Why swap is disabled on imagebuilder-ath79-tiny kernels

[oferreiro]

I'm trying generate an image to my old router tplink_tl-wr841-v7.
make image PROFILE=tplink_tl-wr841-v7 PACKAGES="-opkg kmod-zram zram-swap"

But I can not use zram:

swapon: /dev/zram0: Function not implemented


in last snapshot:
openwrt-imagebuilder-ath79-tiny.Linux-x86_64/build_dir/target-mips_24kc_musl/linux-ath79_tiny/linux-4.19.108/.config

or:
openwrt-imagebuilder-19.07.2-ath79-tiny.Linux-x86_64/build_dir/target-mips_24kc_musl/linux-ath79_tiny/linux-4.14.171/.config

# CONFIG_SWAP is not set

in:
openwrt-imagebuilder-18.06.8-ar71xx-tiny.Linux-x86_64/build_dir/target-mips_24kc_musl/linux-ar71xx_tiny/linux-4.9.214/.config

CONFIG_SWAP=y

Is there any reason to keep it disabled on last imagebuilders?
This router have only 32Mb ram. I think it is a good idea use zram. But I can not mount zram without swap support.

Thanks.

[slh]

Because it's one of the things that do get disabled (swap support is rather large and does depend on further, large, infrastructure to support block devices, filesystems et al) for targets that define small_flash and thereby select SMALL_FLASH, in order to reduce the image size. If you do want to change this, the existing binaries consumed by imagebuilder can't accomplish this, you'll have change this on the source level and build from source.