Oh no, you!

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Joined 2 months ago
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Cake day: November 3rd, 2024

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  • neidu3@sh.itjust.workstoLinux@lemmy.mlGRUB is confusing
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    9 days ago

    You have one per installed kernel. Not sure what (if any) automagic is common for removing old kernels, I guess this varies between distros, but at least on my computers, old kernel remain. At least the previous one, maybe more. It comes in handy in case a kernel upgrade breaks something, which it actually did recently on one of my laptops - makes it easier to boot from old kernel and revert.

    EDIT: I just checked. I have just one on my daily driver. It’s quite new, and I don’t think I’ve had a kernel upgrade on that one, so it makes sense.

    On my work laptop (the one with borked kernel upgrade) I have two.

    So what you most likely have is one or more vmlinuz-version-numbers, and then simply a symlink named just vmlinuz to the version you boot from.


  • neidu3@sh.itjust.workstoLinux@lemmy.mlGRUB is confusing
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    9 days ago

    Short answer to your last paragraph:
    vmlinuz is the kernel. It ends with z instead of x, because it’s z-compressed to save space. (I’ve heard that it’s possible to use an uncompressed kernel for that 1ms faster boot time)
    Initramfs (not intramuscular, which my autocorrect thinks is appropriate) is a small filesystem blob, “initial ram filesystem”, meant to be loaded directly into ram to allow the kernel to talk to your hardware via drivers. It also has a lot of binaries needed to perform other tasks that need to run before the root filesystem is mounted.














  • neidu3@sh.itjust.workstoscience@lemmy.world*Permanently Deleted*
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    2 months ago

    Price: Don’t remember. I fired off a message to the guys in manufacturing, I’ll let you know if they have a price. We go through quite a few of these annually, so we have a bulk discount when buying them.

    How: Magic, I guess. Also, I found a link to the ones we use: https://www.microchip.com/en-us/products/clock-and-timing/components/atomic-clocks/embedded-atomic-oscillators/csac

    When we prepare for deployment, they’re connected to a docking unit which provides a clock pulse derived from a GPS signal for high precision. Then the battery pack is attached, the subsea unit is assembled, and everything is deployed, usually via ROV. It’s important that it’s kept powered the entire time upon retrieval docking, as we can then calculate a linear drift value and correct for this in the recorded data.

    UPDATE: We bought “Maaaaaaany thousands” of them in 2018, and we paid 1850 USD per chip. Come to think of it, I remember hearing claims back then that we’d bought 75% of the worlds supply.


  • neidu3@sh.itjust.workstoscience@lemmy.world*Permanently Deleted*
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    2 months ago

    Some work related trivia I’d like to share with you: My job involves deploying sensors on the seabed to record data. These sensors are battery powered, and rely on highly precise timekeeping to be correct. These devices are synchronized before deployment, and upon retrieval ~2 months later we want none or as little clock drift as possible.

    Tumbleweed sounds

    I’m glad you asked: we achieve this by using CSACs - Chip Scale Atomic Clocks. They are pretty much what the name Implies, and after synchronization it is able to keep the time much better than anything else. Normal clock drift upon retrieval is usually less than a millisecond, and that drift is due to (uninteresting factors not directly related to the CSAC itself)

    CSACs cost a small fortune, but they’re the size of a matchbox and make it all possible. It’s amazing how small atomic clocks can be.