[yocto] thud, beaglebone-yocto.conf: SERIAL_CONSOLES setting

[Khem Raj]

On Fri, Nov 2, 2018 at 2:02 AM Kevin Hao <kexin.hao at windriver.com> wrote:
>
> On Fri, Nov 02, 2018 at 09:01:34AM +0100, Heiko Schocher wrote:
> > Hello Kevin,
> >
> > Am 01.11.2018 um 03:18 schrieb Kevin Hao:
> > > On Wed, Oct 31, 2018 at 02:23:00PM +0100, Heiko Schocher wrote:
> > > > Hello all,
> > > >
> > > > just builded core-image-minimal with current head of thud branch for
> > > > the beaglebone-yocto machine, with linux 4.14.x LTS "Linux version 4.14.78",
> > > > installed the resulting sd card image and boot it, and get:
> > > >
> > > > INIT: Id "O0" respawning too fast: disabled for
> > > > 5 minutes
> > > >
> > > > Reason seems to be:
> > > >
> > > > meta-yocto-bsp/conf/machine/beaglebone-yocto.conf
> > > >
> > > > SERIAL_CONSOLES = "115200;ttyO0"
> > > >
> > > > shouldn't this be
> > > >
> > > > SERIAL_CONSOLES = "115200;ttyS0"
> > > >
> > > > With this fix, sd card image boot fine ... may I oversee seomthing
> > > > obvious ?
> > >
> > > No, it should be 'ttyO0'. It is set by the omap serial driver. You can
> > > refer the following in platform_data/serial-omap.h:
> > >    #define OMAP_SERIAL_NAME        "ttyO"
> >
> > Yes, you are right, but I see with linux kernel 4.14.78 from
> >
> > https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.14.y&id=e7405910ca5553eae8744af4e5c03e64ee048cb1
> >
> > and I see:
> >
> > [    0.000000] Linux version 4.14.78 (oe-user at oe-host) (gcc version 8.2.0
> > (GCC)) #1 Thu Nov 1 10:51:09 UTC 2018
> > [    0.000000] CPU: ARMv7 Processor [413fc082] revision 2 (ARMv7), cr=10c5387d
> > [    0.000000] CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache
> > [    0.000000] OF: fdt: Machine model: TI AM335x BeagleBone Black
> > [...]
> > [    0.362878] Serial: 8250/16550 driver, 6 ports, IRQ sharing disabled
> > [    0.365758] 44e09000.serial: ttyS0 at MMIO 0x44e09000 (irq = 30, base_baud = 3000000) is a 8250
> > [    1.030465] console [ttyS0] enabled
> >
> > So definitely a ttyS0 ...
>
> OK, so you don't use the linux-yocto kernel, you must not use the Yocto kernel
> meta either.

I dont think there is such a rule. meta-yocto-bsps are meant as
references and people might want to enhance them.

 The reason that you got a ttyS0 here is that you use the
> 8250_omap.c driver. But in Yocto we use the omap-serial.c driver. You can
> workaround this issue by enabling SERIAL_8250_OMAP_TTYO_FIXUP.
>

omap serial is obsolete why does linux-yocto keeps using it.
seondly, machine config should enable both consoles ttyO0 and ttyS0 if
you know that at least one kernel is using ttyO0

> Thanks,
> Kevin
>
> >
> > bye,
> > Heiko
> > >
> > > Thanks,
> > > Kevin
> > >
> > > >
> > > > bye,
> > > > Heiko
> > > > --
> > > > DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> > > > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> > > > Phone: +49-8142-66989-52   Fax: +49-8142-66989-80   Email: hs at denx.de
> > > > --
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> >
> > --
> > DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
> > HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> > Phone: +49-8142-66989-52   Fax: +49-8142-66989-80   Email: hs at denx.de
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