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Questions tagged [userspace]

109 questions
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Linux tool to send a SET_CONFIGURATION message to a device connected to the USB bus

I have developed a kernel driver for a USB device. Such a device has some pins that can provide functionality both as CDC ACM serial port or as input buttons. So to implement that I had to use two different USB configuration descriptors. The driver…
aicastell
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How user virtual address access the physical memory , if all the memory is mapped directly with kernel virtual address

If we have a 32bit CPU, it can have 4GB of virtual address space. the first 3GB ( 0- 3GB) is for user space virtual addresses and rest 1GB ( 3GB - 4GB) is for kernel virtual addresses. But as I can read in many articles , and even in LDD book ,…
Puneet Gupta
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Passing parameters to custom syscall in unix

I am attempting to create a custom system call that inputs an (long) array and outputs some basic information about this array for a class assignment. I am having some trouble passing the appropriate arguments into the system call. Below is the test…
Wahotaho
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Kernel module starting userspace application from docker

I have a Kernel module program which executes an userspace app named binary as shown below. struct subprocess_info *info; static char *envp[] = { "HOME=/", "TERM=linux", …
Sriram.K
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File System in Userspace (FUSE) compilation error

/*This is a simple try to create a File System in UserSpace The pre_init function just initializes the filesystem */ #include #include #include #include static void* pre_init(struct fuse_conn_info…
vignesh_md
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Which are the ways to redirect the execution flow, from user-space to kernel in x86_64?

I know two ways to redirect the execution flow, from user-space to kernel in x86_64: 1. SYSCALL Service 2. Software interrupts Is there any other way to go into kernel from user-space? Any help would be appreciated.
Puffy
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How is it possible to update the firmware from userspace?

This is one of those things that has always blown my mind. How is it possible that when I am logged into windows I can run an application that allows me to upgrade my devive BIOS or install firmware for my hard disk and etc. I have not found any…
ng.newbie
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Including Drivers in User Space Programs/ SPI Application

Right now I am looking to use the Cadence SPI driver to perform some basic reading and writing on Linux. I have just used the I2C driver, but I am still a little confused as to how all of these drivers fit together and if there is a general…
John Frye
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linux syscall using spinlock returning value to userspace

I'm, currently struggling with the correct implementation of a kernel-spinlock in combination with a return statement which should return a value to userspace. I implemented a kernel syscall 'sys_kernel_entropy_is_recording' which should return the…
OliverJL
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free(): invalid pointer only after zerocopy DMA driver access

I have a driver that does a DMA transfer to a memory thats malloc'ed in a userspace application and then handed down to the kernel (get_user_pages...). Problem: I get the "invalid pointer" message when calling free(). I print both pointer values,…
Thomas S.
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how to create *.a to *.so in linux user-space?

i done compile file makefile.am and i need shared link for my lib, for example after compile i see /usr/lib64/libtest.a but i need libtest.so because i need my lib to other C source file, example :g++ -llibtest test.c i read about this here but i…
Ramin Farajpour Cami
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cross platform (mac/win) way to write uboot to specific location on sd card

I am working on a cross platform (mac / windows) updater tool to write an uboot SPL to a specific location on an SD card. I basically want to do the equivalent of this linux command, from my user space C++ application: sudo dd if=out of=/dev/sdb…
b20000
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How to send a simple message from kernel to user space?

I have a very simple (I think) problem. I have a very simple kernel module, which handling an interrupt coming from my hardware (its all described in my device tree). I get the interrupt in kernel. Now I want to send a message (just 64 Bit, two…
alabamajack
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How to change the batch size at NIC for DPDK application?

I am using intel 2P X520 Adapter on Xeon(R) CPU E5-2640 v3 based server running Ubuntu 16.04. I am interested in measuring the performance(throughput) of the application when we change the batching factor at NIC and in application. By changing the…
A-B
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When would one choose to write software in kernelspace rather than in userspace?

Let's say you have an embedded device (e.g. a raspberry pi) running embedded linux and want to communicate with an external module. In which cases would you decide to communicate with the device by writing a kernelspace driver? In which cases…
jithophipr
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