the 32 bit variants turn out to be severely under pressure, cf chacha20
needing 3D svshape2.
please have bits that are specifically reserved for enabling future regfile extensions, last time setvl had that but you ended up using it for something else, i was eventually ok with that because i figured we could cram those extension bits in the prefix of sv.setvl
if you can reserve 3 bits at minimum, preferably 5-8 bits, that should be good. we'd need 3 bits for a mode and the rest for immediate extension to support larger VL/MAXVL.