[Buildroot] [PATCH v2 1/1] boot/uboot/uboot.mk: add stripped u-boot.elf support

[Luca Ceresoli]

Hello Neal,

On Mon, 21 Nov 2022 22:36:11 -0700
Neal Frager <neal.frager at amd.com> wrote:

> If a user requests a u-boot binary in elf format,
> they may actually want the stripped u-boot.elf version.
> This patch provides the stripped u-boot.elf binary.
> 
> Signed-off-by: Neal Frager <neal.frager at amd.com>
> ---
> V1->V2:
>   - reduced scope to only 64-bit ARM arch platforms
>   - non-ARM platforms may not have a u-boot.elf by default
> ---
>  boot/uboot/uboot.mk | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/boot/uboot/uboot.mk b/boot/uboot/uboot.mk
> index 0439ec5e4b..61b3074163 100644
> --- a/boot/uboot/uboot.mk
> +++ b/boot/uboot/uboot.mk
> @@ -54,6 +54,9 @@ endif
>  
>  ifeq ($(BR2_TARGET_UBOOT_FORMAT_ELF),y)
>  UBOOT_BINS += u-boot
> +ifeq ($(BR2_aarch64),y)
> +UBOOT_BINS += u-boot.elf
> +endif

Is it really assured that all arm64 do build this file? And that
u-boot.elf is not useful for other architectures?

Looking at the U-Boot source code, it looks like this file is built if
CONFIG_REMAKE_ELF is enabled, which seems independent on the
architecture and happens for some non-arm64 defconfigs as well (e.g.
netgear_dgnd3700v2_ram_defconfig).

At first glance, it looks like we need (yet) another Kconfig knob in
Buildroot to manage this cleanly. Otherwise in
UBOOT_INSTALL_IMAGES_CMDS we might just install u-boot.elf if it is
present,skip it silently otherwise.

Not sure which solution is less appealing. :(

-- 
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com