[Skiboot] [PATCH] Set boot consoles to be used by the bootloader

Stewart Smith stewart at linux.vnet.ibm.com
Thu Mar 31 10:35:39 AEDT 2016

Sam Mendoza-Jonas <sam at mendozajonas.com> writes:
> If nothing is specified on the kernel command line the boot console will
> only be displayed on hvc0 by default.
> Specify both tty0 and hvc0 so that the boot console can also be seen on
> the VGA device if it is available.
> Signed-off-by: Sam Mendoza-Jonas <sam at mendozajonas.com>
> ---
> Technically this could also be done by patching it to be the default
> in the kernel (ie. a patch in op-build) but this seems to be a cleaner
> way of setting it for any bootloader we may have.
> Tested on a Habanero and Tuleta machine, although I don't have a monitor
> attached to any Tuletas at the moment.

So... I've been thinking about this for a bit, and my mind returned to
it sometime this morning in a haze of cold+flu meds - and I've started
to think that this may not be the best way to achieve this...

While this probably works on existing configurations okay, my concern is
if people start doing crazy things like adding in serial ports or hvc
consoles and the like....

Should we instead have some kind of notation in the device tree that
then Linux can listen to? I've been digging into the /chosen/stdout
property, but that only gets us one console, which isn't exactly what we

so it kind of seems like we want a new binding, maybe
/chosen/console-path that's a list of devices that firmware hints that a
console should be run on? That way we could avoid something that ends up
being like "console=all" on a command line, and possibly starting
consoles in the wrong place...


Stewart Smith
OPAL Architect, IBM.

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