bizarre network problem on kernel 6.6.4

[Kalle Valo]

Fourhundred Thecat <400thecat at ik.me> writes:

> On 05/12/2023 13.11, Kalle Valo wrote:
>> Fourhundred Thecat <400thecat at ik.me> writes:
>> 
>>> I have the most bizarre network problem on my laptop that I have ever
>>> seen, and I don't even know where to start:
>>>
>>> This is lenovo T14s Gen 4, using qualcomm driver ath11k_pci
>>>
>>> Previously I was using kernel 6.6.1 and wireless network was working fine.
>>>
>>> Now I compiled kernel 6.6.4 with identical config, and when I boot it,
>>> wireless network does not work:
>> 
>> Did you verify that booting back to 6.6.1 fixes the problem? That would
>> rule out that this isn't due to some external reasons (user space or
>> network)
>> 
>> If you can verify that 6.6.1 always works and 6.6.4 always fails I would
>> just try to git bisect the issue. It shouldn't take too long.
>
> yes. I verified multiple times that 6.6.1 works, and 6.6.4 has this problem.
>
> I am not really familiar with git bisect, and I am also not a kernel
> developer.

git bisect is a very useful tool, I recommend learning it as it makes so
much easier to find the culprit for regressions. You don't have to be a
kernel developer, it's enough that you know how to compile and install a
kernel.

Here's one doc I found with google, hopefully it helps:

https://wiki.gentoo.org/wiki/Kernel_git-bisect

Here's one from kernel documentation:

https://docs.kernel.org/admin-guide/bug-bisect.html

> But I tried checking out linux kernel git repository, switched to tag
> 6.6. and looked inside drivers/net/wireless/ath/ath11k trying to spot
> any change. But git log shows last change on 2023-08-30, whereas kernel
> 6.6.4 was released few days ago

I assume you were looking at Torvalds' tree only. The release 6.6.4
means that you are using a stable release which are in linux-stable
tree, the gentoo doc above should help more.

-- 
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https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches