Re: [OE-core] [PATCH v2] default-distrovars: Have KERNEL_CONSOLE reference SERIAL_CONSOLES

[Jon Mason <jdmason@kudzu.us>]

On Fri, Aug 30, 2024 at 01:24:29PM +0300, Mikko Rapeli wrote:
> Hi,
> 
> On Thu, Aug 29, 2024 at 05:41:44PM -0400, Jon Mason via lists.openembedded.org wrote:
> > Currently, KERNEL_CONSOLE has a default value of "ttyS0".  However, Arm
> > machines and those using virtio serial prefer to use "ttyAMA0" or "hvc0"
> > (or something else).  These are usually defined by the machine config
> > file as SERIAL_CONSOLES, which has one or more entries.  Take the first
> > one of those instead of ttyS0, but default back to ttyS0 if nothing is
> > set.
> > 
> > Also, use this variable in the efi wic file instead of "ttyS0".
> 
> What kind of issues prompted this patch?
> 
> I ran into possibly similar issues recently where a machine config
> and image is meant for multiple arm64 machines and serial console
> login stopped working on some of them. The kernel console messages
> were on the correct serial port on all machines but systemd-serialgetty recipe
> setup was not. I switched from the yocto specific systemd-serialgetty
> to upstream systemd which fixed all issues and serial getty is
> now on all needed serial ports (based on our test setup):
> 
> systemd_%.bbappend:
> 
> PACKAGECONFIG:append = " serial-getty-generator"
> 
> In our setup we also can't set the default console via kernel command line
> since that changes between machines.

The origin of this is getting poky-altcfg working on fvp-base.
systemd wasn't printing to term because console wasn't specified in
the meta-arm efi-disk.wks.in file, which is based on 
scripts/lib/wic/canned-wks/mkefidisk.wks

For portability, this needed to be a variable, and KERNEL_CONSOLE
seems like the right choice.  There are a lot of arm based machines
out there with ttyAMA0 and a few that are ttyS0.  So it cannot be a
arch based choice, and the machine conf file probably already has
SERIAL_CONSOLES set.  So, we can be dynamic here and get the proper
value for most things.

Now, we could be super smart and add all of the consoles in
SERIAL_CONSOLES, but I think that might be a bit too much.

Anyway, probably a few more wks changes coming to allow me to remove
them from meta-arm.

Thanks,
Jon

> 
> Cheers,
> 
> -Mikko
> 
> > Signed-off-by: Jon Mason <jdmason@kudzu.us>
> > ---
> >  meta/conf/distro/include/default-distrovars.inc | 3 ++-
> >  scripts/lib/wic/canned-wks/mkefidisk.wks        | 2 +-
> >  2 files changed, 3 insertions(+), 2 deletions(-)
> > 
> > diff --git a/meta/conf/distro/include/default-distrovars.inc b/meta/conf/distro/include/default-distrovars.inc
> > index 7554081e8b1a..976ff4adc526 100644
> > --- a/meta/conf/distro/include/default-distrovars.inc
> > +++ b/meta/conf/distro/include/default-distrovars.inc
> > @@ -1,7 +1,8 @@
> >  QA_LOGFILE = "${TMPDIR}/qa.log"
> >  
> >  OEINCLUDELOGS ?= "yes"
> > -KERNEL_CONSOLE ?= "ttyS0"
> > +# if SERIAL_CONSOLES is set, take the first device entry.  Otherwise use ttyS0 as the default
> > +KERNEL_CONSOLE ?= "${@d.getVar('SERIAL_CONSOLES').split(' ')[0].split(';')[1]},${@d.getVar('SERIAL_CONSOLES').split(' ')[0].split(';')[0] or 'ttyS0'}"
> >  KEEPUIMAGE ??= "yes"
> >  
> >  DEFAULT_IMAGE_LINGUAS = "en-us en-gb"
> > diff --git a/scripts/lib/wic/canned-wks/mkefidisk.wks b/scripts/lib/wic/canned-wks/mkefidisk.wks
> > index 9f534fe18471..5fa6682a9e10 100644
> > --- a/scripts/lib/wic/canned-wks/mkefidisk.wks
> > +++ b/scripts/lib/wic/canned-wks/mkefidisk.wks
> > @@ -8,4 +8,4 @@ part / --source rootfs --ondisk sda --fstype=ext4 --label platform --align 1024
> >  
> >  part swap --ondisk sda --size 44 --label swap1 --fstype=swap
> >  
> > -bootloader --ptable gpt --timeout=5 --append="rootfstype=ext4 console=ttyS0,115200 console=tty0"
> > +bootloader --ptable gpt --timeout=5 --append="rootfstype=ext4 console=${KERNEL_CONSOLE} console=tty0"
> > -- 
> > 2.39.2
> > 
> 
> > 
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