One thing that worries me about RISC-V is how much encoding space for (major) opcodes they already used up. There are 7 bits to encode the opcodes. Of those 12

One thing that worries me about RISC-V is how much encoding space for (major) opcodes they already used up. There are 7 bits to encode the opcodes. Of those 128 possible values, 3/4 are used for 16-bit compressed/thumb instructions. The remaining 32 values are allocated as follows: * 4 are for custom instructions * 4 are for larger than 32-bit instructions * 21 are already used * 3 are reserved for future use While there is some space for minor opcodes (encoded via func3/func7) inside of the already allocated major opcodes, this allocation seems overly generous to me considering how young the instruction set still is. I would have felt far more comfortable with compressed instructions only taking 1/2 instead of 3/4 of the total available space.