> I pay 0% capital gain tax and use a broker with nearly 0 fees which allows me to rotate for free (almost)
How so?
144 karma · joined February 28, 2023
How so?
However, Xilinx Vivado and Vitis are so obtusely distributed, making it incredibly hard to package them well.
Three random issues I remember:
1. We had a lot of trouble with Vivado projects randomly breaking. The culprit: German localization combined with automatic clock frequency derivation. Depending on which logic blocks where wired up how, you would get i.e. 99.999 MHz instead of 100 MHz. Apparently, Vivado uses a localized printf (or equivalent) to generate TCL scripts. In German localization, the decimal is a comma, which is interpreted as additional argument in the TCL scripts. 2. For simulation, scripts scripts are copied from a template folder to the user folder, and subsequently adjusted. They are copied in archive mode. If the template is read-only to the current user, so is the new copy, thus failing the subsequent adjustment. 3. If you run the installer with --help as argument, it pops up an X window displaying the help. In general, IIRC, we need to run a headless X just to run the installer in CLI/batch mode.
From a Linux distro maintainer perspective, the packaging is horrible. In particular separation of base installation, configuration, and add-ons is non-existent. Large amount of vendored dependencies, only then to depend on the most minute little packages that Ubuntu supposedly ships.
Setting up a reliable, reproducible CI/CD environment based on Vivado is a large headache.
That all goes to say: if anything, AMD/Xilinx should be paying its customers to deal with this. Unless there is a major improvement in the software distribution practices for Linux, I could not justify to my employer paying money for this experience.
On the other hand, if they commercialize on Linux support, there is soooo much that they can improve by a lot, who knows. Hope dies last and all.
- Persistant state? Must declare a volume. - IO with external services? Must declare the ports (and maybe addresses). - Configurable parameters? Must declare some env variables. - Trasitive dependecies? Must declare them, but using a mechanism of your choosing (e.g. via the package manager of your base image distro).
Separation of state (as in persistency) and application (as in binaries, assets) makes updates easy. Backups also.
Having most all IO visible and explicit simplifies operation and integration.
And a single, (too?!?) simple config mechanism increases reusability, by enabling e.g. lightweight tailoring of generic application service containers (such as mariadb).
Together this bunch of forced, yet leaky abstractions is just good enough to foster immense reuse & composability on to a plethora of applications, all while allowing to treat them almost entirely like blackboxes. IMHO that is why OCI containers became this big, compared to other virtualization and (application-) cuntainer technologies.
(Already mentioned) CakeML would be another example, together maybe with its Pancake sibling.
Also: WebAssembly!
Weirdly, when going through the higher assurance levels in aviation, defensive programming becomes more costly, because it complicates the satisfaction of assurance objectives. SQLite (whiches test suite reaches MC/DC coverage which is the most rigorous coverage criterion asked in aviation) has a nice paragraph on the friction between MC/DC and defensive programming:
https://www.sqlite.org/testing.html#tension_between_fuzz_tes...
cargo miri run
Here is a talk about that porting effort:
The term patch-cable seems to be way younger.
This is an excellent introduction to the concept and also to the why complex numbers are used to represent signal samples.
No, not even that (the second thing, passing pointers)! WASM has a different address space (starting from 0), effectively indexing into the WASM module's linear memory. A pointer/reference from the outside env can not be dereferenced from within the WASM bytecode.
The multiple linear memory proposal can circumvent this (allowing you to build something somewhat similar to a simple MMU/address translation engine), but language support for that feature is sparse (AFAIK, Rust does not expose any way to access a different than the default linear memory for example).
There is various hacks around it, but sharing memory block-wise between WASM and outside env is involved already.
- get a suitable cross compiler toolchain
- pick whether you want dynamic or static linking (most likely static when the target system does not come with /nix/store)
- compile all prerequisites for the library such as transitive dependencies
- compile the library with the cross compiler for the selected target arch
All in one command line call, that does not require you to 'apt-get install' any of the tools manually:
nix-build '<nixpkgs>' -A pkgsStatic.libpng --arg crossSystem '{ config = "armv7a-unknown-linux-gnueabihf"; }'Also in some aircraft types these data buses are unfortunately not so very hard to access (i.e. accessible from the cabin, with undetected access being even plausible in some cases). So some resilience might not hurt in these cases.
It's important that failure of critical systems is far less threatening than systems providing plausible, yet incorrect data. Redundancy and monitoring catches most of the former but not the latter.
More interesting IMHO would be what can be done to accelerate the adoption of new technologies (especially w/r/t cryptography) in avionics. This is more than anything a cultural problem; How to convince regulative bodies, how to satisfy processes, how to re-balance the proven-in-use argument (where stuff gets more favorable safety assessments when it has been used long enough) vs crypto-agility (where the same thing from today just tomorrow becomes insecure without changing itself, because of some external discovery).
The technology is there, but the aviation community is not yet. Another nice read in this domain is "Economy Class Crypto: Exploring Weak Cipher: Usage in Avionic Communications via ACARS"[1, 2]. I only say mono-alphabetic substitution cipher.
An interesting connection of Blockchain-tech, safety and security can be found in "Verifiable Computing in Avionics for Assuring Computer-Integrity without Replication" [3]. Here the authors leverages zero-knowledge proofs to prove to a downstream actuator that its commands are indeed correct results yielded by the application of the appropriate control law on the provided sensor inputs. However, this work is probably at least a decade away from being applicable in actual certified aircraft.
[1] https://link.springer.com/chapter/10.1007/978-3-319-70972-7_... [2] https://www.cs.ox.ac.uk/files/9693/fc-paper.pdf [3] https://publ.sec.uni-stuttgart.de/reinhartluettighuberliedtk...