I was at the last day of the RISC-V summit last week and spent half the day thinking about what would be the coolest uses for the $3 DUO 64MB.
At some point I just looked into random stuff and found someone has re-activated AXFS - a very cool filesystem for running the OS directly from flash.
XiP stands for “eXecute in Place”, meaning libraries and binaries on flash are mapped into memory and can be executed without loading them. That saves a lot of RAM and also sometimes more than that.
The theoretically best filesystem for that purpose is AXFS which has never gotten massive adoption but is working and runs circles around i.e. JFFS2 and also has more capabilities than ‘UbiFS’ (a later alternative for JFFS)
Check it out:
tl;dr:
- AXFS works on RISC-V
- OS runs from Flash, needs no RAM
- Faster load times
- Unclear if it needs to be QSPI flash only or normal NAND (!= NOR) works
- Kernel 5.10 is too low, 5.11 is already OK
- Author has a 5.10 patch set that can be requested.
- SPI flash modules are $3-5 also, but best would be to get it going with an SD card.