kernel params passed by OF/cmdline/"append="

Ryan Wang openspace.wang at gmail.com
Tue Oct 25 00:32:51 EST 2011


2011/10/24 Tony Breeds <tony at bakeyournoodle.com>

> On Sun, Oct 23, 2011 at 12:25:41AM +0800, Ryan Wang wrote:
> > Hi,
> >
> > I know that there are 3 ways to pass params to kernel:
> >     (1) params set in openfirmware
> >     (2) when yaboot up, in the prompt "boot: ", specify the label and
> params
> >     (3) params in the item "append=" of yaboot.conf
> >
> > My question is:
> > How can they combine together? I read some code in yaboot src, but found
> > that
> > only 2 cases are available:
> >       (3) + (1)
> >       (3) + (2)
> > If I set params with method 1, 2 and 3, then I'll get the results as 2 +
> 3
> > only. That is
> >       (1) + (2) + (3) = (3) + (2)
> >
> > Is that right?
>
> Thanks, Tony.

I still have another 2 questions:
       1) Where does boot-file come in effect?
           E.g. I run 'setenv boot-file xmon=on' in the openfirmware, can
the vmlinux booted
           by yaboot get the arg 'xmon=on'?
        2) What's the relationship between boot-file and bootargs?

thanks,


> OF args are passed to the object booted, they are not passed on beyond
> that point.  So if you do something like:
>
> boot net conf=etc/fubar
>
> If the ELF servered up is yaboot, yaboot consumes the conf=etc/fubar and
> uses your methods 2 and 3 to create the boot args for the kernel you
> boot.
>
> If the ELF servered up is a kernel then they're passed on as expected.
>
>
> Yours Tony
>
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