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bmips: Build U-Boot into the XG6846 target

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It appears that the CFE boot loader found in the XG6846
cannot load kernels over a certain size, and the old
relocate hack is not working.

What to do? We can build a small U-Boot into the image,
make CFE boot that, place the kernel immediately after
U-Boot, and use U-Boot to boot the system instead.

The compiled u-boot.bin becomes around ~300KB and with
LZMA compression it will swiftly fit into 128KB, so
we use two 64KB erase blocks right after the CFE to
store an imagetag:ed U-Boot.

Reviewed-by: Paul Donald <newtwen+github@gmail.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
This commit is contained in:
Linus Walleij 2023-08-05 09:02:20 +02:00
parent f789454df1
commit 219018185e
3 changed files with 34 additions and 2 deletions
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3
target/linux/bmips/dts/bcm6328-inteno-xg6846.dts
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@ -117,9 +117,10 @@
};
partition@10000 {
compatible = "brcm,bcm963xx-imagetag";
compatible = "openwrt,uimage", "denx,uimage";
reg = <0x010000 0xfe0000>;
label = "firmware";
openwrt,offset = <0x30000>;
};
partition@ff0000 {

31
target/linux/bmips/image/Makefile
View File

@ -4,6 +4,7 @@ include $(TOPDIR)/rules.mk
include $(INCLUDE_DIR)/image.mk
KERNEL_LOADADDR := 0x80010000 # RAM start + 64K
UBOOT_ENTRY := 0x81c00000
LOADER_ENTRY := 0x81000000 # RAM start + 16M, for relocate
LZMA_TEXT_START := 0x82000000 # RAM start + 32M
@ -94,6 +95,21 @@ define Build/cfe-bin
$(CFE_EXTRAS) $(1)
endef
# Build a CFE image with just U-Boot
define Build/cfe-bin-uboot
cp $(STAGING_DIR_IMAGE)/$(DEVICE_NAME)-u-boot.bin $@
$(call Build/lzma)
mv $@ $@.uboot.lzma
echo "dummy" > $@.dummyfs
$(STAGING_DIR_HOST)/bin/imagetag -i $@.uboot.lzma -f $@.dummyfs \
--output $@ --boardid $(CFE_BOARD_ID) --chipid $(CHIP_ID) \
--entry $(UBOOT_ENTRY) --load-addr $(UBOOT_ENTRY) \
--info1 "$(call ModelNameLimit16,$(DEVICE_NAME))" \
$(CFE_EXTRAS) $(1)
rm $@.uboot.lzma
rm $@.dummyfs
endef
define Build/cfe-jffs2
$(STAGING_DIR_HOST)/bin/mkfs.jffs2 \
--big-endian \
@ -284,6 +300,21 @@ define Device/bcm63xx-cfe-legacy
KERNEL := kernel-bin | append-dtb | relocate-kernel | lzma-cfe
endef
# CFE images with U-Boot in front of the kernel, these will execute
# U-Boot instead of the kernel and U-Boot will then proceed to load
# the kernel. The reason to do this is that CFE is sometimes unable to
# load big kernels even with the lzma loader tricks.
define Device/bcm63xx-cfe-uboot
$(Device/bcm63xx-cfe)
KERNEL := kernel-bin | append-dtb | lzma | uImage lzma
IMAGE/cfe.bin := cfe-bin-uboot | pad-to $$$$$$$$(($$(BLOCKSIZE))) | \
append-kernel | pad-to $$$$$$$$(($$(BLOCKSIZE))) | \
append-rootfs $$$$(if $$$$(FLASH_MB),--pad $$$$(shell expr $$$$(FLASH_MB) / 2))
IMAGE/sysupgrade.bin := cfe-bin-uboot | pad-to $$$$$$$$(($$(BLOCKSIZE))) | \
append-kernel | pad-to $$$$$$$$(($$(BLOCKSIZE))) | \
append-rootfs | append-metadata
endef
# CFE expects a single JFFS2 partition with cferam and kernel. However,
# it's possible to fool CFE into properly loading both cferam and kernel
# from two different JFFS2 partitions by adding dummy files (see

2
target/linux/bmips/image/bcm6328.mk
View File

@ -52,7 +52,7 @@ endef
TARGET_DEVICES += innacomm_w3400v6
define Device/inteno_xg6846
$(Device/bcm63xx-cfe-legacy)
$(Device/bcm63xx-cfe-uboot)
DEVICE_VENDOR := Inteno
DEVICE_MODEL := XG6846
CHIP_ID := 6328