I noticed there's a CONFIG_TARGET_SQUASHFS_BLOCK_SIZE parameter that controls it, but I'm sure where it gets its default value from since there doesn't seem to be any other references to that variable (see here).
I can set it by editing include/image.mk manually, but how I can set it via make with the image builder?
I haven't checked it but my strong hunch is that you can't set it in imagebuilder. Imagebuilder only cooks together already compiled packages, so any compilation option is out of scope. The packages and kernel have already been compiled with the default options.
Ah okay, too bad though because it's a handy option to set when you run out of space and it seems appropriate for the image builder since it generates the squashfs. But editing the file manually seems to work.
I'm still curious which package sets the default value for CONFIG_TARGET_SQUASHFS_BLOCK_SIZE. Any ideas?
The option is coming from https://github.com/lede-project/source/blob/master/config/Config-images.in