Thanks for the video. I am studying the DMA engine and tried to replicate your work as in your video. I stuck at the line of dma_request_channel(mask,NULL,NULL) as it returns error but I have no idea how to fix. Are there anything I can try to print errors out with more details ?

from a generic security point of view a whole Linux systems is as it now days just an endless and hopeless mess security holes waiting to be exploited

Esther Ranch

Very odd to see someone typing code mainly. What is the point.

as I know, S_IRUGO is read-only for all users but I can see that you are able to change the value of the params. Could you explain it to me?

This is incredibly clutch! Thank you for taking your time to post this up!

what are the prerequisites for this course?. I know C, C++ and I am studying Computer Science. But my practical knowledge is not very good. I am trying to improve my skills.

hi getting this on pi 5 still Sean@raspberrypi:~/Programming/LinuxDeviceDriver $ make make -C /lib/modules/6.6.47+rpt-rpi-2712/build M=/home/Sean/Programming/LinuxDeviceDriver modules make[1]: Entering directory '/usr/src/linux-headers-6.6.47+rpt-rpi-2712' ERROR: Kernel configuration is invalid. include/generated/autoconf.h or include/config/auto.conf are missing. Run 'make oldconfig && make prepare' on kernel src to fix it. make[2]: *** [/usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:817: include/config/auto.conf] Error 1 make[1]: *** [/usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:246: __sub-make] Error 2 make[1]: Leaving directory '/usr/src/linux-headers-6.6.47+rpt-rpi-2712' make: *** [makefile:4: all] Error 2

using a pi5, getting make file issues any idea, thx sean Sean@raspberrypi:~/Programming/LinuxDeviceDriver $ make --trace makefile:4: target 'all' does not exist make -C /lib/modules/6.6.47+rpt-rpi-2712/build M=/home/Sean/Programming/LinuxDeviceDriver modules make[1]: Entering directory '/usr/src/linux-headers-6.6.47+rpt-rpi-2712' /usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:246: target '__sub-make' does not exist make --no-print-directory -C /usr/src/linux-headers-6.6.47+rpt-rpi-2712 \ -f /usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile modules /usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:817: target 'include/config/auto.conf' does not exist test -e include/generated/autoconf.h -a -e include/config/auto.conf || ( \ echo >&2; \ echo >&2 " ERROR: Kernel configuration is invalid."; \ echo >&2 " include/generated/autoconf.h or include/config/auto.conf are missing.";\ echo >&2 " Run 'make oldconfig && make prepare' on kernel src to fix it."; \ echo >&2 ; \ /bin/false) /usr/src/linux-headers-6.6.47+rpt-common-rpi/arch/arm64/Makefile:59: update target 'stack_protector_prepare' due to: prepare0 /usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:1819: update target 'prepare' due to: stack_protector_prepare if [ -z "y" ] && [ "gcc-12 (Debian 12.2.0-14) 12.2.0" != "gcc-12 (Debian 12.2.0-14) 12.2.0" ]; then \ echo >&2 "warning: the compiler differs from the one used to build the kernel"; \ echo >&2 " The kernel was built by: gcc-12 (Debian 12.2.0-14) 12.2.0"; \ echo >&2 " You are using: gcc-12 (Debian 12.2.0-14) 12.2.0"; \ fi /usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:1946: update target '/home/Sean/Programming/LinuxDeviceDriver' due to: prepare make -f /usr/src/linux-headers-6.6.47+rpt-common-rpi/scripts/Makefile.build obj=/home/Sean/Programming/LinuxDeviceDriver need-builtin=1 need-modorder=1 /usr/src/linux-headers-6.6.47+rpt-common-rpi/scripts/Makefile.build:41: /home/Sean/Programming/LinuxDeviceDriver/Makefile: No such file or directory make[3]: *** No rule to make target '/home/Sean/Programming/LinuxDeviceDriver/Makefile'. Stop. make[2]: *** [/usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:1946: /home/Sean/Programming/LinuxDeviceDriver] Error 2 make[1]: *** [/usr/src/linux-headers-6.6.47+rpt-common-rpi/Makefile:246: __sub-make] Error 2 make[1]: Leaving directory '/usr/src/linux-headers-6.6.47+rpt-rpi-2712' make: *** [makefile:4: all] Error 2 Sean@raspberrypi:~/Programming/LinuxDeviceDriver $

thank you!

3:05 wait did you just use multiline comment for 1 line comment?

I found changing the name of the ENABLE_PIN macro to EN_PIN (or something other than ENABLE_PIN) solved that error.

It would be nice if you could do this in a Windows environment, using Qt creator, C++, with a simple GUI.

where is the code？

Could you detail why `pgoff = phys_addr >> PAGE_SHIFT`? Is that because each page has an ID which is stored in the first PAGE_SIZE bits of each page (and that the allocated data "begins" only after - this is how I understand it)? Or a similar reason? What if you do `pgoff = phys_addr` instead of `pgoff = phys_addr >> PAGE_SHIFT`?

Thanks for these videos. Can you explain a little about what reference sources you use? For example, what do we do as developers if we do not already know the paramter order for gpio_direction_output() function? What is a good place to quickly look that kind of information up? The header file? manpages?

Just in case anyone else sees this issue: I found I needed to include the -n flag on echo, otherwise the value seen from echo 1 was actually 10

Hi Johannes, Thanks for these videos, they rock! I was wondering about why the buffer_pointer is updated to the to_copy value, rather than delta. If copy_from_user returns a non-zero not_copied result, would we not want the driver_read function to pick a to_copy value corresponding to the delta?

What is the name of the OS you have ported on pi ?

Oh baby im ready, so happy someone is doing this haha

Great video but my_rproc_probe() has an error. After rproc_add. But I guess that is intentional to make sure we are paying attention. 👍 s

does this device has a device tree? Suppose so i guess.

Where did you get that presentation template?

Thank you for touching on what the mode numbers mean! Another person said "just set this to '0666'" and I'm thinking "I know there's such a thing as a demon in computing, but this seems wrong"

Which Linux you booted on your Raspberry Pi?

I love how you showed the real steps and thought-processes that went into this, that was incredibly relatable and helpful. Congratulations!

I really appreciate your videos. Thank you for producing such informative content.

Hi, The BAR's are mapped to some 32-bit address right, Are there any possibilities to use/access those addresses? How?

This is the RU-vid channel that I've been looking for!!

I don't quite understand. Are there 2 types of DMA controllers? One inside PCI device (if device provides it) and another in CPU itself? And can I use any of them to copy data PCI <--> RAM or I have to rely on PCI device (to implement DMA inside) only?

Can you please let me know to get workshop discussion details?

Thanks! have a nice day!

whenever i try to do echo > 1 /dev/my_gpio_driver it doesnt change the value to 1 also there is an error shown in the kernel log as invalid input. can u help me with this?

Only just been watching this - useful pointer on how to get the cp2112 board LED to switch on / off as a way of verifying operation. Just a point of interest: you can use i2cdetect -r -y 'bus-number' to get a listing of addresses via the cp2112 adapter.

How feasible would it be to port an existing Linux driver that you have the source code for to an older windows version? More specifically, Windows 98? The reason I ask is that I am kind of into retro computers and retro gaming and some of the old graphics cards that work in windows 98 are becoming increasingly rare and pricey. So having a driver even for a low end modern graphics card for win 98 would be extremely helpful.

Using this approach, is it possible to pass data from kernel to user space? Replacing the button by a temperature sensor, I get the temperature as an int allocated in kernel space memory: is it possible to pass this int (or a copy of it) to a user space application and covert it into an int allocated in user space memory?

I just found that pwm_request and pwm_free is deprecated and it's not found in Kernel v.6.6. May I ask for a tutorial? I try to find tutorial but nothing comes to mind.

CK h tee cyoyp rhoczieiel niler

thoughts on plan9 arg macros? ARGBEGIN ARGEND etc

A gem in my suggestion list... LOVE IT!

Lopez Kenneth Lewis Amy Robinson Karen

Haha what are the odds that I started learning Ethernet and you dropped a series on this.. excellent. Keep going. A suggestion would be to improve audio quality as I can hear little even on full volume. Or maybe adjustments to mic gain levels would help Thanks

This is going to be a great tutorial series. Thanks!