RISC-V: T-Head vector handling
From: Heiko Stuebner <heiko.stuebner@...> Date: Fri, 23 Jun 2023 01:06:10 +0200
As is widely known the T-Head C9xx cores used for example in the Allwinner D1 implement an older non-ratified variant of the vector spec. While userspace will probably have a lot more problems implementing support for both, on the kernel side the needed changes are actually somewhat small'ish and can be handled via alternatives somewhat nicely. With this patchset I could run the same userspace program (picked from some riscv-vector-test repository) that does some vector additions on both qemu and a d1-nezha board. On both platforms it ran sucessfully and even produced the same results. As can be seen in the todo list, there are 2 places where the changed SR_VS location still needs to be handled in the next revision (assembly + ALTERNATIVES + constants + probably stringify resulted in some grey hair so far already) ToDo: - follow along with the base vector patchset - handle SR_VS access in _save_context and _secondary_start_sbi changes since v1: - rebase on top of the merged vector patchset - add separate patch for "has_vector()" variable - a number of cleanups - a comment that T-Head cores do not seem to implement the vxsat and vxrm fields in the fcsr register Heiko Stuebner (3): RISC-V: define the elements of the VCSR vector CSR RISC-V: move vector-available status into a dedicated variable RISC-V: add T-Head vector errata handling arch/riscv/Kconfig.errata | 13 +++ arch/riscv/errata/thead/errata.c | 32 ++++++ arch/riscv/include/asm/csr.h | 29 +++++- arch/riscv/include/asm/errata_list.h | 45 ++++++++- arch/riscv/include/asm/vector.h | 144 +++++++++++++++++++++++++-- arch/riscv/kernel/setup.c | 6 ++ arch/riscv/kernel/vector.c | 10 +- 7 files changed, 261 insertions(+), 18 deletions(-) -- 2.39.2
Patches in this set
- [0001] RISC-V: define the elements of the VCSR vector CSR (raw)
- [0002] RISC-V: move vector-available status into a dedicated (raw)
- [0003] RISC-V: add T-Head vector errata handling (raw)
Statistics
- 3 individual patches
- 261 lines added
- 18 lines removed