etc/inittab.

 */ The tty on which getty processes are started (getty is the program
    that asks for a login). By default, Buildroot only starts one, but
    you can create your own /etc/inittab (stored for example in a root
    filesystem overlay), and in this case you can start as many getty
    programs as you want, on whichever ttys you want.

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] Raspberry + Usb to TTL Serial Cable issue

[Sylvain LG]

Strange. No message other than kernel ones is printed on the console.


2014-07-19 17:41 GMT+02:00 Thomas Petazzoni <
thomas.petazzoni@free-electrons.com>:

> Dear Sylvain LG,
>
> On Sat, 19 Jul 2014 17:35:42 +0200, Sylvain LG wrote:
> > I changed tty1 to ttyAMA0 and I can log now.
> >
> > Only kernel messages are displayed, but no daemons messages (for
> instance,
> > "Starting sshd" or the public/private key pair generation).
> >
> > Why?
>
> Those messages are displayed on the console, so if you have
> console=<your serial port> you should see them.
>
> > Can Buildroot be set to configure more than one tty?
>
> There are two separate things:
>
>  */ The kernel console. This one is configured using the console=
>     kernel parameter, and you can have potentially several ones. This
>     is where the kernel messages go, as well as the messages of all
>     userspace processes that do not explicitly define a tty
>     in /etc/inittab.
>
>  */ The tty on which getty processes are started (getty is the program
>     that asks for a login). By default, Buildroot only starts one, but
>     you can create your own /etc/inittab (stored for example in a root
>     filesystem overlay), and in this case you can start as many getty
>     programs as you want, on whichever ttys you want.
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com
>
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