- kernelnewbies@kernelnewbies.org - Kernelnewbies Mailing Lists

Re: Vmalloc.h implicit functions
by Valdis Klētnieks Sept. 15, 2021

Sept. 15, 2021

On Wed, 08 Sep 2021 07:46:13 +0200, Omar Mustafa said: > Okay my kernel is 5.13.9-generic and I have tried what you mentioned but failed > the only remaining solution I can think of is trying to install the Windows > driver through NDISWrapper and it’s the RTL8822BE Bluetooth not the WiFi First, Linux kernel email conventions are that you do a "reply all", so that others can comment even if I'm busy or don't know the answer. I've re-added kernelnewbies to the cc: list. Second, you still haven't said what driver you were trying to fix. The rest of us can't help with an out-of-tree driver unless we know where it's from. Also, can you give us what lspci or lsusb says your widget is?

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Understanding merge window and next-tree
by Lafan Mining Sept. 11, 2021

Sept. 11, 2021

I'm trying to understand how Linux Kernel development works and reading the relevant documentation at https://www.kernel.org/doc/html/latest/process/2.Process.html So there is the so called next-tree accumulating all the patches from all the subsystems ready for merge and the mainline tree. The thing is the merge-window is opened for 2 weeks (as mentioned in the linked documentation) and as far as I understood all the changes will be merged into the mainline. But looking through the next-tree I found some implementation in Rust https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/log/rust which is much older than 2 months. How is that happened that after a few merge windows (4 if I counted correctly) it's still not merged? Thank you!

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ASoC/ALSA Out of Memory Issue
by Alex Roberts Sept. 10, 2021

Sept. 10, 2021

Hello, I am developing a dummy codec to interface with an 8-channel, 24-bit ADC. I've got it working on an NXP imx8m through the fsl_sai driver on kernel 5.4.85. I can capture all 8 channels at varying sample rates using arecord, and I've verified correct data capture via opening the resulting .wav file in Audacity. The problem I am having is that occasionally, upon starting arecord - after a fresh power cycle - I get an out of memory error. Other times I get an out of memory after a non-deterministic period of capture. Starting capture again also reports out of memory, but if I wait several minutes and start capture it will start recording again. A power cycle usually helps, but as stated earlier, not 100% of the time. I'm trying to track down where the oom error is coming from, but haven't had much luck. My colleague tried running arecord with valgrind to check for memory leaks and nothing of note was observed. My suspicion is there's something going on with allocated memory for DMA, like fragmentation starts to happen and it can't get a contiguous region for operation. Reserving a larger pool - either via device tree or kernel cmdline arguments in the bootoader - did not seem to help. Another thought is that it's a boundary/alignment issue due to the 24-bit data, and the error is the result of trying to allocate a chunk of memory for DMA that doesn't align. I'm very new to ALSA dev with some exposure to kernel dev in general, so please correct me if I'm wrong or completely mis-understanding something. Any suggestions on where I should / how I can debug this memory error? Thanks, Alex. PS: Previously sent this to just alsa-devel mailing list on 7/21, but never saw it show up in the archives. Here is more info since then: The goal is 8-channel, 96k sampling rate. I've reduced sampling rate and still have the issue. Reducing down to 4-channels helps, but haven't tested long term enough to evaluate by how much. Narrowed it down to device_prep_dma_cyclic(..) returning NULL within dmaengine_prep_dma_cyclic(..)..... still tracing through source to learn exactly what is going on.

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Kernel upstream compile error at drivers/staging/media
by Lafan Mining Sept. 10, 2021

Sept. 10, 2021

Hello! I'm learning the Linux Kernel and currently faced troubles with building the upstream. I git clone'd source code of master and tried to make deb-pkg. I faced compile error: drivers/staging/media/atomisp/pci/hive_isp_css_common/host/input_system.c: In function ‘input_system_configure_channel_sensor’: drivers/staging/media/atomisp/pci/hive_isp_css_common/host/input_system.c:1649:1: error: control reaches end of non-void function [-Werror=return-type] 1649 | } What this error could be about and how to fix it? Maybe some wrong compilation flag is the cause? Thank you!

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When to use torvalds/linux.git and next/linux-next.git
by Lafan Mining Sept. 10, 2021

Sept. 10, 2021

I recently came across a situation when [https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/](https:… contained a code that was failed to compile, but [https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/](https… contained a valid code with the applied patches. So I generally confused about what repo should be used to test patches before patch submit? Thank you!

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Vmalloc.h implicit functions
by Omar Mustafa Sept. 7, 2021

Sept. 7, 2021

Hi all, I’m trying to install some modules but yet I fail with those errors: error: too many arguments to function ‘__vmalloc’ 157 | __vmalloc(load_driver->sys_files[i].size, ./include/linux/vmalloc.h:132:14: note: declared here 132 | extern void *__vmalloc(unsigned long size, gfp_t gfp_mask); Hence, make fails every time. I was hoping whether there is any solution to this problems since Bluetooth driver build for example fails and I need it working for some IoT projects I am currently working on. And if someone could mention Linus Torvalds I’d very much appreciate it.

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Kernel bug tracker
by Adverg Ebashinskii Sept. 6, 2021

Sept. 6, 2021

Hello. I’m a kernel newbie and try to get involved into the Kernel development. So I’d like to start with small bug fixes related to any subsystem (fs is preferred since I familiar with it the most) or something like that. Is there some kernel bug tracker where anybody could pick a bug to fix and then send patches? -- Regards, Adverg Ebashinskii

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Patch Review Process?
by Andrew D Adamson Sept. 5, 2021

Sept. 5, 2021

I've seen lots of blogs, keynotes, and docs on the process for submitting patches, but I can't really find a write up on how the review process works. Is there a best practice for finding patches pending review other than watching the all mailing lists? I saw the patchwork.kernel.org server can track patches with 'action pending' but I'm not sure if that means it needs review or a maintainer to accept it. -- Andrew D Adamson <andrewdadamson(a)gmail.com>

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Re[6]: Kernel bug tracker
by Adverg Ebashinskii Sept. 5, 2021

Sept. 5, 2021

Hi Valdis, > You might want to read this Thanks for the info it was very interesting to read. My primary intention of getting into the Linux Kernel Development is that I myself used to be a C/Linux developer for years on the user side and pretty well-versed in the Linux user-space API. But the thing is that I have almost zero knowledge of what actually going on under the hood and how to debug and fix complicated problems related to the Kernel itself. So this is the reason of my interest precisely to core subsystems. -- Regards, Adverg Ebashinskii

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How to debug the very first part of kernel
by 候磊 Sept. 4, 2021

Sept. 4, 2021

I've read some kernel code recently, and I want to see how it actually works. I found a lot of articles about how to debug kernel with qemu, but all i found are about setting a breakpoint at start_kernel, so i wonder if there's way i can debug before start_kernel, those setup code and decompression code in arch/x86/boot folder. More specifically, I want to debug start at 0x200 offset of kernal image if I'm not misunderstanding boot protocol document. I would be appreciated for any reply and i'm sorry if i have weird english expression.

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