Re: [PATCH] sysvinit-inittab: support non-busybox-getty on serial consoles

[Richard Purdie <richard.purdie@linuxfoundation.org>]

On Fri, 2019-02-08 at 16:55 +0000, André Draszik wrote:
> On Fri, 2019-02-08 at 14:07 +0000, Richard Purdie wrote:
> > On Fri, 2019-02-08 at 12:02 +0000, André Draszik wrote:
> > > From: André Draszik <andre.draszik@jci.com>
> > > 
> > > Busybox' getty has code to try to make itself a session leader,
> > > whereas util-linux' agetty doesn't. It expects this to happen
> > > from outside.
> > > When getty is not a session leader, many things don't work on
> > > the serial console, e.g. setting the terminal process group,
> > > job control doesn't work, etc.
> > > 
> > > Executing image tests also fails with AssertionErrors, because
> > >     Feb  5 16:12:55 qemuarm getty[590]: /dev/ttyAMA1: cannot get
> > > controlling tty: Operation not permitted
> > >     Feb  5 16:12:55 qemuarm getty[590]: /dev/ttyAMA1: cannot set
> > > process group: Inappropriate ioctl for device
> > > 
> > > Update the start_getty script to invoke getty via the setsid
> > > utility if needed, i.e. if /sbin/getty is not busybox getty.
> > > 
> > > [YOCTO #13058]
> > > 
> > > Signed-off-by: André Draszik <andre.draszik@jci.com>
> > > ---
> > >  meta/recipes-core/sysvinit/sysvinit-inittab/start_getty | 9
> > > ++++++++-
> > >  meta/recipes-core/sysvinit/sysvinit-inittab_2.88dsf.bb  | 1 +
> > >  2 files changed, 9 insertions(+), 1 deletion(-)
> > > 
> > > diff --git a/meta/recipes-core/sysvinit/sysvinit-
> > > inittab/start_getty
> > > b/meta/recipes-core/sysvinit/sysvinit-inittab/start_getty
> > > index e15ae35f90..ae613f1e54 100644
> > > --- a/meta/recipes-core/sysvinit/sysvinit-inittab/start_getty
> > > +++ b/meta/recipes-core/sysvinit/sysvinit-inittab/start_getty
> > > @@ -13,6 +13,13 @@ active_serial=$(grep "serial"
> > > /proc/tty/drivers |
> > > cut -d/ -f1 | sed "s/ *$//")
> > >  # Rephrase input parameter from ttyS target index (ttyS1, ttyS2,
> > > ttyAMA0, etc).
> > >  runtime_tty=$(echo $2 | grep -oh '[0-9]')
> > >  
> > > +# busybox' getty does this itself, util-linux' getty needs extra
> > > help
> > > +getty="/sbin/getty"
> > > +if ! basename $(readlink -f "${getty}") | grep -q busybox \
> > > +    && [ -x "/usr/bin/setsid" ] ; then
> > > +    getty="/usr/bin/setsid ${getty}"
> > > +fi
> > 
> > The reason I'm reluctant to take changes like this is you just
> > added 3
> > fork calls above. This does have a significant effect on boot time
> > on
> > slower devices.
> > 
> > Is there a way we can do a shell string comparison rather than
> > using
> > grep? case statement maybe?
> 
> I've sent a v2.
> 
> Are you aware that there are at least 9 forks in this file for
> something as
> simple as forking a getty?

I'm not familiar with this file in particular.

I know we removed a lot from general startup but a lot has crept in
since then :( 

Cheers,

Richard