# Re: \[RFC/PATCH 2/3\] of: add of\_lookup\_stdout() utility function

- From: Benjamin Herrenschmidt \<benh@kernel.crashing.org\>
- Date: 2008-08-07 22:38:30 
- List: linuxppc-dev
- Page: https://ratatoskr.run/linuxppc-dev/2008/08/9444318
- Thread: https://ratatoskr.run/linuxppc-dev/2008/08/9444193/t.md

```text
On Wed, 2008-08-06 at 00:35 -0600, Grant Likely wrote:
> On Wed, Aug 6, 2008 at 12:32 AM, David Miller [ref] wrote:
> > From: Grant Likely <redacted>
> > Date: Wed, 06 Aug 2008 00:02:44 -0600
> >
> >> of_lookup_stdout() is useful for figuring out what device to use as output
> >> for early boot progress messages.  It returns the node pointed to by the
> >> linux,stdout-path property in the chosen node.
> >>
> >> Signed-off-by: Grant Likely <redacted>
> >
> > On sparc platforms this is obtained differently.  We obtain the 32-bit
> > instance value of "/chosen/stdout" and convert that into a prom device
> > node path using "instance-to-path".
> 
> How about if I modify it to try both methods?

The sparc method however cannot be used on powerpc because it requires
a call to OF to do the "live" conversion (ie, instance-to-path). In
fact, our /chosen/linux,stdout-path is just a cached result of that
conversion done during boot.

Ben.
```