T
Three Dots
threedots.ovh · Personal blog · on HN since 2020
Three Dots is a personal technical blog on low-level systems topics like Rosetta on Linux, Drawbridge, AMD ROCm, and CPU memory models.
What HN saysHN links it for the Drawbridge slides behind SQL Server on Linux, a post on CPUs with sequential consistency, and a critical ROCm piece.
24HN people shared it
14linked it in comments
26stories submitted
619story points
7 months agolast shared
2020people per year2026
Most-shared posts
- 1Quick look at user-mode file systems on macOS Ventura – random blog5 people · 4 points · first shared 2022 · discussion on HN
- 2Drawbridge: Documenting a bit something that is undocumented [pdf]5 people · 2 points · first shared 2021 · discussion on HN
- 3AMD ROCm: A Wasted Opportunity3 people · 4 points · first shared 2022 · discussion on HN
- 4Quick Look at Rosetta on Linux2 people · 172 points · first shared 2022 · 41 comments on HN
- 5Huawei ExaGear: x86_64 apps on Arm 64-bit Linux systems2 people · 143 points · first shared 2021 · 58 comments on HN
- 6Drawbridge: What SQL Server on Linux is built on2 people · 63 points · first shared 2021 · 15 comments on HN
- 7Beyond GPU unified memory: fully unified address spaces2 people · 4 points · first shared 2022 · discussion on HN
- 8What Is AMD ROCm?1 people · 99 points · first shared 2021 · 56 comments on HN
- 9Open-source drivers according to Habana1 people · 80 points · first shared 2022 · 23 comments on HN
- 10OpenCL on Metal – what if clvk works?1 people · 25 points · first shared 2022 · 9 comments on HN
- 11Nvidia GSP Firmware1 people · 3 points · first shared 2021 · discussion on HN
- 12Boot drive encryption security on Windows1 people · 3 points · first shared 2022 · discussion on HN
- 13The case for mapping PCIe BARs as device memory on arm641 people · 3 points · first shared 2022 · discussion on HN
- 14CPU Pinning on macOS1 people · 2 points · first shared 2022 · discussion on HN
- 15Virtualising GPUs: The Different Approaches1 people · 2 points · first shared 2022 · discussion on HN
What HN people wrote when they linked it
tech234a · 2023-01-18
Worth noting that already did this to support SQL Server on Linux [1].
[1]: https://threedots.ovh/slides/Drawbridge.pdf
qalmakka · 2026-03-25
AFAIK it's more like a reimplementation of NT APIs in userspace - aka basically Wine with extra steps, or Linux UM. There was a slide deck going around about Project Drawbridge, here: https://threedots.ovh/slides/Drawbridge.pdf
astrange · 2025-08-20
Fujitsu and Nvidia also implement (at least) TSO.
https://threedots.ovh/blog/2021/02/cpus-with-sequential-consistency/
anybody8824 · 2025-02-09
You could try to use the Win32 debug API in the same way like Linux UML by using ptrace. But it would probably still be much slower because of missing things like PTRACE_SYSCALL.
More performant would be a noMMU variant of UML for Windows, supporting only PIE executables, similar to nabla-linux [1]. This is also quite similar to how mssql for Linux works NT kernel+Win32 in a single usermode process (single address space) [2]. Interestingly, mssql also uses memory protection keys to recover a bit of fault tolerance but last time I checked Win32 does not have an API for MPKs.
[1] https://github.com/nabla-containers/nabla-linux
[2] https://threedots.ovh/slides/Drawbridge.pdf
morbicer · 2024-07-08
Doubt. Wake me up when they can compete with CUDA. ROCm isn't there https://threedots.ovh/blog/2022/05/amd-rocm-a-wasted-opportunity/
lxgr · 2023-12-27
They already have something like this, it's just not a public API and only used for their own FAT and NTFS implementations: https://threedots.ovh/blog/2022/06/quick-look-at-user-mode-file-system…
macshome · 2023-12-26
Apple started replacing their own file system (and networking) kexts with user-mode file systems in macOS 13. Right now its locked up behind some private entitlements though. Hopefully they open it up more in the future.
For a quick overview check out a blog post on threedots. https://threedots.ovh/blog/2022/06/quick-look-at-user-mode-file-system…
sharikous · 2022-06-19
There is that: https://threedots.ovh/blog/2022/06/quick-look-at-user-mode-file-system…
But userspace filesystems are already present in iOS so you can find some reverse engineered info on that (e.g. in Jonathan Levin's books)
saagarjha · 2022-06-14
azinman2 · 2022-06-10
Says so here, which was posted earlier this week. I cannot verify it’s accuracy. I do work for Apple but not at all on related stuff.
https://threedots.ovh/blog/2022/06/quick-look-at-rosetta-on-linux/
Rucadi · 2022-01-28
Have you tried
https://threedots.ovh/blog/2021/01/huawei-exagear-x86_64-apps-on-arm64…
maybe it works faster than qemu for a chrooted environment.
my123 · 2021-01-20
Some more explanations about the choices taken for the first submission: https://threedots.ovh/blog/2021/01/linux-on-apple-silicon-macs-first-r…
trollied · 2021-01-13
Here's the actual slide deck that the short blog posts links to: https://threedots.ovh/slides/Drawbridge.pdf
skissane · 2023-03-04
> Want to use FUSE? Not on your work computer locked to high-sec mode as you cannot install kernel extensions (where is our user space FS Apple?).
It exists already - https://threedots.ovh/blog/2022/06/quick-look-at-user-mode-file-system… - it is just that Apple hasn’t made the API public, and (AFAIK) won’t give you the entitlements necessary to use it. But, both are issues Apple could fix relatively easily - if they wanted to - and here’s to hoping the fix is coming soon
However, there is an alternative that works right now - have your user-space filesystem process act as an NFS or SMB server, and mount that. From what I’ve heard - https://lists.nfs-ganesha.org/archives/list/[email protected]… - macOS even supports mounting NFS filesystems over Unix domain sockets, which has performance and security advantages over IP loopback