[1/1] board/raspberrypi/post-build.sh: avoid HDMI login when getty disabled

From: Christophe Blaess <christophe.blaess@logilin.fr>

When the "Run a getty after boot" option is disabled, the inittab line
starting getty on serial console is commented out. But the line running
an HDMI login on Raspberry Pi is still enabled.
With this patch the HDMI line is removed.

Co-authored-by: Christophe Blaess <christophe.blaess@logilin.fr>
Co-authored-by: Stephen Bos <stephen.bos@hagergroup.com>

Signed-off-by: Christophe Blaess <christophe.blaess@logilin.fr>
---
 board/raspberrypi/post-build.sh | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

On Tue, Oct 1, 2019 at 9:58 AM Christophe Blaess <mailist@logilin.fr> wrote:
>
> From: Christophe Blaess <christophe.blaess@logilin.fr>
>
> When the "Run a getty after boot" option is disabled, the inittab line
> starting getty on serial console is commented out. But the line running
> an HDMI login on Raspberry Pi is still enabled.
> With this patch the HDMI line is removed.
>
> Co-authored-by: Christophe Blaess <christophe.blaess@logilin.fr>
> Co-authored-by: Stephen Bos <stephen.bos@hagergroup.com>
>
> Signed-off-by: Christophe Blaess <christophe.blaess@logilin.fr>
> ---
>  board/raspberrypi/post-build.sh | 8 +++++---
>  1 file changed, 5 insertions(+), 3 deletions(-)
>
> diff --git a/board/raspberrypi/post-build.sh b/board/raspberrypi/post-build.sh
> index 5e5eb71100..7f4e1cc8bf 100755
> --- a/board/raspberrypi/post-build.sh
> +++ b/board/raspberrypi/post-build.sh
> @@ -3,9 +3,11 @@
>  set -u
>  set -e
>
> -# Add a console on tty1
>  if [ -e ${TARGET_DIR}/etc/inittab ]; then
> -    grep -qE '^tty1::' ${TARGET_DIR}/etc/inittab || \
> -       sed -i '/GENERIC_SERIAL/a\
> +       # Remove tty1 line
> +       sed -i '/^tty1::/d' ${TARGET_DIR}/etc/inittab
> +       # Add a tty1 line if GENERIC_SERIAL is present (and not commented)
> +       sed -i '/^[^#].*GENERIC_SERIAL/a\
>  tty1::respawn:/sbin/getty -L  tty1 0 vt100 # HDMI console' ${TARGET_DIR}/etc/inittab
>  fi
> +
> --
> 2.17.1
>
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I guess you are using raspberrypi_defconfig as a template for a custom
board configuration. Can't you simply leave
BR2_ROOTFS_POST_BUILD_SCRIPT empty?

Hello Carlos,

> I guess you are using raspberrypi_defconfig as a template for a custom
> board configuration. Can't you simply leave
> BR2_ROOTFS_POST_BUILD_SCRIPT empty?

No, I was using raspberry_defconfig on Raspberry Pi 4 as training 
support to show how to use this option on production systems when we 
don't want any getty (only custom code running on background).

I removed serial console by disabling the "Run a getty option.." but the 
HDMI login was still there.

It's ok to remove the BR2_ROOTFS_POST_BUILD_SCRIPT, but I would rather 
have only disabled the getty option. It seemed more elegant to me.

On Thu, Oct 3, 2019 at 4:54 PM Christophe Blaess <mailist@logilin.fr> wrote:
>
> Hello Carlos,
>
> > I guess you are using raspberrypi_defconfig as a template for a custom
> > board configuration. Can't you simply leave
> > BR2_ROOTFS_POST_BUILD_SCRIPT empty?
>
> No, I was using raspberry_defconfig on Raspberry Pi 4 as training
> support to show how to use this option on production systems when we
> don't want any getty (only custom code running on background).
>
> I removed serial console by disabling the "Run a getty option.." but the
> HDMI login was still there.
>
> It's ok to remove the BR2_ROOTFS_POST_BUILD_SCRIPT, but I would rather
> have only disabled the getty option. It seemed more elegant to me.

I think it's more elegant to solve the problem by means of the
configuration, not by customizing buildroot. The board configurations
an their  post-build and post-mage scripts are mostly examples.

If you need something more sophisticated then it's better to keep them
in a BR2_EXTERNAL, as documented in

    http://www.buildroot.org/downloads/manual/manual.html#customize

Hello Christophe,

On Tue,  1 Oct 2019 14:50:28 +0200
Christophe Blaess <mailist@logilin.fr> wrote:

> -# Add a console on tty1
>  if [ -e ${TARGET_DIR}/etc/inittab ]; then
> -    grep -qE '^tty1::' ${TARGET_DIR}/etc/inittab || \
> -	sed -i '/GENERIC_SERIAL/a\
> +	# Remove tty1 line
> +	sed -i '/^tty1::/d' ${TARGET_DIR}/etc/inittab
> +	# Add a tty1 line if GENERIC_SERIAL is present (and not commented)
> +	sed -i '/^[^#].*GENERIC_SERIAL/a\
>  tty1::respawn:/sbin/getty -L  tty1 0 vt100 # HDMI console' ${TARGET_DIR}/etc/inittab
>  fi

We're fine with the idea, but we would like the implementation to rely
on the BR2 option. So something like this:

# Add a console on tty1
if grep -Eq "^BR2_TARGET_GENERIC_GETTY=y$" ${BR2_CONFIG} && [ -e ${TARGET_DIR}/etc/inittab ]; then
    grep -qE '^tty1::' ${TARGET_DIR}/etc/inittab || \
	sed -i '/GENERIC_SERIAL/a\
tty1::respawn:/sbin/getty -L  tty1 0 vt100 # HDMI console' ${TARGET_DIR}/etc/inittab
fi

Probably the shell syntax is bogus, but you get the point: we want to
rely on BR2_TARGET_GENERIC_GETTY=y to decide whether or not to add a
getty on tty1.

Could you rework your patch in that direction ?

Thanks!

Thomas