[U-Boot] ATAGS for Tegra, Sunxi, etc.

[Ian Campbell]

On Thu, 2015-12-17 at 07:40 +0100, Karsten Merker wrote:
> On Thu, Dec 17, 2015 at 01:59:57PM +0900, Masahiro Yamada wrote:
> > 2015-12-17 13:58 GMT+09:00 Masahiro Yamada <yamada.masahiro at socionext.c
> > om>:
> > > Hi,
> > > 
> > > I noticed some well-maintained new SoC families still
> > > define CONFIG_CMDLINE_TAG.
> > > 
> > > 
> > > For example,
> [...]
> > > include/configs/sunxi-common.h
> > > 
> > >  #define CONFIG_SETUP_MEMORY_TAGS
> > >  #define CONFIG_CMDLINE_TAG
> > >  #define CONFIG_INITRD_TAG
> > >  #define CONFIG_SERIAL_TAG
> 
> > > Do they still use ATAGS, not device tree?
> 
> Sunxi uses devicetree for mainline kernels, but AFAIK ATAG
> support is necessary to enable booting legacy vendor kernels.
> There is still new sunxi-based hardware sold today that comes
> with legacy 3.4-based kernels.

That legacy kernel is FEX (allwinners own description blob) based, I don't
know to what extent that involves ATAGs in some way though.

There are also people who use the 3.4 based fork from linux-sunxi.org, but
I don't know if that is DT or ATAGS or FEX.

A dependency on CONFIG_OLD_SUNXI_KERNEL_COMPAT might be an option depending
on what the kernels need, Hans probably knows better than I do.

Ian.

> CCing Hans de Goede and Ian Cambell (sunxi maintainers).

> 
> Regards,
> Karsten