[0/2] hw/riscv/virt.c: change default CPU to 'max'

Message

Daniel Henrique Barboza April 4, 2025, 3:27 p.m. UTC

Hi,

The 'rv64' CPU, the default CPU for the 'virt' machine, is a strange
CPU. It is a collection of extensions that were enabled/disabled as
extensions were being added in TCG, and in the end we ended up with a
CPU that we can't say exactly what it does.

This is further aggravated by the distros move to support the RVA23
profile. Patch 2 has more details, but long story short: distros uses
the 'virt' machine, and they'll start building on top of RVA23, and rv64
does not have RVA23 support. In short, distros will start to break in
the default 'virt' CPU.

Changing the default CPU to 'max' will not cause (intentional) user
regressions: if the software runs in rv64 it will run in 'max' too given
that we're adding more extensions as default instead of removing them.
In my opinion this might be enough to avoid a deprecation cycle and we
can do the change for 10.1.

And yeah, patch 2 mentions the already old trope "and ARM does the
same". This is intentional: I want RISC-V code and usability to be as
close as possible to ARM and other archs to promote a more homogeneous
experience when developing and using QEMU.


Daniel Henrique Barboza (2):
  target/riscv/tcg: make 'max' cpu rva23s64 compliant
  hw/riscv/virt.c: change default CPU to 'max'

 hw/riscv/virt.c            | 2 +-
 target/riscv/tcg/tcg-cpu.c | 2 ++
 2 files changed, 3 insertions(+), 1 deletion(-)