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NixOS RISC-V

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NixOS on RISC-V https://wiki.nixos.org/wiki/RISC-V https://pad.lassul.us/NixOS-riscv64-linux https://github.com/orgs/NixOS/teams/risc-v68 Servers

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4 Apr 2024
@skeuchel:matrix.orgSteven Keuchel
In reply to @thefossguy:matrix.org

Yeah, the multi-core interconnects are only present to connect the cores, not much more. i.e. not how 64-cores are interconnected on threadrippers/eypcs;

So here, qemu-emulation on x86 will be faster tbh

Most of the stuff I compile is quicker on the pioneer than user-mode emulations, so there's still something GHC-specific to it. Compiling w/o ilbnuma? Larger caches on x86? More "symbolic computations" in comparison to gcc?
12:57:44
@thefossguy:matrix.orgPratham Patel (you can mention me)There's obviously a lot of moving parts to this :)12:58:43
@thefossguy:matrix.orgPratham Patel (you can mention me)What I meant to say was, you're not actually using all 64-cores on the pioneer "efficiently" because the interconnects aren't well. It's a first gen product. Impressive that they could even pull it off, a first gen product nonetheless.12:59:42
@alex:tunstall.xyzAlex
In reply to @shalokshalom:kde.org
Hugs is even older than Eta, so I doubt very much it can compile any modern Haskell code at all?
It doesn't need to. It only needs to be able to interpret an old version of GHC, then the build can work its way up to a modern GHC.
13:43:26
@shalokshalom:kde.org@shalokshalom:kde.org Yeah, true. 14:03:45
@shalokshalom:kde.org@shalokshalom:kde.org Well then, Eta might be a choice. It has a native Haskell compiler for 7 and even some features of 8, probably better than Hugs 🤷 14:05:07
@rtunreal:c-base.orgrtunreal joined the room.15:23:24
@jopejoe1:matrix.orgjopejoe1 (4094@epvpn) joined the room.16:22:35
@hive:the-apothecary.clubDr. WormRedacted or Malformed Event18:06:30
@hive:the-apothecary.clubDr. Wormsorry not what i meant to post18:06:52
@hive:the-apothecary.clubDr. Wormi finally got a build failure that was just tests18:07:10
@hive:the-apothecary.clubDr. Wormthis is going to make things difficult,,,18:07:19
@hive:the-apothecary.clubDr. Wormcatch2-3.5.2-riscv64-linux18:07:20
@sorear:matrix.orgsorear

the C910 has two classes of issues:

  1. non-standard features for things that eventually became standard, i.e. RVV 0.7.1, MAEE instead of Svpbmt (needed for PCIe because Intel didn't distinguish BARs by memory type, irrelevant otherwise), T-Head performance counters, etc. None of this affects software that doesn't opt in to using the pre-standard feature, and none of it is morally different from any other non-standard extension, which are likely to be ubiquitous
  2. ordinary bugs - unreasonably slow contended memory access without fences, wrong decoding of noncanonical fences, wrong FP underflow flag - there is no reason to believe that future, more complicated cores will have fewer total bugs, even if they fix the current bugs, and also no evidence that the C910's crop of bugs can cause successful builds with miscompilations
18:24:49
@sorear:matrix.orgsorearI can't imagine a consistent standard which would (a) rule out the use of the C910 for non-test builds (b) not rule out every other piece of hardware which exists in the past and future for the same reason18:25:50
@thefossguy:matrix.orgPratham Patel (you can mention me)The SiFive J74 cores in the Unmatched and the VF2 are pretty spec compliant AFAIK18:30:07
@sorear:matrix.orgsorearare those the ones that can't correctly handle a sfence instruction with a nonzero virtual address and get the trap PC wrong when you jump to a negative noncanonical VA?18:32:03
@sorear:matrix.orgsorearsifive is better at communicating errata in english, I'll give them that much18:32:36
@sorear:matrix.orgsorearI specifically want to avoid a policy which requires no public errata, because that will just push us towards vendors that treat all errata as trade secrets18:33:04
@thefossguy:matrix.orgPratham Patel (you can mention me) me not know that, I’ll look into that tomorrow  18:34:07
@alex:tunstall.xyzAlex
In reply to @hive:the-apothecary.club
catch2-3.5.2-riscv64-linux
I've already encountered this build failure. Here's a fix (probably suboptimal, but it works).
19:18:21
@hive:the-apothecary.clubDr. Wormthanks :fold19:19:44
@hive:the-apothecary.clubDr. Worm* thanks 🙏19:19:49
@alex:tunstall.xyzAlex(The fix is based on skeuchel's PR. You could probably use that PR directly if you use a custom Nixpkgs repository; I don't.)19:20:37
@hive:the-apothecary.clubDr. Wormi don't either19:20:50
@darinmorrison:matrix.orgsilvanshade joined the room.19:42:09
5 Apr 2024
@liberodark:matrix.orgliberodark joined the room.07:46:35
@liberodark:matrix.orgliberodarkHi11:27:42
@liberodark:matrix.orgliberodarkIf you need to work on RISC-V servers, don't hesitate to ask me, I will provide some for free.11:28:51
@liberodark:matrix.orgliberodarkbeing also a small user of nixos it is important to me that everyone can work in good conditions. To improve this architecture.11:30:25

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