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kijiki

785 karma · joined May 13, 2008

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kijiki··on WatchYourLAN: Lightweight Network IP Scanner
WoL relies on a special magic Ethernet frame being sent to the MAC of the sleeping computer. A normal ARP or TCP SYN from an incoming HTTP request won't do it. The wikipedia article has the exact frame format: https://en.wikipedia.org/wiki/Wake-on-LAN

I've seen setups where the router is configured to send the magic WoL packet when it sees an ARP for the IP of a computer it knows is sleeping, but you'd almost certainly know if you had an exotic configuration like that on your network.

kijiki··on How simultaneous multithreading works under the hood
> on the Xbox Series X we found the same test marginally faster when we scheduled work for SMT too.

This makes sense, the Series X has GDDR RAM, and so has substantially worse latency than DDR/LPDDR. SMT can help cover that latency, and the higher GDDR bandwidth mitigates the higher memory bandwidth needed to feed both threads.

kijiki··on Making a Linux-managed network switch
Their Sparx-5 line is supported by stock upstream Linux switchdev.
kijiki··on Testing AMD's Bergamo: Zen 4c
It decodes to uOPs optimized for the exact microarchitecture of that particular CPU. High performance ARM64 designs do the same.

But in the specific case of tracking variable length instruction boundaries, that happens in the L1i cache. uOP caches make decode bandwidth less critical, but it is still important enough to optimize.

kijiki··on Testing AMD's Bergamo: Zen 4c
It isn't quite that bad. The decoders write stop bits back into the L1D, to demarc where the instructions align. Since those bits aren't indexed in the cache and don't affect associativity, they don't really cost much. A handful of 6T SRAMs per cache line.
kijiki··on Testing AMD's Bergamo: Zen 4c
A dual-issue in-order RISC-V isn't enough smaller than a P54c to make a significant difference. The overwhelming majority of Larabee's area went to SIMD units and caches.
kijiki··on Testing AMD's Bergamo: Zen 4c
There is an absolutely huge difference between a 32c/256t part and a 128c/256t part. And Tera's MTA predated the T1 by quite a bit with a similar (and evidently doomed) architecture...
kijiki··on Swiss' Entire Boeing 777 Fleet Now Has Shark Skin Technology
> Given how huge the A380 is, it is more likely to fly less than completely full

That is quite nice as a passenger, but also a big part of why they're no longer made, and why most airlines are phasing them out...

kijiki··on Sysadmin friendly high speed Ethernet switching
> I have been eyeballing "SparX-5" based switches

Have you found any for sale other than the Microchip dev board?

I stumbled across this recently: https://www.servethehome.com/insane-48-port-2-5gbe-2x-25gbe-... but I haven't been able to find where you can buy one these days.

Sadly my PCB design skills are not quite up to dense BGA escape + 25gig lanes...

kijiki··on Homemade 6 GHz pulse compression radar
>Anyone know how .mil aircraft would interpret being tracked by a 6 GHz radar build by a civilian(yes I am aware that his estimated max distance is 1200m, assume he increased that by a factor of 10 with larger antennas or something)?

No specific knowledge, of course, but I'd imagine it wouldn't trigger a serious threat warning. Military TWRs are highly tuned systems dedicated to the threat environment they're expected to operate in.

kijiki··on Baltimore's Key Bridge struck by cargo ship, collapses
The western span had substantial seismic remediation applied in 2000-2001.
kijiki··on Proposed Windows NT sync driver brings big Wine/Proton performance improvements
How are you finding MSFS to be on Proton?

I found it mostly worked, and then broke controller input about 3-4 months ago, and then partially fixed it last month.

What controller or stick/throttle are you using?

kijiki··on The SR-71 Blackbird Astro-Nav System worked by tracking the stars
> there was a lot of pushback inside the us military on investing in increasing the accuracy of naval ICBMs.

The book "Inventing Accuracy" covers this in detail. Fascinating historical perspective.

https://mitpress.mit.edu/9780262631471/inventing-accuracy/

kijiki··on The History of Windows 2.0
Falcon 3.0 had an optional extra realistic flight dynamics model that required a x87 FPU. Probably drove some sales of the 486DX.
kijiki··on ParkyTowers: Thin Clients Laid Bare
I've been using this $32 15m one for a few weeks: https://www.amazon.com/dp/B098QC6XWS

It claims 8k60, but I've only used 4k60 though.

kijiki··on The subtle magic of tsnet
How do you prevent other processes (or other apps on mobile) from connecting to the service?

A malicious game on my phone can't ssh to my server if I do normal authentication, but with this IP/WG authentication it can...

kijiki··on The 90s Developer Starter Pack
Bug, you want: mov al, 13h
kijiki··on Why Nvidia Keeps Winning
The actual quote from your link is: "Expect a massively programmable, massively parallel and pipelined graphics monster", not a "compute monster".

While I agree that Nvidia positioned themselves well, they were not looking as far forward as you suggest. As I recall it, they seemed surprised by BrookGPU, though they moved quickly to embrace the model.

And there were earlier proto examples of GPU compute that that were completely overlooked: https://web.archive.org/web/20010607021839/http://freespace.... (scroll down to "Optimising with 3D Rendering Hardware")

kijiki··on VT330/VT340 Sixel Graphics
Huh? Does: waypipe ssh remotehost guicmd

not work for you?

kijiki··on First Rust code in the Windows 11 kernel
> Not surprising. Linux is one of the few monolithic kernels.

This is an amusing claim, given that Microsoft's first use of Rust in the NT kernel is in win32k.sys, which is the in-kernel code that used to live in userspace back when NT was actually a microkernel. So pre-NT4, which was released in 1996.

kijiki··on Bcachefs – A New COW Filesystem
Oracle could do what they did with DTrace in 2017, and release it under the GPL in addition to the CDDL. Then the OpenZFS folks would have to track down every contributor to OpenZFS, and get their permission to re-license their contribution. Contributions from folks who refused or couldn't be found would have to be re-implemented or dropped.

It is a pain in the ass, but it has been done before.

kijiki··on Bcachefs – A New COW Filesystem
> If they do not defend their copyright, then it is not strong and can be broken in certain scenarios.

This is not true. Copyrights (like patents) do not have to be actively defended to remain enforceable.

This is partially true of trademarks, however.

kijiki··on Is sequential IO dead in the era of the NVMe drive?
Google, Facebook, Microsoft, Amazon and so forth buy most of the spinning rust, and have for years. Each of them have their own extremely proprietary storage layer that knows how to manage Shingled Magnetic Recording.

So when SMR got released into the open market, it was exclusively drive managed, and mainly on the low-end, as a cost reduction strategy. With all the performance downsides you'd expect.

It is a real shame that host managed SMR isn't available outside the mega-scale corps. It would be nice to have access to an intelligent storage stack mixing flash and SMR drives without having to go work for one of the big N companies.

kijiki··on Build your own private WireGuard VPN with PiVPN
May or may not work for your usecase, but I have some scripts to prepare read-only raspbian images here: https://github.com/nolanl/ropi

There are commands to enable/disable read-write mode, so you can still make changes and do upgrades.

I've had 0 problems with SDcard death after I started using it.

kijiki··on State-controlled media gain Twitter followers after quiet platform policy change
Maybe I'm just getting old, but calling 5 weeks (well, it'll be 5 weeks tomorrow) "long since" seems odd.
kijiki··on AT&T Wireless traffic shaping apparently making some websites unusable
Couldn't ISPs just sniff the SNI hostname to differentiate fast.com vs actual Netflix video streaming?
kijiki··on Zero-1-to-3: Zero-shot One Image to 3D Object
85ms, holy crap, who is your ISP?

On Sonic fiber internet in San Francisco, I get 1.5ms to the POP. It is only 4.5ms to my VM in Hurricane Electrics Fremont DC.

kijiki··on The model for coins in Super Mario Odyssey is simpler than in Super Mario Galaxy
> The Wii, when it was launched, was similar to a 10-year-old PowerBook G3, in a white box.

True for the CPU, but quite unfair to the Wii's ArtX GPU, which was substantially faster and more featureful than the ATI r128 in the PB G3.

kijiki··on The model for coins in Super Mario Odyssey is simpler than in Super Mario Galaxy
Matrox G400 (also 1999) had dot3 bump mapping as well. IIRC, they advertised it as a first in the PC 3d accelerator space, so I'd guess they shipped earlier in '99.

The G400 was generally lackluster at 3d performance, so the feature didn't really get used by games.

kijiki··on Startup Decoupling and Reckoning
A startup I worked for during the .com bubble gave up and returned the remaining cash to investors, something on the order of 10 cents on the dollar. One of the VCs joked? that it was the best return of the year for them.
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