Can the spin lock deadlock when its interrupted from another CPU while...
I was reading about how spin locks for hardirqs vs softirqs.This is the docs:https://www.kernel.org/doc/htmldocs/kernel-locking/hardirq-context.htmlI understand that local interrupt is disabled to...
View ArticleExtract linux kernel from uImage for qemu use
I have the uImage file, boot-args and boot log of an embedded cortex-a9 device.When I specify the -kernel uImage qemu just hangs. The uboot tools say the kernel is uncompressed.What is the proper way...
View ArticleQEMU kernel for raspberry pi 3 with networking and virtio support
I used the QEMU(qemu-system-aarch64 -M raspi3) for emulating the Raspberry pi3 with the kernel from the working image. Everything was working but there was no networking.qemu-system-aarch64 \ -kernel...
View Articleattempting to install new kernel, error modules.order & Makefile Error 2
Attempting to install a new kernel.once it is compiled, I enter:su -c "make modules_install install"this error populates : sed: can't read modules.order: No such file or directorymake[1]: ***...
View ArticleHow is data really exchanged between user and kernel space while...
I'm writing my first trivial device driver and got a few questions:I'm following this book but doesn't seem like it goes into the details of the working while copy_(to|from)_user() API (or any APIs...
View ArticleHow is x0 register set for arm64 kernel start when ACPI table is used instead...
The head.S file for arm64 (arch/arm64/kernel/head.S) assumes that the x0 register contains the address of the device tree (dtb, or FDT).But some systems use ACPI table for handing hardware...
View ArticleIs linux directory system a part of the linux kernel?
Linux has a unique directory system such as /sys /usr /media /opt etc. I would like to know is this directory system is a part of linux kernel or has to be installed as an image later on once kernel...
View ArticleeBPF: printing UDP payload and source IP as hex
I am new in eBPF and want to learn how to do a few basic things. My question is how to write in the C code for my eBPF code in order to print (bpf_trace_printk) the UPD payload of an obtained packet in...
View ArticleIs there any way to have my laptop run Windows 10 while having a...
Before I start, I should let you know that my knowledge I have gained so far consists of self-study, so I might not get the correct terminology.I use Windows 10 for all of my productivity work, but I...
View Articlewriting a linux kernel module / driver for an old keyboard / hid device
I have an old Compaq keyboard that has a set of keys on top that do not work.I have tried xev, evtest, evemu-record and libinput debug-events and every other key except those keys is recognized.However...
View ArticleBPF hashmap not showing correct value when retrieving
I'm trying to create a hashmap in BPF in kernel code, as follows:struct bpf_map_def SEC("maps") hash_map = { .type = BPF_MAP_TYPE_HASH, .key_size = sizeof(__u32), .value_size = sizeof(__u32),...
View ArticleWhy is memory barrier not required for UP? [duplicate]
I am reading Linux Kernel Development 3rd edition by Robert Love,On Ordering & Barriers, I read that:smp_rmb() Provides an rmb() on SMP, and on UP provides a barrier()I do not understand why UP...
View ArticleLogging independent of /var/log/messages [closed]
If I understand correctly, we do store OS syslogs in /var/log/messages. I need to export the OS syslogs from this file to a central logging agent running on all the K8 nodes. Is there any way out where...
View Articlemulti-monitor layout/detection not persistent (docking, displaylink, kde)
Context :I have a dock labelled DisplayLink, 4HDMIorDP (actually DVI under the hood) to USB-C PD charging. So I use it with 4 external monitors and the internal monitor. I'm running Kubuntu20.04, on a...
View ArticleSimulating a process stuck in a blocking system call
I'm trying to test a behaviour which is hard to reproduce in a controlled environment.Use case:Linux system; usually Redhat EL 5 or 6 (we're just starting with RHEL 7 and systemd, so it's currently out...
View ArticleHow do I display syslog messages to the user using a C program?
Using syslog() the logs go to /var/log/syslog but I want to store those logs in a different file which can be displayed to a user as a daily log fileHow can i do that?
View ArticleDriving a 137,930 KHz 1080x1920 portrait HDMI screen from an IMX8M
I need to make a fixed-frequency screen (with a new custom mode line):{ DRM_MODE("1080x1920", DRM_MODE_TYPE_DRIVER, 137930, 1080, 1140, 1150, 1185, 0, 1920, 1928, 1932, 1940, 0, DRM_MODE_FLAG_NHSYNC |...
View ArticleeBPF: modifying UDP payload and responding to client
I'm trying to modify the UDP payload I receive from the client to clone and redirect the packet in order to respond to it. Swapping the MAC and IP addresses is already done, as well as the cloning, but...
View Articlekernel stack and user space stack
What's the difference between kernel stack and user stack? Why kernel stack is used? If a local variable is declared in an ISR, where it will be stored? Does each process has its own kernel stack? Then...
View ArticleLinux Directory System | Kernel Binding
Linux has a unique directory system such as /sys /usr /media /opt etc. I would like to know is this directory system is a part of linux kernel or has to be installed as an image later on once kernel...
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