Overriding/concatenating kernel command-line with bootargs from dtb?

Florian Fainelli florian at openwrt.org
Mon Jun 11 13:51:30 EDT 2012

Hi Rob,

On Monday 11 June 2012 09:34:33 Rob Herring wrote:
> On 06/08/2012 02:55 AM, Florian Fainelli wrote:
> > Hi all,
> > 
> > I have a specific use case, where two boards using the same SoC have 
> > UART speeds, which is something that I have specified in their 
> > dts files. In order to make sure people don't mess up the configuration, I 
> > prefer not to rely on the bootloader-supplied kernel-command line.
> > 
> > I was kind of expecting that ARM_ATAG_DTB_COMPAT + CMDLINE_EXTEND would 
> > actually concatenate the kernel command-line with the bootargs provided 
> > dtb.
> > 
> > Is this something someone else would need? If so, shall we just make that 
> > happen when the two config symbols mentionned above are enabled, or shall 
> > introduce a 4th kernel command line handling strategy?
> > 
> > Thank you for your answers.
> There was a patch to do this:
> http://www.mail-archive.com/devicetree-
discuss at lists.ozlabs.org/msg10448.html
> Please comment if this works for you.

This patch indeeds work fine for me when I disable ARM_ATAG_DTB_COMPAT. If I 
let it turned on the chosen node is correctly scanned, but its value, is the 
one coming from tag_cmdline() which is actually the bootloader supplied 
commad-line. I will cook up a patch for this, because I expect the 3 command-
lines to be concatened in the end (built-in, atag and dtb).

I don't see any comments from Ben or anyone after Doug sent his version 2 of 
the patch, is there any reason not to merge it?

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