@ABasilPlant@lemmy.world

ABasilPlant

@ABasilPlant@lemmy.world

InfoSec Person | Alt-Account#2

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How System Requests Work and How to Add Your Own SysReq (snee.la)

I needed to add a custom System Request (Sys Req or SysRq) to a linux kernel some time ago. While doing so, I dug deep into how it works and I thought I’d make a quick post about it. Here is a good SuperUser answer about what a SysRq is. You may also know about SysRq via REISUB. This post has three parts: how to raise a SysRq,...

ABasilPlant,

I’m glad you appreciate it! It’s always fun digging into kernel internals and learning new things :D

ABasilPlant, (edited )

No. Fuck this shit. Don’t do this.

It’s already bad when everyone in this community shoves their distro down potential linux-converts’ throats, thereby confusing them even more. Don’t tell (or imply to) freshly converted users that they potentially made a wrong choice.

TF do you think they’re going to do now? Move to fedora? The commenter above already stated that it was a hassle to install Ubuntu and now you’re telling them to change distros already???

Ubuntu is still great… compared to Windows. Sure. It may not hold to your ideals. Compared to other distros, canonical may make some questionable choices. BUT THEY DON’T IMPLEMENT A FUCKING RECALL. So it’s fine (for now).

Ubuntu is fine for newcomers. It has a shit ton of support online and you can easily search questions whose answers are likely to be found within the first few results.

So stop shoving distros down people’s throats, especially fresh users.

I know you said:

Sorry if I sound too hard… take it with a laugh 😁

It doesn’t come across that way. You come off as a gatekeeper.

ABasilPlant,

I knew about the “Thour” meme, but still didn’t get why the directory turned compressed. My guess is that by licking the lemon, the directory folds in on itself, thus becoming compressed.

ABasilPlant,

That checks out - thanks!

ABasilPlant,

For those of you still struggling (like me), here’s an image:

spoilerhttps://lemmy.world/pictrs/image/1811122b-c10d-4900-afa5-98f3aef3a2eb.jpeg

ABasilPlant,

Answered this with a screenshot in this thread:

lemmy.world/comment/10270597

ABasilPlant, (edited )

You haven’t given us much information about the CPU. That is very important when dealing with Machine Check Errors (MCEs).

I’ve done a bit of work with MCEs and AMD CPUs, so I’ll help with understanding what may be going wrong and what you probably can do.

I’ve done a bit of searching from the microcode & the Dell Wyse thin client that you mentioned. From what I can garner, are you using a Dell Wyse 5060 Thin Client with an AMD steppe Eagle GX-424 [1]? This is my assumption for the rest of this comment.

Machine Check Errors (MCEs) are hard to decipher find out without the right documentation. As far as I can tell from AMD’s Data Sheet for the G-Series [2], this CPU belongs to family 16H.

You have two MCEs in your image:

  • CPU Core 0, Bank 4: f600000000070f0f
  • CPU Core 1, Bank 1: b400000001020103

Now, you can attempt to decipher these with a tool I used some time ago, MCE-Ryzen-Decoder [4]; you may note that the name says Ryzen - this tool only decodes MCEs of Ryzen architectures. However, MCE designs may not change much between families, but I wouldn’t bank (pun not intended) on it because it seems that the G-Series are an embedded SOC compared to the Ryzen CPUs which are not. I gave it a shot and the tool spit out that you may have an issue in:


<span style="color:#183691;">$ python3 run.py 04 f600000000070f0f
</span><span style="color:#63a35c;">Bank</span><span style="color:#323232;">: </span><span style="color:#183691;">Read-As-Zero (RAZ)
</span><span style="color:#63a35c;">Error</span><span style="color:#323232;">:  </span><span style="color:#183691;">( 0x7)
</span><span style="color:#323232;">
</span><span style="color:#183691;">$ python3 run.py 01 b400000001020103
</span><span style="color:#63a35c;">Bank</span><span style="color:#323232;">: </span><span style="color:#183691;">Instruction Fetch Unit (IF)
</span><span style="color:#63a35c;">Error</span><span style="color:#323232;">: </span><span style="color:#183691;">IC Full Tag Parity Error (TagParity 0x2)
</span>

Wouldn’t bank (pun intended this time) on it though.

What you can do is to go through the AMD Family 16H’s BIOS and Kernel Developer Guide [3] (Section 2.16.1.5 Error Code). From Section 2.16.1.1 Machine Check Registers, it looks like Bank 01 corresponds to the IC (Instruction Cache) and Bank 04 corresponds to the NB (Northbridge). This means that the CPU found issues in the NB in core 0 and the IC in core 1. You can go even further and check what those exact codes decipher to, but I wouldn’t put in that much effort - there’s not much you can do with that info (maybe the NB, but… too much effort). There are some MSRs that you can read out that correspond to errors of these banks (from Table 86: Registers Commonly Used for Diagnosis), but like I said, there’s not much you can do with this info anyway.

Okay, now that the boring part is over (it was fun for me), what can you do? It looks like the CPU is a quad core CPU. I take it to mean that it’s 4 cores * 2 SMT threads. If you have access to the linux command line parameters [5], say via GRUB for example, I would try to isolate the two faulty cores we see here: core 0 and core 1. Add isolcpus=0,1 to see the kernel boots. There’s a good chance that we see only two CPU cores failing, but others may also be faulty but the errors weren’t spit out. It’s worth a shot, but it may not work.

Alternatively, you can tell the kernel to disable MCE checks entirely and continue executing; this can be done with the mce=off command line parameter [6] . Beware that this means that you’re now willingly running code on a CPU with two cores that have been shown to be faulty (so far). isolcpus will make sure that the kernel doesn’t execute any “user” code on those cores unless asked to (via taskset for example)

Apart from this, like others have pointed out, the red dots on the screen aren’t a great sign. Maybe you can individually replace defective parts, or maybe you have to buy a new machine entirely. What I told you with this comment is to check whether your CPU still works with 2 SMT threads faulty.

Good luck and I hope you fix your server 🤞.

Edited to add: I have seen MCEs appear due to extremely low/high/fluctuating voltages. As others pointed out, your PSU or other components related to power could be busted.

[1] www.dell.com/support/…/system-specifications?guid…

[2] amd.com/…/52259_KB_G-Series_Product_Data_Sheet.pd…

[3] www.amd.com/…/52740_16h_Models_30h-3Fh_BKDG.pdf

[4] github.com/DimitriFourny/MCE-Ryzen-Decoder

[5] www.kernel.org/doc/html/…/kernel-parameters.html

[6] elixir.bootlin.com/linux/…/boot-options.rst

ABasilPlant,

Are you planning to scrap the CPU? I may be interested in it as I find faulty hardware fun to experiment on.

ABasilPlant,

Would you consider sending it to Austria? I’d pay shipping charges (if it’s within reason lol). If you are, you can send me an email at: sneela-hwelemmy92fd [at] port87.com

ABasilPlant,

Thank you, I’ll send you an email within a day.

ABasilPlant,

www.gimp.org/news/2024/…/gimp-2-10-38-released/

This (possibly last) GIMP 2 stable release brings much-requested backports from GTK3, including improved support for tablets on Windows. A number of bug fixes and minor improvements are also included in this release.

If the release says that this is possibly the last GIMP2 stable release, it feels like GIMP3 is actually on its way. I understand your cynicism, but I’d be more optimistic this time around.

ABasilPlant,

In dark mode, the anchor tags are difficult to read. They’re dark blue on a dark background. Perhaps consider something with a much higher contrast?

A picture of a website with a dark purple background and dark blue links.

Apart from that, nice idea - I’m going to deploy the zipbomb today!

ABasilPlant,

Hurd-ng is on its way: www.gnu.org/software/hurd/hurd/ng.html

ABasilPlant,

Edit: nvm I’m an idiot, I just got the joke.

en.wikipedia.org/wiki/Kerning

In typography, kerning is the process of adjusting the spacing between characters in a proportional font, usually to achieve a visually pleasing result. Kerning adjusts the space between individual letterforms while tracking (letter-spacing) adjusts spacing uniformly over a range of characters.

ABasilPlant,

Tiffany spotted

ABasilPlant, (edited )

I used to have the same exact one. For some reason, I can only find similar ones here (Amazon de, in):

www.amazon.de/…/B08HLN4B3B

www.amazon.in/…/B0C14RHW4H

However, searching for “world map large desk mat” yields you similar results.

I’m not sure where I bought that one now hmmm

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