While the list of rules may have been accurate when created, it now lacks some clarity in the face of isa-manual updates. Specifically: - there is no mention here of a distinction between regular 'Z' extensions which are "Additional Standard Extensions" and "Zxm" extensions which are "Standard Machine-Level Extensions" - there is also no explicit mention of where either should be sorted in the list - underscores are only required between two *multi-letter* extensions but the list of rules implies that this is required between a multi-letter extension and any other extension. IOW "rv64imafdzicsr_zifencei" is a valid string Attempt to clean up the list of rules, by adding information on the above & sprinkling in some white space for readability. Signed-off-by: Conor Dooley <conor.dooley@xxxxxxxxxxxxx> --- arch/riscv/kernel/cpu.c | 22 +++++++++++++++++----- 1 file changed, 17 insertions(+), 5 deletions(-) diff --git a/arch/riscv/kernel/cpu.c b/arch/riscv/kernel/cpu.c index 852ecccd8920..5e42c92a8456 100644 --- a/arch/riscv/kernel/cpu.c +++ b/arch/riscv/kernel/cpu.c @@ -120,20 +120,32 @@ device_initcall(riscv_cpuinfo_init); .uprop = #UPROP, \ .isa_ext_id = EXTID, \ } + /* * Here are the ordering rules of extension naming defined by RISC-V * specification : - * 1. All extensions should be separated from other multi-letter extensions - * by an underscore. + * + * 1. All multi-letter extensions should be separated from other multi-letter + * extensions by an underscore. + * * 2. The first letter following the 'Z' conventionally indicates the most * closely related alphabetical extension category, IMAFDQLCBKJTPVH. - * If multiple 'Z' extensions are named, they should be ordered first - * by category, then alphabetically within a category. + * 'Z' extensions should be sorted after single-letter extensions and before + * any higher-privileged extensions. + * If multiple 'Z' extensions are named, they should be ordered first by + * category, then alphabetically within a category. + * * 3. Standard supervisor-level extensions (starts with 'S') should be * listed after standard unprivileged extensions. If multiple * supervisor-level extensions are listed, they should be ordered * alphabetically. - * 4. Non-standard extensions (starts with 'X') must be listed after all + * + * 4 Standard machine-level extensions (starts with 'Zxm') should be + * listed after any lower-privileged, standard extensions. If multiple + * machine-level extensions are listed, they should be ordered + * alphabetically. + * + * 5. Non-standard extensions (starts with 'X') must be listed after all * standard extensions. They must be separated from other multi-letter * extensions by an underscore. */ -- 2.38.1
