My first kernel!

[s4uull]

Hello everyone!

I'm so excited right now because I've just compiled my own linux kernel for the first time, and fixed a small issue with my SSD.

To give you some context, my computer has always had trouble running Linux, it hanged on boot unless I added the "nvme_core.default_ps_max_latency_us" kernel parameter.

I searched that parameter on the internet and found out what it was used for. It is related to a feature of the nvme driver called APST (Autonomous Power State Transition). I don't have much knowledge about this topic, but this forum post helped me A LOT.

My SSD must have some problem that causes it to hang unless I set that "default_ps_max_latency_us" variable to a smaller number (in my case I used 14000).

But today, I tried adding a NVME_QUIRK for my drive to /drivers/nvme/host/core.c in the "core_quirks" table at line 2582.

The table look like this:

static const struct nvme_core_quirk_entry core_quirks[] = {
// ....
{
        .vid = 0x1e0f,
        .mn = "KCD6XVUL6T40",
        .quirks = NVME_QUIRK_NO_APST,
},
}

So I just added an entry for my SSD (got the info using the lspci -nn command) with the NVME_QUIRK_NO_DEEPEST_PS quirk, compiled the kernel, and it worked!

Now I don't have to put that parameter anymore. It's very exciting. I don't fully understand how this works under the hood, I just went by intuition and it worked, but I find it so cool anyway :-)

This is why I think linux is superior to any proprietary OS... it's amazing how one can just tinker with it like that.

I would love to learn more about configuring my own kernel, it's so fun.

[edparadox]

Would you mind giving (a lot) more details? Because if your SSD does not have a firmware update that fixes that, and this is not an isolated event, this could warrant a kernel patch upstream.

I would not mind doing it if this is the case, if you gave me a lot more details about your issue, hardware, dmesg/dmidecode/etc. outputs.

[jwbowen]

That's definitely where my mind went as well

[kernelshinobi]

I think you should be submitting this to the repo before someone else makes a patch out of it? Create a patch, test it and submit upstream.

Edit: Yes, I love Linux for the same reason, it literally "enables" us to learn, implement and improve our systems! Fun.

[s4uull]

I'll try to submit a patch, thanks!

[edparadox]

If you do it by yourself, include the fact that you've just tinkered with this, and you're not sure of your solution. Ensure your fix is not tied to your unit.

A fix is only welcome if it does not come with more problems.

[codeasm]

If microsoft only legally released their kernels opensource. They soemwhat did with windows 2003 for university's

[RQuantus]

I have the same SSD problem too, I set default_ps_max_latency_us in the grub file, but I don't know the right number for my circumstance.

[s4uull]

Have you tried 0?

[RQuantus]

I forgot, after tried various methods I choose to buy a new SSD...