First Kernel Patch - pr_info() doesn't show my message.

sumedh105

Hi All,

I'm using a Lenovo Workstation (desktop machine) with Ubuntu OS running on it.

I tried making changes in the btusb, btintel and uvcvideo driver files. I tried adding pr_info().

I don't see "I made changes in the Linux Kernel driver" message.

Can some one help me with this?

sumedh105

I am blocked on this. It would be great if some one could help me out.

ShuahKhanLF

Did you check if your changed kernel is running? uname -a should tell you. If your kernel is indeed booted and running, do you see uvcvideo in lsmod?

sumedh105

@ShuahKhanLF , thanks for the response. I've confirmed all the above. Below is the output of the same:

sumedh@sumedh-ThinkStation-P348:/swj_linux_work/linux_mainline$ git status
Refresh index: 100% (89748/89748), done.
On branch work
Changes not staged for commit:
(use "git add ..." to update what will be committed)
(use "git restore ..." to discard changes in working directory)
modified: drivers/bluetooth/btintel_pcie.c
modified: drivers/bluetooth/btusb.c
modified: drivers/media/usb/gspca/gspca.c
modified: drivers/media/usb/uvc/uvc_driver.c

Untracked files:
(use "git add ..." to include in what will be committed)
linux_mainline

no changes added to commit (use "git add" and/or "git commit -a")
sumedh@sumedh-ThinkStation-P348:/swj_linux_work/linux_mainline$ uname -r
6.11.0-26-generic
sumedh@sumedh-ThinkStation-P348:/swj_linux_work/linux_mainline$

Below are the some of the questions I'm puzzled about:

1. I am on working on a desktop and I don't have webcam connected. So, does making changes in the uvcvideo driver get reflected in the dmesg?

2. As far configuring module is concerned (Configure CONFIG_USB_VIDEO_CLASS=m), I tried running make menuconfig and I tried to configure this, but, I don't see "USB Video Class (UVC) driver" listed. Ideally, below is what I should see in the make menuconfig right?
   Device Drivers --->
   Multimedia support --->
   USB Video Class (UVC) driver

3. Since I couldn't see the above, I thought I would go ahead and make changes in the btusb and btintel drivers. But adding the pr_info in these driver files doesn't help too. I don't see the prints in the dmesg.

Can you please help me with these questions?

Thanks,
Sumedh W. Jambekar

sumedh105

And here is the output of lsmod which I forgot to mention in my previous reply:

sumedh@sumedh-ThinkStation-P348:/swj_linux_work/linux_mainline$ lsmod | grep uvcvideo
uvcvideo 143360 0
videobuf2_vmalloc 20480 1 uvcvideo
uvc 12288 1 uvcvideo
videobuf2_v4l2 36864 1 uvcvideo
videodev 360448 2 videobuf2_v4l2,uvcvideo
videobuf2_common 86016 4 videobuf2_vmalloc,videobuf2_v4l2,uvcvideo,videobuf2_memops
mc 81920 4 videodev,videobuf2_v4l2,uvcvideo,videobuf2_common

slopixelz

@sumedh105
I am stuck with the same issue.
As for me , sudo dmesg | grep "I changed" doesn't return anything.

Ideally, below is what I should see in the make menuconfig right?
Device Drivers --->
Multimedia support --->
USB Video Class (UVC) driver

As for the 2nd question , UVC is located in -> Device Driver / Multimedia Support / Media Drivers / Media USB Adapters / UVC

slopixelz

@sumedh105

[Update] It worked.

As suggested by @ShuahKhanLF , I wasn't booted into the kernel I had cloned and compiled.

running:

uname -r

returned:

6.11.0-26-generic

...same as yours.
—which is the preinstalled Ubuntu kernel, not the one I built.

I checked the version of the cloned repo using the command:

make kernelversion

which returned:

6.16.0-rc2+

After rebooting into cloned kernel , it worked.
Also, I am on a laptop and i have a webcam so if not having a webcam somehow affects this please share your experience.

sumedh105

@slopixelz , thanks a lot for the comment.

I ran the command make kernelversion and I was indeed not booting the right kernel. As you mentioned, I was booting the preinstalled Ubuntu Kernel.

After booting the cloned Kernel, I see the below message:

I still don't see the uvcvideo driver changes.

Probably this has something to do with the webcam not attached to my desktop machine.

In any case, thanks a lot @slopixelz for helping me out.

sumedh105

sumedh@sumedh-ThinkStation-P348:/swj_linux_work/linux_mainline$ sudo dmesg | grep SWJ
[ 18.575758] SWJ changed the btusb driver in the Linux Kernel
sumedh@sumedh-ThinkStation-P348:/swj_linux_work/linux_mainline$

This is the message I was talking about. Not sure why is it not seen in my previous comment.

slopixelz

@sumedh105 you're welcome and yeah the problem could be something related to webcam not sure