[sle-beta] SLE 15 SP2 - Add serial console access to RPi JeOS

[Malcolm]

On Mon, 2 Mar 2020 19:18:41 +0000
Andreas Faerber <AFaerber at suse.com> wrote:

> Hi Malcolm,
> 
> Am Sonntag, den 23.02.2020, 12:59 -0600 schrieb Malcolm:
> > Console access seems to be missing from the grub options at boot;
> > 
> > cat /etc/default/grub | grep GRUB_CMDLINE_LINUX_DEFAULT
> > 
> > GRUB_CMDLINE_LINUX_DEFAULT="plymouth.enable=0 console=tty quiet
> > root=UUID=f7bb2dae-ab02-4f1f-8dd5-dd615a1ef946 rw "
> > 
> > Added console=ttyS0,115200n8 and grub2-mkconfig -o
> > /boot/grub2/grub.cfg
> > 
> > Image: SLES15-SP2-JeOS.aarch64-15.2-RaspberryPi-PublicBeta.raw.xz  
> 
> Thanks for reporting this. It should be the same behavior as SLE15
> SP1. In our experience most customers did not have a serial adapter
> attached and used HDMI for initial evaluation. I'd be happy to extend
> that to cover serial console by default, but I fear either way it
> will require editing the GRUB command line in menu and/or config.
> 
> What we can offer is to use "console=ttyS0,115200n8 console=tty",
> which would then by default give you the kernel log on serial only by
> default (like openSUSE Tumbleweed does), but I assume you would also
> want to run the jeos-firstboot setup on serial, which would still
> require editing the command line to drop trailing "console=tty".
> Users with HDMI monitor only would then need to remove
> "console=ttyS0,115200n8".
> 
> Also note that the name of the serial device varies between ttyS0,
> ttyAMA0, ttyAMA1 and theoretically more, depending on your Device Tree
> aliases and [extra]config.txt settings. When someone tweaks
> *config.txt or loads DT Overlays, they may need to edit the command
> line, too, if we hardcode it there.
> 
> The Compute Modules on base boards such as MyPi are another scenario
> we need to consider. I think we should be okay there in most cases.
> 
> U-Boot always emits on serial console, so people wanting to use the
> serial pins for HATs (e.g., GPS, modem) may need to take steps such as
> resetting the external devices via GPIO later from userspace or
> disabling serial output in the DT and re-enabling it from U-Boot, so
> they would not suffer much extra from needing to disable kernel output
> on serial, too.
> 
> Would the above order of serial followed by graphical work for you?
> In GRUB you would still need to press 't' for boot menu on serial.
Hi Andreas
Thank you for the detailed explanation and offer to modify which would
work for me :) In saying that, perhaps an alternative option would be
in the Release Notes to advise users what to change for different boot
scenarios?

As long as I can press 't' to get to the grub menu and modify for first
boot it's not an issue.

-- 
Cheers Malcolm °¿° SUSE Knowledge Partner (Linux Counter #276890)
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