On 24/11/2022 17:34, Samuel Ortiz wrote: > On Thu, Nov 24, 2022 at 05:20:37PM +0000, Conor Dooley wrote: >> On 24/11/2022 17:12, Samuel Ortiz wrote: >>> [You don't often get email from sameo@xxxxxxxxxxxx. Learn why this is important at https://aka.ms/LearnAboutSenderIdentification ] >>> >>> EXTERNAL EMAIL: Do not click links or open attachments unless you know the content is safe >>> >>> On Thu, Nov 24, 2022 at 11:55:01AM +0000, Conor Dooley wrote: >>>> On Thu, Nov 24, 2022 at 11:47:30AM +0100, Samuel Ortiz wrote: >>>> >>>>> Patch #1 is definitely needed regardless of which interface we pick for >>>>> exposing the ISA strings to userspace. >>>> >>>> I took another look at #1, and I feel more confused about what >>>> constitutes canonical order than I did before! If you know better than >>>> I, and you probably do since you're interested in these 6 month old >>>> patches, some insight would be appreciated! >>> >>> Assuming we don't go with hwcap, I dont think the order of the >>> riscv_isa_ext_id enum matters that much? >> >> The chief put it in canonical order so that's good enough for me! >> >>> >>> iiuc we're building the cpuinfo string from the riscv_isa_ext_data >>> array, and I think the current code is incorrect: >>> >>> static struct riscv_isa_ext_data isa_ext_arr[] = { >>> __RISCV_ISA_EXT_DATA(sscofpmf, RISCV_ISA_EXT_SSCOFPMF), >>> __RISCV_ISA_EXT_DATA(sstc, RISCV_ISA_EXT_SSTC), >>> __RISCV_ISA_EXT_DATA(svinval, RISCV_ISA_EXT_SVINVAL), >>> __RISCV_ISA_EXT_DATA(svpbmt, RISCV_ISA_EXT_SVPBMT), >>> __RISCV_ISA_EXT_DATA(zicbom, RISCV_ISA_EXT_ZICBOM), >>> __RISCV_ISA_EXT_DATA(zihintpause, RISCV_ISA_EXT_ZIHINTPAUSE), >>> __RISCV_ISA_EXT_DATA("", RISCV_ISA_EXT_MAX), >>> }; >>> >>> zicbom and zihintpause should come before supervisor level extensions. >>> I'm going to send a patch for that. >> >> idk, Palmer explicitly re-ordered this: >> https://lore.kernel.org/linux-riscv/20220920204518.10988-1-palmer@xxxxxxxxxxxx/ >> >> By my reading of the isa manual, what Palmer did is correct as >> those are not "Additional Standard Extensions". /shrug > > Hmm, by their name (Z[a-b]+) they are Additional Standard Extensions. > What am I missing? Right, and this is where I get confused. Zam and Ztso *are* Additional Standard Extensions, I think we can agree on that one? For those extensions: \chapter{``Ztso'' Standard Extension for Total Store Ordering, v0.1} \chapter{``Zam'' Standard Extension for Misaligned Atomics, v0.1} They're also called out specifically in the table: https://github.com/riscv/riscv-isa-manual/blob/master/src/naming.tex#L147 For Zihintpause however: \chapter{``Zihintpause'' Pause Hint, Version 2.0} See what I mean? I looked at the specs for the bitmanip stuff and for crypto, which both never mention being standard. That table has the caption: > The table also defines the canonical order in which extension names > must appear in the name string, with top-to-bottom in table > indicating first-to-last in the name string. It only calls out Zicsr, Zifencei, Zam and Ztso are being permitted before Sdef, but as I said I am not a specs person, so perhaps some of the extensions in question are intended to go there but have not yet been merged into the isa manual doc. Zihintpause *is* in the isa manual though but not specifically called out. Anyways, hopefully that at least helps with my line of thinking! Conor.
