USB ports in Linux system
When I check "/sys/kernel/debug/usb/devices" in a Linux system, I could see that two devices are on the same port(T: line in below output). Also the port numbers in "D:" line is different.Device1:T:...
View ArticleWhy is their a gap in syscall numbering between 334 and 424 in the x86-64...
In arch/x86/entry/syscalls/syscall_64.tbl syscalls are numbered from 0 to 334 and then there is a gap before the syscall numbers resume at 424. The relevant portion of the source is shown below:...333...
View ArticleDoes libdrm talk to kernel DRM/graphics card via ioctl()?
This can be a silly question as I do not know much about this topic at all... It seems that user applications can talk directly to GPU to render an image, for example using OpenGL, through mesa and...
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What's the relationship between virutal memory and virtual file system
In the figure shown above, the Application passes the FileSystem layer and directly communicate through page cache.After I searched in StackOverflow on how does mmap works, the accepted answer says...
View Articlewhy port information in skb packet parsed at layer 2 does not match with the...
I catch network packet in /net/core/dev.c file at function '__netif_receive_skb_core'. I parse the packet and fetch src_port, destination_port etc. I have taken tcp dump at any interface.But port...
View ArticleWhy isn't my if catching this null pointer dereference?
I'm working with a kernel module, which is causing a null pointer dereference when inserted. I've tracked the error down to this function in swnode.c (not part of the kernel module, but is called by...
View ArticleDisable a gpio-key using the sys interface [closed]
I have a gpio line defined as a gpio-keys in the dts file . I am trying to use the sys interface to enable/disable keys under /sys/devices/platform/gpio-keys/I can see the gpio line when I view...
View ArticleHow to avoid high cpu usage while reading/writing character device?
I need to write a linux kernel driver for a PCIe device with SRAM.For the first attempt, I've written a driver to access SRAM from PCIe with a character device.Everything works as expected, but there...
View ArticlePort information in skb doesn't match with the tcpdump's one
I catch network packet in /net/core/dev.c file at function __netif_receive_skb_core(). I parse the packet and fetch src_port, dest_port, etc. I have taken tcpdump at any interface. But port information...
View ArticleUnable to build AOSP rom on Mac os High Sierra
I'm trying to build an Android 10 rom on Mac OS High Sierra (10.13.6) but even after establishing the build enviroment as it is stated here https://source.android.com/setup/build/initializing I am...
View ArticleLinux Kernel Programming: “Unable to handle kernel NULL pointer dereference...
For a class assignment, we are writing a custom syscall which pulls certain information about the existing process tree. The syscall is working fine for the most part and gets the appropriate...
View ArticleYocto - Device tree incompatibility when changing Kernels in an ARM processor
I'm creating images for iMX chipsets and had downloaded the sources from NXP, and then created a core-image-minimal using Yocto. I then proceeded to sucessfully boot the image in a board.After that, my...
View Articleunable to write /proc/sys/kernel/ns_last_pid file
I want to edit the ns_last_pid file present in /proc/sys/kernel, but i'm getting the error of Read-only file system. How to resolve this?This is what i've written to open the file.int fd =...
View ArticleWhat is causing this kernel oops when parsing firmware?
I'm tweaking a kernel module which registers a bunch of struct software_node linking camera sensors to Intel's ipu3 infrastructure. Once the registration is done, the module triggers reprobing the cio2...
View Articleset_event" causes device to crash (RAMDUMP mode)">Pixel 4XL ftrace: "echo ufs > set_event" causes device to crash (RAMDUMP mode)
I am attempting to analyze read/write activity on a Pixel 4XL (coral) device using ftrace. I can't get beyond "cat available_events | grep ufs > set_event" before the device crashes. I've attempted...
View ArticleMy newly compiled kernel loses Networking in qemu
I compiled a kernel from source :make defconfigmake kvmconfigmake -j 4After this , i use the resulting bzImage for my qemu command:qemu-system-x86_64 -hda debian.img -kernel bzImage -append...
View ArticleExec format error when loading kernel module in LineageOS
I am having a problem with inserting a kernel module in an android system.I managed to cross-compile a kernel module for android using the android-goldfish-4.14-dev kernel and the...
View ArticleCannot get custom kernel to boot - mkinitpcio does not add any modules
1. What I am trying to achieve:Build a custom kernel so I can install and run Anbox-git from AUR on my Arch laptop. Custom kernel is needed for the package to work.2. What I did to achieve it:Download...
View ArticleGetting an error while trying to access struct file private_data
The problem:I have a pointer to struct file called flip, an int called cmd and an unsigned long called arg.The private_data field in struct file pointsthe private_data structure is defined as...
View ArticleProcess Control Blocks in Memory
I want to be able to view the contents of all process control blocks (PCB) in memory. The goal of this is to identify every running process by looking at physical memory alone. I believe that PCBs are...
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