Questions tagged [interrupt]
The interrupt tag has no usage guidance.
139
questions
0
votes
1answer
38 views
Why does SIGINT not terminate a stopped process?
According to the POSIX standard regarding signals (see "Standard signals" section), both SIGKILL and SIGINT have as default action Term. However, this seems not to be the case when the ...
1
vote
1answer
38 views
How are big values stored in linux?
For example, cat /proc/interrupts.
I see this value is constantly growing -
36: 10273035 IPIC 36 Level eth1_g0_rx
What happens when it reaches its maximum value: that is the maximum ...
0
votes
1answer
48 views
Is it safe to restart system calls?
I was reading a textbook which describes how to deal with system call when interrupted:
System calls can be interrupted. System calls such as read, wait, and accept that can potentially block the ...
0
votes
0answers
39 views
Ctrl + C Not terminating a process in Linux
I am building a custom Linux Image using Yocto Zeus (5.4 Kernel). On loading and checking the various functionalities of the Image, I am not able to exit some of the processes such as ping, tail -f in ...
12
votes
1answer
256 views
Do system calls actually “interrupt” the CPU the same way that hardware interrupts do?
I'm trying to get a deeper understanding of how system calls and hardware interrupts are implemented, and something that keeps confusing me is how they differ with respect to how they're handled. For ...
2
votes
1answer
74 views
Hardware timer , Real time clock, Jiffies in Linux context
I am trying to understand the Timer interrupts and the associated terms used in an x86_64 Linux machine.
Hardware timer (External clock) is same as a Real Time Clock.
The Real time clock runs even ...
0
votes
1answer
64 views
Broken my pop-OS while upgrading
I mistakenly broke my pop-OS and when I restart it then I get an error window with
**Error occured which system cannot restored. Contact administrator**
I already tried apt-get dist-upgrade in ...
0
votes
0answers
50 views
What is meaning of empty action respect to /sys/kernel/irq?
Linux Kernel 4.9 version introduced the ability to expose interrupt information through sysfs. Documentation for this can be found here.
As we can see from documentation, there is a actions file ...
0
votes
1answer
42 views
__report_bad_irq not getting hit
I am stucked in one issue, in which i am getting __report_bad_irq callstack inconsistently.
AFAIK, whenever we have 100000 unhandled interrupts this stack kicks in.
Output from cat /proc/irq/128/...
0
votes
1answer
74 views
Handling an interrupt while being on kernel [closed]
I know how interrupt handling works (switching mode, saving registers, changing stack ...). However, I am curious, what if an interrupt happens while we are still in kernel mode, and not in user mode?
0
votes
1answer
47 views
redhat 7.7 nohz_full dynamic tickless behaviour
I'm trying to set dynamic tickless behaviour on certain cores (cores 2 - 11), moving all timekeeping to the only unspecified cores (cores 0-1). However, when I perform the instructions specified in:
...
4
votes
2answers
481 views
How interrupt is queued up in linux?
In hardware and software interrupt flow how queue up is handled? more precisely I have following doubts
Lets take a scenario I have a machine with 2 CPUs. CPU1 is processing process P1 and CPU2 is ...
2
votes
1answer
70 views
Is it safe to use the .bss section as a static stack?
(This is in the context of x86-64 Linux.)
I am trying to write a high-reliability userland executable, and I have total control over the generated assembly. I don't want to rely on automatic stack ...
1
vote
0answers
172 views
Custom interrupt handler for the NMI hardware button
I'm trying to create a custom interrupt handler for the NMI hardware button which exists on my motherboard.
To test this functionality I've created this simple module:
#include <linux/init.h>
#...
0
votes
1answer
27 views
Would an asynchronous interrupt context write to the page table in the Linux kernel?
Specifically, in the Linux kernel, is it possible that the page table (level3_kernel_pgt) can be overwritten when an asynchronous interrupt context happens (Local timer interrupts).
I've been seeing ...
0
votes
0answers
36 views
Interrupt pin routing changing
When I doing lspci, sometimes I found the interrupt routing is changed.
It may change from
Interrupt: pin B routed to IRQ 12
to
Interrupt: pin B routed to IRQ 13
What caused this change?
0
votes
0answers
25 views
How arbitration priority register works in Advanced Programmable Interrupt Controller (APIC)?
Could you please explain how arbitration priority register works in Advanced Programmable Interrupt Controller (APIC) and what is the term winning CPU?
0
votes
1answer
233 views
System interrupts. When is it too much?
We're testing Linux Server as a VPN router.
We have a quite good server and the interrupts we're experiencing right now are ~170k, but we're expecting more. CPU usage is OK. How to know when it's too ...
0
votes
1answer
42 views
Why we have so many 0's in intr field of /proc/stat
I am looking into intr field of /proc/stat.
# cat stat
cpu 10438 2056 25767 10098612 2490 0 1846 0 0 0
cpu0 1768 260 4750 1681597 119 0 608 0 0 0
cpu1 1735 67 5119 1683444 342 0 280 0 0 0
cpu2 1908 ...
0
votes
0answers
17 views
Can a process directly wake up and deliver message to other process?
Can a process directly bring back other process's context to CPU and deliver message to that process, with things like interrupt?
If the process, that I want to wake up and deliver message to, is ...
1
vote
0answers
184 views
Notify user-space about interrupt, sleep otherwise
As a beginner, I want to know what people think would be the best course of action for the following scenario. I have a driver that handles a rising-edge interrupt on a gpio pin. The driver also has a ...
3
votes
2answers
2k views
Linux timer interrupt
I have two questions about the Linux kernel.
Specifically, does anybody know exactly, what Linux does in the timer interrupt? Is there some documentation about this?
And what is affected when ...
4
votes
1answer
1k views
What is the hardware which the linux kernel uses for timer interrupt
I am reading about jiffies which will be updated for every timer interrupt. The frequency of the timer interrupt is determined by compile time constant HZ.
We have lot of hardware devices present on ...
6
votes
1answer
1k views
Interrupt child processes from bash script on Ctrl+C
I'm starting two child processes from bash script and waiting both for completion using wait command:
./proc1 &
pid1=$!
echo "started proc1: ${pid1}"
./proc2 &
pid2=$!
echo "started proc2: ${...
1
vote
2answers
1k views
How does a keyboard press get processed in the Linux Kernel?
I'm currently learning about the Linux Kernel and OSes in general, and while I have found many great resources concerning IRQs, Drivers, Scheduling and other important OS concepts, as well as keyboard-...
2
votes
0answers
651 views
Manjaro/Arch: Disabling IRQ #31 on Thinkpad X1 7th
I've stumbled upon the beforementioned error during boot and have tried to resolve it by trying to find out what caused the interrupt.
Sadly, lspci -v | grep 31 gives no result and a cat /proc/...
3
votes
1answer
374 views
What are the non-numeric IRQs in /proc/interrupts?
cat /proc/interrupts shows a bunch of IRQs such as NMI and LOC. The per-line comments in the output give clear explanation, but if they do not have a numeric IRQ number, how does the x86 CPU respond ...
2
votes
3answers
292 views
Dump contents of variable to file while script is running in bash
I have a lot of files in a directory:
$ ls
file000001
file000002
# ... truncated ...
file999999
I am calculating the md5sum of the files like this and finally dumping it to a file:
hashes=''
for ...
6
votes
1answer
2k views
How to deduce the nature of an interrupt from its number?
I'm trying to boot/install Linux for learning purposes, using an older PC (HP Pavilion Elite m9660de). The following message is the first thing that shows up when booting (Ubuntu and Fedora, both from ...
0
votes
1answer
223 views
How fast is an IO interrupt in Linux versus bare metal? (ARM, Raspberry Pi)
I read that an interrupt in Linux (this was about a Raspberry Pi) can take a "long time" to process or let's say "start doing what the programmer wants". Is that true and how bad is it?
Is there a big ...
2
votes
0answers
35 views
What mechanism is used by Linux (or hardware) to ensure that any interrupt capable device does not cause too many interrupts?
At the level of interrupts, one would think that there has to some way for a maximum rate to be defined. Otherwise, a malicious device might be able to slow down the system, by continuously giving off ...
0
votes
1answer
174 views
Redirecting all primary file descriptors using `exec` causes the shell to exit after program exists depending on which end closes the connection?
I've been practicing my Bash skills by creating reverse shells using various redirection operators.
After having set up a nc listener:
nc -lvp 4444
I run the following command:
0<&116-; ...
-1
votes
1answer
914 views
fatal error : linux/interrupt.h : no such file or directory
I am developing code for interrupt. When I am including #include <linux/interrupt.h>, I get
fatal error : linux/interrupt.h no such file or directory
Why am I getting this error and how can I ...
1
vote
1answer
54 views
Writing and Executing Program to behave like console
I have written a set of programs with the intent of using a radio transmitter-receiver (NRF24L01) to connect two devices as if they were connected via a serial interface.
Currently, i am able to ...
4
votes
1answer
1k views
What's the policy determining which CPU handles which interrupt in the Linux Kernel?
I've been reading Linux Kernel Development and there's something that's not entirely clear to me -- when an interrupt is triggered by the hardware, what's the criterion to decide on which CPU to run ...
1
vote
0answers
47 views
Trouble with Legacy interrupts on new CPU
A legacy (IntA) interrupt works on an old CPU under Linux, but fails under the same Linux OS with a newer CPU in that system. I'm unsure if the problem is in the BIOS or in the Linux driver, as both ...
6
votes
2answers
15k views
What is interrupted system call?
I am reading APUE and the Interrupted System Calls chapter confuses me.
I would like to write down my understanding based on the book, please correct me.
A characteristic of earlier UNIX systems ...
1
vote
0answers
250 views
Trying to use local APIC timer
I'm trying to use the local APIC timer to send interrupts after a certain interval (for a kernel module I am writing). This is not related to scheduling in Linux.
I set the clocksource in Linux to ...
1
vote
1answer
1k views
How does Linux Kernel switches from kernel stack to interrupt stack?
What happens when a user mode task is interrupted ?
I know for a fact that the CPU switches to the kernel mode stack by refring the TSS.
But when and how does the kernel switches to the IRQ stack?
0
votes
1answer
710 views
About IRQF_DISABLED flags
I'm reading about a tutorial on request_irq, I'm new to this topic so I need some idea checking:
When set, this flag instructs the kernel to disable all interrupts when executing this interrupt ...
1
vote
1answer
138 views
Resource locking in interrupts
I have a kernel module with netfilter hooks at different points in the packet route, and the hooks use shared resources. In addition, the module has a char device that may be written to, that also ...
0
votes
2answers
64 views
Are interrupts used to signify that output is ready or input has completed?
Operating System Concepts says:
During I/O, the various device controllers raise interrupts when they
are ready for service. These interrupts signify
that output has completed, or
...
0
votes
0answers
407 views
Interrupt signal names don't work over ssh: bad trap [duplicate]
If run over ssh, a script with a trap statement with interrupt signal names (SIGINT, etc) gives an error and the trap does not work when an interrupt (eg. Ctrl+C) is sent. Eg:
#!/bin/bash
trap '...
4
votes
1answer
412 views
How to ignore interrupts with piped commands
In the following chain of piped commands, when an interrupt is sent with Ctrl-C, ping is able to print its summary statistics before exiting, as long as tee has the -i (ignore interrupts) flag:
ping -...
1
vote
0answers
432 views
how to use ftrace to function_trace a kernel modules interrupt?
I have a Banana Pi Arm device with 2 cores (1.2 GHz) running a Debian kernel which I enabled ftrace kernel debug options. I want to determine the amount of time spent in a kernel module function. The ...
1
vote
1answer
633 views
How does the kernel scheduler know a timeslice has passed?
In my previous question How does the kernel scheduler know how to pre-empt a process? I was given an answer to how pre-emption occurs.
Now I am wondering, how does the kernel scheduler know that a ...
2
votes
2answers
993 views
How does the kernel scheduler know how to pre-empt a process?
As far as I understand, the kernel is not a process, but rather a set of handlers that can be invoked from the runtime of another progress (or by the kernel itself via a timer or something similar?)
...
0
votes
0answers
167 views
Why does nohup command interrupt?
I put a command in .bash_profile file. The command is:
nohup stdbuf -oL -eL sysdig -c spy_users 1>>/path/to/out 2>>/path/to/err &
While I am working on terminal it appears:
[1]+ ...
3
votes
0answers
210 views
Is there a way to route interrupts from two Ethernet interfaces to separate cores?
I have a 10G ethernet adapter from Intel with two ethernet ports (x550-T2) installed in PCIe port of a Xilinx FPGA board running petalinux. I am testing network bandwidth by running simultaneous ...
1
vote
1answer
2k views
can't change value in smp_affinity
I am trying to set irq affinity on linux by changing the value in smp_affinity. When I echo the new value into the file, I don't get any error but when I read it back, the value remains unchanged. I ...
