[U-Boot] [PATCH 02/14] arm: Optionally use existing atags in bootm.c

[Pali Rohár]

On Wednesday 25 January 2012 19:02:45 Marek Vasut wrote:
> > This patch adapts the bootm command so that it can use an existing atags
> > command set up by a previous bootloader.
> 
> Why do you need it?

Default Nokia kernel has patches which using non-standard atags for reporting 
bootmode, bootreason, hw-rev, NOLO version, boot count, ...

Closed-source Maemo application need to know these properties (read via 
/proc/bootreason, ...) and will restart device if there is error.

So U-Boot must can reuse old atags from NOLO and tell it new kernel.

> 
> > If the environment variable
> > "atagaddr" is unset, bootm behaves as normal. If "atagaddr" is set, bootm
> > will use atags address from environment variable and also append new boot
> > args (if specified in u-boot). For example, if a previous boot loader
> > already set up the atags struct at 0x80000100:
> > 
> > setenv atagaddr 0x80000100; bootm 0x80008000
> 
> Can't you set those atags correctly in uboot?
> 

No, because atags are not static (e.g bootreason).

-- 
Pali Rohár
pali.rohar at gmail.com
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