[PATCH] lds: align u-boot-nodtb with 8 bytes boundary

[Simon Glass]

Hi Eugen,

On Thu, 15 Dec 2022 at 03:58, Eugen Hristev <eugen.hristev at microchip.com> wrote:
>
> Newer DTC require that the DTB start address is aligned at 8 bytes.
> In the u-boot.bin case, the u-boot-nodtb.bin is concatenated with the
> DTB, but there is no alignment/padding to the next 8byte aligned address.
> This causes the board to fail booting, because the FDT will claim
> that the DTB inside u-boot.bin is not a valid DTB, it will fail with
> -FDT_ERR_ALIGNMENT.
> To solve this, have the u-boot binary `_end` aligned with 8 bytes.
> The objcopy in the Makefile will create the u-boot-nodtb.bin and it has to
> be truncated to 8 bytes to correspond to the u-boot.map file which will
> have the `_end` aligned to 8 bytes.
> The lds files which use devicetrees have been changed to align the `_end`
> tag with 8 bytes.
>
> This patch is also a prerequisite to have the possibility to update the
> dtc inside u-boot to newer versions (1.6.1+)
>
> Signed-off-by: Eugen Hristev <eugen.hristev at microchip.com>
> ---
> Hi,
>
> I could not test all affected boards, it's an impossible task.
> I tried this on at91 boards which I have, and ran the CI on denx.
> I cannot guarantee that no other boards are affected, so this patch is a bit
> of an RFC.
> If the u-boot-nodtb.bin does not have the size equal with the corresponding
> one in u-boot.map, the binary_size_check will fail at build time with
> something like this:
>
> u-boot.map shows a binary size of 502684
> but u-boot-nodtb.bin shows 502688
>
> Thanks,
> Eugen
>
>  Makefile                                    | 2 ++
>  arch/arm/cpu/armv8/u-boot.lds               | 4 ++--
>  arch/arm/cpu/u-boot-spl.lds                 | 1 +
>  arch/arm/cpu/u-boot.lds                     | 1 +
>  arch/arm/lib/elf_arm_efi.lds                | 5 +++++
>  arch/arm/mach-at91/arm926ejs/u-boot-spl.lds | 2 +-
>  arch/arm/mach-at91/armv7/u-boot-spl.lds     | 2 +-
>  arch/arm/mach-zynq/u-boot-spl.lds           | 2 +-
>  arch/mips/cpu/u-boot.lds                    | 2 +-
>  arch/sandbox/cpu/u-boot.lds                 | 6 ++++++
>  arch/sh/cpu/u-boot.lds                      | 2 ++
>  board/ti/am335x/u-boot.lds                  | 1 +
>  tools/binman/test/u_boot_binman_embed.lds   | 2 +-
>  13 files changed, 25 insertions(+), 7 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 9d84f96481..b4d387bcce 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1317,6 +1317,8 @@ endif
>
>  u-boot-nodtb.bin: u-boot FORCE
>         $(call if_changed,objcopy_uboot)
> +# Make sure the size is 8 byte-aligned.
> +       @truncate -s %8 $@
>         $(BOARD_SIZE_CHECK)

I agree this line is needed, since otherwise we will only get 4-byte
alignment. But it would be better if we could have the linker scripts
fill bytes out to the required alignment. Is that possible?

Reviewed-by: Simon Glass <sjg at chromium.org>

Regards,
Simon