[nrf noup] linker: fix incorrect check

squash! [nrf noup] tree-wide: support NCS Partition Manager (PM)

When both b0 (CONFIG_SECURE_BOOT) and MCUboot
(CONFIG_BOOTLOADER_MCUBOOT) is enabled we need some symbols to be
set correctly in the MCUboot image depending on if it is being
built as a variant image or not.

Specifically, if MCUboot is built as a variant image, this indicates
that it will be located in the S1 slot (b0 terminology).

When MCUboot is located in the S1 slot in needs to point to the
slot ID of slot S0 as the primary slot for image 1. This so that
any update of image 1 (which is an update of MCUboot itself) is
stored in slot S0.

The problem with the check was that it would not be true for
the MCUboot variant image. This because CONFIG_SECURE_BOOT
is only set for the top level image, and not MCUboot which is
typically built as a child image.

Hence, the variant build of MCUboot would not have the correct
value for '_image_1_primary_slot_id' as it would point to
'PM_S1_ID' instead.

This resulted in MCUboot located in S1 slot not being able to
load a new MCUboot image into slot S0.

Ref: NCSDK-15503

Signed-off-by: Håkon Øye Amundsen <[email protected]>

Author: hakonfam

include/zephyr/arch/arm/aarch32/cortex_m/scripts/linker.ld

@@ -31,7 +31,7 @@
 
 #include <pm_config.h>
 
-#if CONFIG_NCS_IS_VARIANT_IMAGE && CONFIG_SECURE_BOOT
+#if CONFIG_NCS_IS_VARIANT_IMAGE && defined(PM_S0_ID)
 /* We are linking against S1, create symbol containing the flash ID of S0.
  * This is used when writing code operating on the "other" slot.
  */