[OpenWrt-Devel] Regarding change "ath79: move lzma-loader to the end of available RAM"

[Christopher Hill]

Hello,

I was looking at this recent change [1] to move the lzma-loader in
ath79, which has comment:


"In certain cases, the uncompressed initramfs image will overwrite
the lzma-loader, which is currently only 10 MB away from kernel image
start. To prevent this, change LZMA_TEXT_START to 24 MB, so loader
and compressed image have 8 MB at the end of RAM and uncompressed
image has 24 MB available."


I bring this up as I'm (slowly) porting a Mikrotik rb493g for ath79 [2]
and I believe I need additional change in this area.

Looking at the older ar71xx image
"openwrt-19.07.0-ar71xx-mikrotik-vmlinux-initramfs-lzma.elf" binwalk
shows "LZMA compressed data, properties: 0x6D, dictionary size: 8388608
bytes, uncompressed size: 7543556 bytes" and this boots fine.

Building an ath79 image from latest git sources and running binwalk
shows "LZMA compressed data, properties: 0x6D, dictionary size: 8388608
bytes, uncompressed size: 12491705 bytes"

i.e. instead of a 7MB image, it's now a 12MB image.

I was thinking the lzma-loader change would mean this is OK, however it
will not boot.

So...

I added configuration "default TARGET_INITRAMFS_COMPRESSION_LZMA if
TARGET_ath79" and this reduces the generated image to "uncompressed
size: 8396454 bytes"

i.e. an 8MB image, and this will boot.


Perhaps this is an issue with RouterBOOT booter 6.41, or the rb4xx
series boards and this new location?


Thanks,
Chris


N.B. If I add LuCI to this smaller image it grows to "uncompressed size:
8752277 bytes" and this will also not boot.



[1]
https://github.com/openwrt/openwrt/commit/071a6372762d289b2fa5a8d1a138eff944c93c9e

[2]
https://github.com/ch6574/openwrt/commit/deeb9203f73a396ddca89aa8b2ce69c47974afe5

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