priv-1.9-rc0-like branch for fpga-zynq and rocket-chip about fpga-zynq

[zhemao]

The priv-1.9-rc0 branches of spike and riscv-tools seem to have been deleted. We've made a lot of privileged ISA changes since them, so I'm not sure what to tell you. The priv-1.9 ISA will be in draft mode for a while. Maybe @aswaterman can comment on when we expect a stable ISA release.

[heshamelmatary]

I used the priv-1.9-rc0 from riscv-tools, and it checks out some hardcoded revisions rather than branches. Seems like a lot has changed (entry address, ABI and PTE format) diff priv-1.9. It's becoming a hurdle (especially for supervisor-level SW like OSes/bootloaders) to keep up with such changes.

I would suggest to have "stable" branches and/or revisions including the rocket chip, spike, riscv-fesvr (both for ARM and native) and pk as standard/reference implementations for each priv release.

[zhemao]

We will have stable releases of riscv-tools for stable privileged ISA releases. Priv-1.9 is not meant to be a stable release. There is a reason all of the ISA documents say "draft" on them. Priv-1.7 is the current stable privileged ISA, and the master branch of riscv-tools conforms to that spec.