[PATCH 0/3] riscv: Deprecate userspace vector control interfaces

[Samuel Holland]

After several discussions within RISE and at Linux Plumbers 2026,
consensus is that these controls create more trouble than benefits, and
should not be used. glibc will not support using them[1], and we don't
know of other users. There is also no plan to add similar controls for
future extensions that add register state (e.g. matrix).

Let's deprecate them now, hiding them behind a default-disabled Kconfig
option so distributions can avoid exposing them. Hopefully they will not
pick up any new users, and we can remove them in the future.

[1]: https://inbox.sourceware.org/libc-alpha/20261006134856.42295-1-palmer@xxxxxxxxxxx/


Samuel Holland (3):
  riscv: Drop CONFIG_RISCV_ISA_V_DEFAULT_ENABLE
  riscv: Deprecate vector state prctl/sysctl
  RISC-V: KVM: Decouple vector prctl state from VM ISA

 arch/riscv/Kconfig                 | 13 ++++++-------
 arch/riscv/include/asm/processor.h |  4 +++-
 arch/riscv/include/asm/vector.h    | 16 ++++++++++++----
 arch/riscv/kernel/vector.c         | 12 +++++++++++-
 arch/riscv/kvm/isa.c               |  3 ---
 5 files changed, 32 insertions(+), 16 deletions(-)

-- 
2.52.0

base-commit: a90ee4305c4a5df72c11b31dacfdc76e00fcf78a
branch: up/deprecate-prctl