Notices by Per Vognsen (pervognsen@mastodon.social)

@whitequark ... for all who celebrate (me)

Firefox just lost all my pinned tabs because of this brilliant design: https://superuser.com/questions/1825979/firefox-loses-pinned-tabs

@whitequark IFF is still the goat format.

@whitequark @rygorous @chrisvest This also reminded me that Xilinx had their own truly awful DLX-inspired ISA for MicroBlaze but it looks like the newer MicroBlaze cores are RISC-V as well: https://en.wikipedia.org/wiki/MicroBlaze

@whitequark @rygorous @chrisvest Xtensa too. Since the core ISA never seemed to be the main selling point (although Xtensa had some interesting ideas like a newer take on register windows and 24-bit RISC instructions) and if anything was a detriment insofar as they're relatively niche when it comes to the software ecosystem, I'm not surprised RISC-V is taking over there.

@whitequark I think it disappeared when we all deleted our Twitter accounts but there I remember a thread with me and @rygorous with "Imagine having 'Did bring-up for OpenVMS on Kittson [the last gen of Itanium] on your resume" after we saw a particularly cursed thing.

@nikitonsky The sharp tip of the triangle looks like it's ever so slightly upward curving due to an artifact of the drop shadow.

@whitequark Do they mock people who use optical microscopes?

@whitequark You can use shared libraries with emscripten? Huh. And it looks like it maps directly to Wasm modules. That's convenient.

@whitequark *callcc has entered the chat*

Revisiting some of my old Rattle HDL design ideas for Python (with a Rust-based core) with an eye towards seeing how much you can make things work with a statically type checkable facade while doing metaprogramming behind the static type checker's back. This statically type checks with pyright: https://gist.github.com/pervognsen/fc6a19d6c021f49826beea0c8840cc53

@whitequark @azonenberg @gsuberland I mean... https://gitlab.com/VC6Ultimate/VC6Ultimate/-/raw/master/VisualUltimate/Help/bEnableImagePopup.gif

@whitequark @azonenberg @gsuberland The culture of extensive reverse engineering and binary patching to extend proprietary dev tools on Windows has always made me smile. This is one of the crazier examples: https://gitlab.com/VC6Ultimate/VC6Ultimate

HDL fiddling randomly got me thinking about old FPGA carry logic hacks: https://gist.github.com/pervognsen/c62cdb4c73b3321d9d9ab48d0898ffc2

@brouhaha @rygorous Fabian can clarify further but I thought it did happen without overclocking, just with extreme rarity? The overclocking is used to make it reproducible in a lab setting.

To extend the analogy I guess you can also add to this revocable capabilities if you selectively indirect through a mutable oracle store with random GUIDs as keys and content hashes as values. You should end up with some kind of forward-secure version of the downward-closure property where you can only access content which is reachable from known content hashes without going through revoked links.

So if you don't know anything, you're completely stuck. You need at least one root hash. And if that's valid you get at the content and from there you can do the usual thing of following hash-links to get other content. But you have a kind of transitivity or downward-closure principle that seems almost the same as with object-capability security. Like, I obviously understood this is how Git and other CAS systems work, I just hadn't formulated it to myself as an information-security thing.

Something I hadn't really considered before (I'm sure old news to security folks) is that there's an information-theoretic security principle with content-addressable storage that is reminiscent of object-capability security. You can't "guess" content hashes in an ideal oracle CAS (i.e. no timing leaks/side channels). So you can only access content by querying the CAS if you either already have the content or if you received a content hash from someone or somewhere else.

This talk by Greg Law from undo.io covers the design space of time-travel debugger implementation so you'll see learn how rr, undo and WinDbg/TTD work under the hood: https://www.youtube.com/watch?v=NiGzdv84iDE

@j2kun For example, if you mark the start and end of a range with a 1 bit then the running parity is a mask vector to select the bits in those ranges. You can even use this for computing rasterization coverage masks for potentially overlapping polygons where overlaps are resolved with the "mod 2" rule.