[openwrt/openwrt] at91: sama7: fix racy SD card image generation

[LEDE Commits]

ynezz pushed a commit to openwrt/openwrt.git, branch openwrt-22.03:
https://git.openwrt.org/52564e65d592cc691f7e93eeaa839785b5363e22

commit 52564e65d592cc691f7e93eeaa839785b5363e22
Author: Petr Štetiar <ynezz at true.cz>
AuthorDate: Tue Jan 3 12:44:51 2023 +0100

    at91: sama7: fix racy SD card image generation
    
    We've few low spec (make -j3) build workers attached to the 22.03
    buildbot instance which from time to time exhibit following build
    failure during image generation:
    
     + dd bs=512 if=root.ext4 of=openwrt-22.03-snapshot-r20028-43d71ad93e-at91-sama7-microchip_sama7g5-ek-ext4-sdcard.img.gz.img seek=135168 conv=notrunc
     dd: failed to open 'root.ext4': No such file or directory
    
    Thats likely due to the fact, that on buildbots we've
    `TARGET_PER_DEVICE_ROOTFS=y` which produces differently named filesystem
    image in the SD card image target dependency chain:
    
     make_ext4fs -L rootfs ... root.ext4+pkg=68b329da
    
    and that hardcoded root.ext4 becomes available from other target in the
    later stages. So lets fix this issue by using IMAGE_ROOTFS Make variable
    which should contain proper path to the root filesystem image.
    
    Signed-off-by: Petr Štetiar <ynezz at true.cz>
    (cherry picked from commit 5c3679e39b615ff29c9315f810e8e15775cc2d01)
---
 target/linux/at91/image/sama7.mk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/target/linux/at91/image/sama7.mk b/target/linux/at91/image/sama7.mk
index bf1704dfb3..8d6f67d80e 100644
--- a/target/linux/at91/image/sama7.mk
+++ b/target/linux/at91/image/sama7.mk
@@ -35,7 +35,7 @@ define Build/at91-sdcard
   ./gen_at91_sdcard_img.sh \
 	$@.img \
 	$@.boot \
-	$(KDIR)/root.ext4 \
+	$(IMAGE_ROOTFS) \
 	$(AT91_SD_BOOT_PARTSIZE) \
 	$(CONFIG_TARGET_ROOTFS_PARTSIZE)