It would be nice to have TMS (Test Monitor System) onboard. Some big vendors have it on their systems for ages. Pros: a) Test for DRAM b) Test for Media (HDD, CF, SD, ..) connected to the host c) Test for Peripherals Cons: a) size. may not fit into 1/2/4 Mbit.
TMS is a regular payload, access is done via RS232 (or USB in future), the same way as we all see printk messages nowdays. However, it's not yet clear to me is it possible to have multiple payloads at once and how to choose between them. Where to store boot options (CMOS is a way too small for it).
Another concept to store big payloads which can't be stored in flash (even 16 Mbit is not enough) is to have dedicated partition. On booting media. With FAT16 or use a very simple FS to avoid licensing problems (no journaling features required).
Pros: a) bigger and more payload sources at once from one place b) possibility to have several linuxbios images to be flashed back in case of emergency Cons: a) need to prepare boot media, like SATA/IDE device, to have dedicated partition b) need to add support lines for FS on dedicated FS (however, I see FILO can boot ext2 partition, hope this one will be enough).
Comments are welcome.