[openwrt/openwrt] ramips: mt7620: add kernel size for Jboot devices

[LEDE Commits]

adrian pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/e1d8a14cd0a9f8844f9ebb8ca220780b0ce5d6db

commit e1d8a14cd0a9f8844f9ebb8ca220780b0ce5d6db
Author: Pawel Dembicki <paweldembicki at gmail.com>
AuthorDate: Wed Jun 9 12:22:39 2021 +0200

    ramips: mt7620: add kernel size for Jboot devices
    
    Since few months multiple users reported problems with various JBoot
    devices. [0][1][2][3] All of them was bricked.
    
    On my Lava LR-25G001 it freezes with current snapshot:
    
    CDW57CAM_003 Jboot B695
    Giga Switch AR8327 init
    AR8327/AR8337 id   ==> 0x1302
    JRecovery Version R1.2 2014/04/01 18:25
    SPI FLASH: MX25l12805d 16M
    .
    .
    (freeze)
    
    The kernel size is >2048k.
    
    I built current master with minimal config and it boots well:
    
    CDW57CAM_003 Jboot B695
    Giga Switch AR8327 init
    AR8327/AR8337 id   ==> 0x1302
    JRecovery Version R1.2 2014/04/01 18:25
    SPI FLASH: MX25l12805d 16M
    .
    ...........................
    Starting kernel @80000000...
    [    0.000000] Linux version 5.4.124
    
    Kernel size is <2048k.
    
    Jboot bootloader isn't open source, so it's impossible to find
    solution in code. It looks, that some buffer for kernel have 2MB size.
    
    To avoid bricked devices, this commit introduces 2048k limit kernel
    size for all jboot routers.
    
    [0] https://bugs.openwrt.org/index.php?do=details&task_id=3539
    [1] https://eko.one.pl/forum/viewtopic.php?pid=254344
    [2] https://eko.one.pl/forum/viewtopic.php?id=20930
    [3] https://eko.one.pl/forum/viewtopic.php?pid=241376#p241376
    
    Signed-off-by: Pawel Dembicki <paweldembicki at gmail.com>
    [remove Fixes:]
    Signed-off-by: Adrian Schmutzler <freifunk at adrianschmutzler.de>
---
 target/linux/ramips/image/mt7620.mk | 1 +
 1 file changed, 1 insertion(+)

diff --git a/target/linux/ramips/image/mt7620.mk b/target/linux/ramips/image/mt7620.mk
index 8f5d354e33..e56e96d347 100644
--- a/target/linux/ramips/image/mt7620.mk
+++ b/target/linux/ramips/image/mt7620.mk
@@ -62,6 +62,7 @@ TARGET_DEVICES += alfa-network_tube-e4g
 define Device/amit_jboot
   DLINK_IMAGE_OFFSET := 0x10000
   KERNEL := $(KERNEL_DTB)
+  KERNEL_SIZE := 2048k
   IMAGES += factory.bin
   IMAGE/sysupgrade.bin := mkdlinkfw | pad-rootfs | append-metadata
   IMAGE/factory.bin := mkdlinkfw | pad-rootfs | mkdlinkfw-factory