| 19 Feb 2024 |
 sorear | they also mis-implemented fence decoding and report illegal instruction extensions for many valid fences | 13:26:05 |
| sorear | the last one also applies to c908 which has nominally standard 1.0 vectors | 13:26:19 |
| sorear | those four are the only userspace-breaking errata I currently know about and none of them have the potential to cause miscompiles. fedora is building some packages on a pioneer box | 13:27:04 |
 Pratham Patel (you can mention me) | huh... AFAIK, David explicitly mentioned not using it as a build box | 13:28:18 |
| sorear | that said the th1520 is slower in practice on compilation workloads than vf2 and the pioneer is only slightly faster some of the time | 13:28:28 |
| sorear | i think they're only using it situationally, one of them mentioned using it for ghc recently | 13:29:08 |
| Pratham Patel (you can mention me) | In reply to @sorear:matrix.org
that said the th1520 is slower in practice on compilation workloads than vf2 and the pioneer is only slightly faster some of the time this is what the Lichee 4A uses, right? | 13:30:27 |
| sorear | i've been calling the situation "new golden age of processor errata" for years, i just don't see a need to single out t-head and I'm paranoidly wondering whether they get held to a different standard because of geopolitics | 13:30:48 |
| sorear | yes (lp4a=th1520) | 13:30:56 |
| Pratham Patel (you can mention me) | probably | 13:31:17 |
 Steven Keuchel | In reply to @sorear:matrix.org
t-head has a userspace erratum where the FP underflow flag is incorrectly not set if a multiply rounds away from zero to produce the smallest normal number, AFAIK the only thing this affects is the glibc regression test suite thanks for that! I am going to read up on it. | 13:44:25 |
| sorear | In reply to @skeuchel:matrix.org
thanks for that! I am going to read up on it. https://github.com/revyos/revyos/issues/17 fwiw | 13:46:22 |
 Alex | In reply to @thefossguy:matrix.org
So far, the only machines I trust for building nixpkgs are the HiFive Unmatched and the VisionFive 2. You should also count the Star64, because it uses the same SoC as the VF2 (unless you have a reason for excluding it too?) | 14:33:01 |
| Pratham Patel (you can mention me) | Ah no reason to exclude it, just forgot about it! :D | 14:33:26 |
| Alex | On the topic of implementation errata, I wonder if anyone's doing any exhaustive testing on the various RISC-V processor designs... | 14:34:10 |
| Pratham Patel (you can mention me) | there are a million (hyperbole) Indian startups doing exactly that! | 14:34:52 |
| Pratham Patel (you can mention me) | the last tenstorrent event almost a year ago in BLR was exactly that :) | 14:35:15 |
| sorear | it's hard to exhaustively test anything of that size, especially when the specs themselves are nondeterministic (memory ordering, counters) or just plain ambiguous | 14:37:22 |
| Alex | In reply to @sorear:matrix.org
it's hard to exhaustively test anything of that size, especially when the specs themselves are nondeterministic (memory ordering, counters) or just plain ambiguous Yes, that's very fair. I'd expect some amount of testing to be possible by exploiting a deep understanding of the processor design, but that's by no means simple. | 14:39:43 |
| sorear | the interesting bugs all happen because somebody miscommunicated or misunderstood the requirements | 14:40:34 |
| Pratham Patel (you can mention me) | one thing I--as a software guy and a negative XP in hardware--understand is, at that point, you're not just verifying the RISC-V ISA but also the microarchitecture :) | 14:40:47 |
| * Pratham Patel (you can mention me) is afk for dinner | 14:40:54 |
| sorear | the ISA is what it is. it can be stupid or contradictory but not wrong, because there's nothing for it to be wrong against | 14:41:37 |
 White Whale | In reply to @nickcao:nichi.co
If you really want some decent remote desktop experience, I would recommend wayvnc (or others), rather than this poorly packaged xrdp. I tried to install wayvnc, it fails with modemmanager build failing to find python. For now I’ve built image w/o VNC, I’ll try to build VNC on board. | 19:06:12 |
| 23 Feb 2024 |
|  KREYREN ⚡️🦀 (TH1520 in Licheepi 4A) changed their profile picture. | 03:28:34 |
| 26 Feb 2024 |
|  JamieMagee joined the room. | 05:04:08 |
| 28 Feb 2024 |
|  Michael joined the room. | 09:53:23 |
| 29 Feb 2024 |
|  marijan joined the room. | 07:08:00 |
| 1 Mar 2024 |
 fgaz | Scaleway now hosts RV servers based on the TH1520 https://labs.scaleway.com/en/em-rv1/ | 13:16:48 |
| fgaz | Maybe this is enough for some temporary nix-community builders? | 13:17:17 |
