Whats point of padjffs2?

For Developers
1

Hello, while analyzing my logs of the building my oldie-goldie D-Link DIR620 revA I found:

/home/ice/external/openwrt_build/under_env/openwrt_22_series_for_dlink620/staging_dir/host/bin/padjffs2 /home/ice/external/openwrt_build/under_env/openwrt_22_series_for_dlink620/build_dir/target-mipsel_24kc_musl/linux-ramips_rt305x/tmp/openwrt-ramips-rt305x-dlink_dir-620-a1-squashfs-sysupgrade.bin 4 8 16 64 128 256

padding image to 0064f000

padding image to 00650000

padding image to 00660000

padding image to 00680000

It is strange for me as seems prepare_generic_squashfs macro is supposed to work
for some bcm routers only. Why do I see this? It doesn't actually harm my system and even no over space is used inside actual image. But my goal is to understand size of sysupgrade output. And , probably, a bit less RAM I would need during install.

2

the rule was invoked bacause both
sysupgrade_bin and IMAGE/sysupgrade.bin have
pad-rootfs stage enabled by default. Will turn it off and see what will happen.

As far as I understand my device is bare mtd one, no jffs2 present here. The only padding I need is accordingly to erase block of mtd.

3

Now i seem to understand what's going on. This is the way how upgrade formats overlay file system. Via given padding. Will try to do it dynamically from script instead of padding. I don't like padding. It takes precious RAM

4

Rest of answers i found here:

5

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