Re: [PATCH] dfu: Make the DFU_WRITE_ALT symbol available outside of DFU

[Mattijs Korpershoek <mkorpershoek@kernel.org>]

Hi Tom,

On Thu, Mar 12, 2026 at 16:58, Tom Rini <trini@konsulko.com> wrote:

> On Thu, Mar 12, 2026 at 10:10:06AM +0100, Mattijs Korpershoek wrote:
>> Hi Tom,
>>
>> Thank you for the patch.
>>
>> On Tue, Mar 10, 2026 at 10:26, Tom Rini <trini@konsulko.com> wrote:
>>
>> > The DFU_WRITE_ALT symbol is used both directly and indirectly (via
>> > UPDATE_COMMON) for EFI capsule updates (FIT or raw), but does not depend
>> > on DFU itself. Move this symbol outside of "if DFU" to remove a Kconfig
>> > dependency problem.
>>
>> Looking at drivers/dfu/dfu_alt.c both dfu_write_by_name() and
>> dfu_write_by_alt() seem to rely on functions from drivers/dfu/dfu.c such
>> as dfu_init_env_entities(), dfu_get_entity() and more.
>>
>> Looking at UPDATE_COMMON, I see:
>> config UPDATE_COMMON
>> 	bool
>> 	select DFU_WRITE_ALT
>> 	imply CMD_TFTPBOOT
>>
>> And if we check the code in common/update.c, we can see that
>> dfu_write_by_name() is called.
>>
>> So fit_update() calls
>>    dfu_write_by_name() which calls
>>        dfu_init_env_entities() which might no longer be defined when
>>                                applying this patch.
>>
>> I'm not sure how is this supposed to work. Do we have to stub
>> dfu_init_env_entities() ?
>
> So, to me the challenge is that DFU_TFTP, UPDATE_FIT and UPDATE_TFTP all
> are the three users of UPDATE_COMMON and so DFU_WRITE_ALT. The first two
> depend on DFU, but the latter does not. And there's nothing in-tree
> using it, either (but it does compile I believe, or allyesconfig would
> have failed).

I see, thank you for explaining. I've done some testing on sandbox with
the following diff:

diff --git a/configs/sandbox_defconfig b/configs/sandbox_defconfig
index 280f9c9cfe77..5bc114bad064 100644
--- a/configs/sandbox_defconfig
+++ b/configs/sandbox_defconfig
@@ -16,9 +16,6 @@ CONFIG_EFI_SECURE_BOOT=y
 CONFIG_EFI_RT_VOLATILE_STORE=y
 CONFIG_EFI_RUNTIME_UPDATE_CAPSULE=y
 CONFIG_EFI_CAPSULE_ON_DISK=y
-CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y
-CONFIG_EFI_CAPSULE_AUTHENTICATE=y
-CONFIG_EFI_CAPSULE_CRT_FILE="board/sandbox/capsule_pub_key_good.crt"
 CONFIG_BUTTON_CMD=y
 CONFIG_FIT=y
 CONFIG_FIT_CIPHER=y
@@ -50,6 +47,7 @@ CONFIG_LOGF_FUNC=y
 CONFIG_DISPLAY_BOARDINFO_LATE=y
 # CONFIG_BOARD_INIT is not set
 CONFIG_STACKPROTECTOR=y
+CONFIG_UPDATE_TFTP=y
 CONFIG_ANDROID_AB=y
 CONFIG_CMD_CPU=y
 CONFIG_CMD_UFETCH=y
@@ -201,7 +199,6 @@ CONFIG_AES_SOFTWARE=y
 CONFIG_DM_DEMO=y
 CONFIG_DM_DEMO_SIMPLE=y
 CONFIG_DM_DEMO_SHAPE=y
-CONFIG_DFU_SF=y
 CONFIG_DMA=y
 CONFIG_DMA_CHANNELS=y
 CONFIG_SANDBOX_DMA=y
@@ -362,7 +359,6 @@ CONFIG_CONSOLE_ROTATION=y
 CONFIG_CONSOLE_TRUETYPE=y
 CONFIG_CONSOLE_TRUETYPE_CANTORAONE=y
 CONFIG_I2C_EDID=y
-CONFIG_VIDEO_SANDBOX_SDL=y
 CONFIG_VIDEO_BRIDGE=y
 CONFIG_VIDEO_BRIDGE_LVDS_CODEC=y
 CONFIG_VIDEO_DSI_HOST_SANDBOX=y

We indeed have:

$ grep -e CONFIG_DFU -e DFU_TFTP -e UPDATE_FIT -e UPDATE_TFTP .config
CONFIG_UPDATE_TFTP=y
CONFIG_UPDATE_TFTP_CNT_MAX=0
CONFIG_UPDATE_TFTP_MSEC_MAX=100
CONFIG_DFU_WRITE_ALT=y

Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>

>
> --
> Tom