Workqueue handling if the same interrupt occurs before workqueue finishes
In Linux,I have an ISR and I want to schedule a workqueue to push my work to bottom half. Now I have a situation where the workqueue has not finished its task and the same interrupt occurs again. Now...
View ArticleWhat are these flags for workqueue means?
While studying workqueue, I came across WorkQueue flags & constants defined in kernel. I have following doubts which i could not understand.What exactly draining & rescuer mean here?WQ_DRAINING...
View ArticleWhat is the difference between tasklet and workqueue
I am a Linux device driver newbie, and want to know the exact differences between tasklet and workqueue. I have the following doubts:Which kernel stack do interrupts, tasklet and workqueue use when...
View ArticleWorkqueue implementation in Linux Kernel
Can any one help me to understand difference between below mentioned APIs in Linux kernel:struct workqueue_struct *create_workqueue(const char *name); struct workqueue_struct...
View ArticleKernel Oops when calling aio_complete by workqueue
Short Edition of the question:Process submit IO through io_submit(file open with O_DIRECT). When kiocb->ki_complete(aio_complete_rw) is called in fs address_space_operations .direct_IO, everything...
View ArticleHow can I compile the Linux Kernel getting the output of the preprocessor too?
I know that with gcc -E you can get the output of the preprocessor, but what I have to do to get that output for every source code file in the Linux Lernel as part of the compilation process?
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FDT (Flattened Device-Tree): Property name (strings): Comma terminated string...
I have started to write a library (libFDT) for reading FDT (DTB) format files, but run into a problem with a test DTB file. The DTB file is form a board (Digilent ZYBO-Z7) which I own. I compiled the...
View ArticleAlternative to the GPL *find_symbol* method in Linux kernel module
I have a proprietary Linux module which might be loaded before or after a second proprietary module that contain the function foo.I would like my first module, when being configured dynamically, to...
View ArticleHow can I implement a driver for my external peripheral in kernel space?
I am using an orange pi zero which runs on armbian. I want to write a module in the kernel space as a driver for my external module (SPI interface). I have built the module with some gpios such as...
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Having Angstrom build and Poky build in one repository
I have successfully made a test image (core-image-minimal) for Colibri-imx6 board using the poky distribution. The kernel does not completely load when the image is deployed on the board. So, I have...
View ArticleWhat is the interface for ARM system calls and where is it defined in the...
I have read about system calls in Linux, and everywhere description is given regarding x86 architecture (0x80 interrupt and SYSENTER). But I am not able to track down the files and process for a system...
View ArticleWhy signals are platform-dependent in Linux?
SIGNAL(7) man page states:The numeric value for each signal is given in the table below. As shown in the table, many signals have different numeric values on different architectures ...Indeed. In Linux...
View Articletracing a linux kernel, function-by function (biggest only) with us timer
I want to know, how does the linux kernel do some stuff (receiving a tcp packet). In what order main tcp functions are called. I want to see both interrupt handler (top half), bottom half and even work...
View ArticleEasiest way to use DMA in Linux
I'm a EE and for a project at uni I'm developing hardware assisted image/video filtering on an FPGA (Xilinx ZYNQ), said device also has a dual core ARM A9 processor inside and more importantly there is...
View Article‘getnstimeofday' is an implicit declaration in system call when is included
AnwserSolved!! Thanks to @IanAbbottthe header should be:#include <linux/ktime.h> #include <linux/timekeeping.h> rather than <linux/time.h>.More detail see discussion.Original...
View ArticleIncrease tx power in WPEA-121N Wifi Card
I trying to increase tx-power on WPEA-121N Wifi Card (Atheros AR9382 Chip) but i just cant set it over 18 dBm. Inside datasheet specification i can see that power consumption for continue TX is 600mA...
View ArticleWhere is the kernel symbol __tracepoint_module_load defined?
Where is the kernel symbol __tracepoint_module_load defined? I saw it once in /proc/kallsyms, but now I can't find it.bootlin.com/linux/ cannot find it, either.
View ArticleDelay in linux socket communication
I have a userspace application (no access to source code) that sends CAN bus data using socketcan APIs.While sending the data of 64 bytes the application its facing a delay of 2 seconds between...
View ArticleWhy can't set the irq 's trigger type in Linux kernel?
I am working a problem in Linux kernel 3.18.20 with RTAI Patch 5.2. I found the frequency of interrupt which my driver had registered was high, about 20us/time.I tried to change its trigger type to see...
View ArticleWhat is the difference between T and t in /proc/kallsyms
This is a part of text file from System.map and /proc/kallsyms. ffffffff8106c260 T leave_mm ffffffff8106c340 t do_flush_tlb_all ffffffff8106c390 t flush_tlb_func ffffffff8106c510 T...
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