Hi Simon,
> -----Original Message----- > From: s...@google.com [mailto:s...@google.com] On Behalf Of Simon Glass > Sent: Thursday, June 28, 2018 3:36 AM > To: York Sun <york....@nxp.com> > Cc: Prabhakar Kushwaha <prabhakar.kushw...@nxp.com>; u- > b...@lists.denx.de; Poonam Aggrwal <poonam.aggr...@nxp.com>; Jagdish > Gediya <jagdish.ged...@nxp.com> > Subject: Re: Support of device-tree for PowerPC platform: Query > > Hi, > > On 27 June 2018 at 08:06, York Sun <york....@nxp.com> wrote: > > > > +Simon > > > > On 06/27/2018 01:05 AM, Prabhakar Kushwaha wrote: > > > Hi All, > > > > > > We are trying to add support of device-tree for PowerPC platforms. As > per our analysis following 2 options can be used. > > > > > > a) CONFIG_OF_SEPARATE > > > b) CONFIG_OF_EMBED > > > > > > In PowerPC platforms, reset_vector is always expected at the **last** > address of flash. > > > U-boot binary has reset_vector at last followed by __bss sections(not > present in binary) and must be programmed in such a way that reset_vecrot > lie at **last** address of flash. > > > > > > Hence dtb cannot be appended at last of u-boot binary. > > > > > > So there looks to be following 2 possible solutions > > > a) Use CONFIG_OF_SEPARATE and append dtb at start of u-boot binary. > This require change in flash map because u-boot start address needs to > shifted (due to reset_vector requirements). > > > Exiting offset of env and fman ucode also needs shifting. This > > > approach > requires modification in almost all existing PowerPC platform to adhere to > new **modified** flash map. > > > > > > b) Use CONFIG_OF_EMBED and embed dtb inside u-boot. This way no > change in exiting flash map. But its usage is being discouraged as per > doc/README.fdt-control. > > > > > > > Clearly putting dtb at the very end doesn't work, neither last 4KB. I > > think we either use CONFIG_OF_EMBED (many boards use this way), or try > > "fdtcontroladdr". > > > I discourage CONFIG_OF_EMBED - it is a debug feature. I'm not sure if you > have other options though. > > Can the DT perhaps go before U-Boot in the flash? We would need a way to > find it though. > Thanks for the direction. We will be following approach "a" with updated flash map. We will allocate 1MB for uboot in flash. Out which 64K for DTB and 960KB for u-boot for future increase. We will also update location of env and fman ucode for NXP platforms. --pk --pk _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
