Hi,
when I'm having trouble with lzma what I do is not build a payload, and run the ramstage uncompressed, and at least make sure that works.
I think this is your real problem, as you say.
Trying CBFS ramstage loader. CBFS: loading stage fallback/ramstage @ 0x100000 (151600 bytes), entry @ 0x100000 CBFS: tried to decompress 43540 bytes with algorithm #1,but that algorithm id is unsupported. Ramstage was not loaded!
This is really weird. But I don't think you should go one step further until you see why this is happening, because it points to other bigger problems.
BTW, when you omitted the vga bios, did you rebuild seabios to not expect vga to be present?
I don't think the issue is the lzma compression does not work. Somehow the config step is broken, and if that variable is not set right, others may not be set right either. The integrity of your build is questionable.
When's the last time we had a success with EPIA-M? I just don't recall, anyone know?
ron