Re: Converting MIPS to Device Tree

[Florian Fainelli <florian@openwrt.org>]

On Wednesday 08 June 2011 09:15:14 Geert Uytterhoeven wrote:
> On Wed, Jun 8, 2011 at 01:02, David VomLehn <dvomlehn@cisco.com> wrote:
> > I took a look at the issue of passing device trees to the kernel and
> > started by surveying the methods currently in use for passing
> > information from the bootloader to the kernel. I came up with the ten
> > approaches:
> > 
> > How MIPS Bootloaders Pass Information to the Kernel
> > ---------------------------------------------------
> > Apologies for any errors; this was meant more to be a quick survey
> > rather than a detailed analysis.
> > 
> > 6.      a0 - argc
> >        a1 - argv
> >        a2 - non-standard envp
> >        Command line created by concatenating argv strings, starting at
> >        argv[1]. The envp is a pointer to a list of char ptr to name/char
> >        ptr pairs.
> >        Platforms: txx9
> 
> This depends on the actual boot loader. My rbtx4927 has a VxWorks boot
> loader, which just doesn't pass anything.
> 
> Cfr. commit 97b0511ce125b0cb95d73b198c1bdbb3cebc4de2 ("MIPS: TXx9:
> Make firmware parameter passing more robust").

Actually most devices out there OpenWrt is dealing with are in this situation. 
Most of the time because the boot loader was highly hacked and/or locked down.

In the best cases we can get the bootloader to pass a valid command-line to 
the kernel.
--
Florian