[openwrt/openwrt] ar71xx: Ubiquiti Airmax M: add relocate-kernel to invalidate cache

[LEDE Commits]

neoraider pushed a commit to openwrt/openwrt.git, branch master:
https://git.lede-project.org/d168c2cf81ab4218df4c9b43e4483b6340bcfc9d

commit d168c2cf81ab4218df4c9b43e4483b6340bcfc9d
Author: Matthias Schiffer <mschiffer at universe-factory.net>
AuthorDate: Thu Apr 26 20:04:48 2018 +0200

    ar71xx: Ubiquiti Airmax M: add relocate-kernel to invalidate cache
    
    Some Ubiquiti U-boot versions, in particular the "U-Boot 1.1.4.2-s956
    (Jun 10 2015 - 10:54:50)" found with AirOS 5.6, do not correctly flush the
    caches for the whole kernel address range after decompressing the kernel
    image, leading to hard to debug boot failures, depending on kernel version
    and configuration.
    
    As a workaround, prepend the relocate-kernels loader, which will invalidate
    the caches after moving the kernel to the correct load address.
    
    Reported-by: Andreas Ziegler <dev at andreas-ziegler.de>
    Signed-off-by: Matthias Schiffer <mschiffer at universe-factory.net>
---
 target/linux/ar71xx/image/generic-ubnt.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/linux/ar71xx/image/generic-ubnt.mk b/target/linux/ar71xx/image/generic-ubnt.mk
index d5e3aa5..07c0295 100644
--- a/target/linux/ar71xx/image/generic-ubnt.mk
+++ b/target/linux/ar71xx/image/generic-ubnt.mk
@@ -52,6 +52,7 @@ define Device/ubnt-xm
   DEVICE_PACKAGES += kmod-usb-ohci
   UBNT_TYPE := XM
   UBNT_CHIP := ar7240
+  KERNEL := kernel-bin | patch-cmdline | relocate-kernel | lzma | uImage lzma
 endef
 
 define Device/ubnt-xw