[U-Boot] Support of device-tree for PowerPC platform: Query

[Jagdish Gediya]

Hi Bin,

> -----Original Message-----
> From: U-Boot [mailto:u-boot-bounces at lists.denx.de] On Behalf Of Bin Meng
> Sent: Tuesday, July 3, 2018 8:11 PM
> To: Prabhakar Kushwaha <prabhakar.kushwaha at nxp.com>
> Cc: u-boot at lists.denx.de
> Subject: Re: [U-Boot] Support of device-tree for PowerPC platform: Query
> 
> Hi Prabhakar,
> 
> On Mon, Jul 2, 2018 at 11:27 PM, Prabhakar Kushwaha
> <prabhakar.kushwaha at nxp.com> wrote:
> > Dear Bin,
> >
> > Coming back to x86 example.
> >
> >> -----Original Message-----
> >> From: Bin Meng [mailto:bmeng.cn at gmail.com]
> >> Sent: Friday, June 29, 2018 7:03 AM
> >> To: York Sun <york.sun at nxp.com>
> >> Cc: Simon Glass <sjg at chromium.org>; Prabhakar Kushwaha
> >> <prabhakar.kushwaha at nxp.com>; u-boot at lists.denx.de
> >> Subject: Re: [U-Boot] Support of device-tree for PowerPC platform:
> >> Query
> >>
> >> Hi York,
> >>
> >> On Thu, Jun 28, 2018 at 11:32 PM, York Sun <york.sun at nxp.com> wrote:
> >> > On 06/27/2018 10:53 PM, Bin Meng wrote:
> >> > <snip>
> >> >>
> >> >>> Can the DT perhaps go before U-Boot in the flash? We would need a
> >> >>> way to find it though.
> >> >>>
> >> >>
> >> >> I don't see any issue that DT go after U-Boot in the flash. x86
> >> >> does this way, and its reset vector is also the last address of flash.
> >> >>
> >> >
> >> > Big issue. e500 runs from the last address of the flash. We cannot
> >> > put DT after U-Boot.
> >>
> >> Looks you did not get it. I know e500 reset vector is the last 4 bytes below
> 4G.
> >> This is similar to x86. DTB can be put after the u-boot image without
> >> reset vector. You may check how x86 does this.
> >>
> >
> > I tried to search thing for x86 but did not succeed ☹
> >
> 
> You can test x86 build easily with QEMU.
> 
> $ make qemu-x86_defconfig
> $ make V=1
> 
> This way you can see how u-boot.rom image is built.
> 
> > I request you to help me with sample code and boot flow.
> > I will try to understand and see how it can help PowerPC.
> >
> 
> Please see the sample build flow below:
> 
> 1.  objcopy --gap-fill=0xff  -O binary -R .start16 -R .resetvec u-boot u-boot-
> nodtb.bin
> 
> .start16 and .resetvec is the x86 boot vector. This is similar to PPC BookE's reset
> vector. These two sections are removed to generate a new u-boot-nodtb
> binary.
> 
> 2. cat arch/x86/dts/qemu-x86_i440fx.dtb > dts/dt.dtb
>     cat u-boot-nodtb.bin dts/dt.dtb > u-boot-dtb.bin
> 
> Append dtb to the end of the u-boot-nodtb binary and get a new u-boot-dtb
> binary.
> 
> 3. cp dts/dt.dtb u-boot.dtb
>     objcopy --gap-fill=0xff  -O binary -j .start16 -j .resetvec u-boot u-boot-x86-
> 16bit.bin
> 
> Create a binary which contains the reset vector.
> 
> 4. ./tools/binman/binman -d u-boot.dtb -O . -I . -I
> ./board/emulation/qemu-x86 u-boot-x86-16bit.bin
> 
> Use binman to assemble the final u-boot.rom image.

Wouldn't it be similar to CONFIG_OF_EMBED as dtb is embedded in final binary(before start and resetvec sections)?

Thanks,
Jagdish