From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Date: Thu, 17 Dec 2015 10:26:07 +0100 Subject: [U-Boot] ATAGS for Tegra, Sunxi, etc. In-Reply-To: <1450344061.4053.71.camel@hellion.org.uk> References: <20151217064026.GA1883@excalibur.cnev.de> <1450344061.4053.71.camel@hellion.org.uk> Message-ID: <56727FAF.2060304@redhat.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi, On 17-12-15 10:21, Ian Campbell wrote: > 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 >> 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. The 3.4 based kernels use both ATAGS for things like memory size, and fex for other hw config info. I'm not in favor of wrapping things in CONFIG_OLD_SUNXI_KERNEL_COMPAT, because recent 3.4 based kernels can boot without that, and I believe that removing the ATAG support will break this, without really buying us much. Regards, Hans