Getting pixel value to be around 65000 even though "MEDIA_BUS_FMT_SBGGR8_1X8"...
I have interfaced thermal camera sensor with TI's soc which runs linux kernel. I am able to get video frame data. When dump it into file it shows that pixel value goes upto 65000. But I have selected...
View ArticleFull form of ttwu in the scheduling code of the linux kernel
I know this is kind of silly, but I tried to find out online, but couldnt.What is the full-form of ttwu in the scheduler code of the linux kernel. It can be seen as a number of function prefixes,...
View ArticleFor a single process, are physical addresses uniquely mapped to a virtual...
I'm new to the linux kernel and it's specific functionalities. I've been trying to understand the mapping between Physical and Virtual Addresses (PA/VA) for certain peripheral addresses on my Pi3 -...
View ArticleUbuntu 20.04 faliled to boot using initrd generated by dracut with lvm and...
I'm trying to enable full disk encryption on Ubuntu 20.04 with tpm2. Here is my stepsInstall Ubuntu 20.04 with LVM and encryption enabled.Install clevis and generate new initrd $ apt install...
View ArticleLinux dynamic kernel loading with overloading device tree
I want to make my own protocol driver for my custom made spi board. The platform on which I want to attach it is a raspberry Pi4 with arm32. I want to load it dynamically with an overlay device tree.I...
View ArticleRun GDB with Linux
I'm trying to run gdb with linux kernel. I built linux with CONFIG_GDB_SCRIPTS=y, and tried to run python script "vmlinux-gdb.py" in gdb, which is in "../linux/scripts/gdb". But as result I got...
View ArticleWhich processor would execute hardware interrupt in a muticore system
In general hardware interrupts need to be processed immediately, at least so as to acknowledge it and do some first level of processing. As I understand this is not scheduled activity. Please correct...
View ArticleUnable to type anything on the kdb prompt in virtualbox
I have enabled KGDB/KDB in the kernel configuration and installed the kernel on virtualboxAdded 'kgdbwait kgdboc=ttyS0,115200' into kernel command line.When i boot into the kernel, it would give me kdb...
View ArticleCreating a TUN device on Ubuntu VM doesn't seem to work
I wrote a script that would create and print the name of a new TUN interface on an ubuntu VM using python.import fcntlimport structimport osimport subprocess#from scapy.all import *TUNSETIFF =...
View Articlealign macro kernel
I am unable to understand what this macro does. These are defined in linux-kernel but my doubt is independent of that. I am unable to understand what does (((x)+(mask))&~(mask)) line does.#define...
View ArticleWhat happens if header doesn't match with kernel when compiling module?...
We're recompiling a device driver for 64-bit Centos 8.1 (4.18.0-147.el8.x86_64 #1 SMP Wed Dec 4 21:51:45 UTC 2019 x86_64) but the compilation failed because the signature of...
View ArticleWhy getpid() is not implemented in x86_64's vdso?
After glibc 2.25, glibc's getpid() wrapper no longer cache its result.However, on x86_64 vdso didn't provide getpid() function.Which means everytime getpid() is called, a syscall is triggered.I am...
View ArticleBundle packages with kernel
How GNU/LINUX packages are selected, and how the kernel and packages are bundled together?apt list --installed lists all the gnu packages but how to select anyone and bundle it with the kernel.
View ArticleWhich registers are protected from user space in linux?
How can I find out which registers are protected by the Linux kernel to keep user assembly from writing to them?
View ArticleWhy are many system calls (getpid) captured only once using strace?
I invoked getpid() in a program for many times (to test the efficiency of system calls), however when I use strace to get the trace, only one getpid() call is captured.The code is simple:#include...
View ArticleMinecraft Forge on Raspberry pi
I trie to install a 1.12.2 minecraft forge server on a Raspberry 4. But I get this error:No X11 DISPLAY variable was set, but this program performed an operation which requires it. at...
View ArticleLinux compilation | Invalid entrypoint
I am compiling a downstream linux using mipsel toolchain.Everything works fine except at the very last point which states invalid entry point:sh: 0: Can't open /arch/mips/boot/tools/entryrm -f...
View ArticleHow can the Linux kernel use specific processor in multiprocessor? [closed]
I'm new to low level knowledge such as assembly language or linux kernel. While studying how the CPU executes instructions, a questions arises.In the case of a multiprocessor, how can the linux kernel...
View ArticleLinux kernel build compile errors stringop-overflow and sizeof-pointer-memaccess
I have tried building the Linux kernel and I have got some compile errors. Does anyone know what I am doing wrong and how I can fix it? (Or, what additional information do you need?)Build system is...
View ArticleCan a Linux process/thread terminate without pass through do_exit()?
To verify the behavior of a third party binary distributed software I'd like to use, I'm implementing a kernel module whose objective is to keep track of each child this software produces and...
View Article