tcp receive window increases and exceed the value negotiated during...
To understand what determines the initial value of tcp receive window, I run a simple test. First, launch a dumb server which accepts connection but doesn't read any data from the connection.Second, a...
View Articlelibpcap not filtering VLAN packets correctly, ignoring VLAN (0x8100) or...
I am using libpcap 1.9.1 to capture packets in combination with custom kernel (4.9.0).While googling and analyzing the strange behavior, I came to the conclusion that kernel removes (why?) 0x8100 or...
View ArticleWhere to report a possible bcm63xx usb kernel bug? [closed]
I'm using openwrt on a bcm6318 router (bcm63xx arch), and having a problem with the usb port.This is the original thread:https://forum.openwrt.org/t/rt2800usb-wifi-driver-problem/59917Where and who...
View ArticleIntel Onboard-LAN I217-V | e1000e kernel module not loading driver | ubuntu...
Expected result: Using onboard LAN, not using USB-tethering from phone.Actual result:Days of trying to figure out why the onboard lan broke and why it won't load/bind the driver from the kernel...
View ArticleWhy does this dereference to file_operations happen this way?
I am referencing this article and I am confused about this bit of code here: /* get a copy of file_operations from inode */ proc_fops = *proc_inode->i_fop; /* backup the file_operations */...
View ArticleHow to give root permission to a module?
I'm working on a module that when I call echo "hello"> /dev/filename I get bash: /dev/filename: permission denied. For me to get permission I have to call sudo chmod 666 /dev/filename and then echo...
View Article/proc/acpi/ibm folder don't exists [closed]
I installed Kali Linux 2019.4 in k550vx-E Laptop (Asus), But /proc/acpi/ibm/ folder don't exists!In Oder Linuxs i can see it but it don't exists on my lap top.I know this folder at linux systems use...
View ArticleWhere does task_struct get initialized in the Linux kernel?
Is there a function that gets called to initialize (at least some) values of task_struct? Or is there any other function that gets called upon task (specifically, user-space process) creation?
View Articleis it possible to know whether a network device connected or not through...
I am working on a router. I have to know which network devices are connected and which are disconnected from my router. I read /proc/net/arp and check the value of flag field. If the value of the flag...
View ArticleHow can this function do "write" operation without writing in "Transmitter...
Here's the code from rt_imx_uart.c :static ssize_t rt_imx_uart_write(struct rtdm_fd *fd, const void *buf, size_t nbyte){ struct rt_imx_uart_ctx *ctx; rtdm_lockctx_t lock_ctx; size_t written = 0; int...
View ArticleHow Poll/Select System Call Know That Which Event Occur?
I am trying to understand how poll/select system call works internally?I read in John Madieu's Linux Device Driver Development book that wait queue can be notify with wake_up_interruptible function.But...
View ArticleUser space interrupt handler
When a user space interrupt handler is hooked-up several interrupt sources via uio_pci_generic driver in Linux, is it required that the user space interrupt needs to do serialization? Additionally,...
View ArticleFile replacing in linux kernel
I need to replace a file with another one on a VFS (having both struct file) in a Linux kernel module. I tried 2 ways of doing that but both have some problems.So I have 2 files correctly initialized,...
View ArticleWhy my LKM is killed when i insert the modeule
(In VM workstation, Linux, ubuntu)This is my whole code. I don't know why my LKM is killed when I insert module(insmod).I checked all the functions and there is no error message when I did make.Please...
View ArticleWhat format should I obey when I pass string into kernel_sendmsg?
Recently, I'm modifying some socket program in kernel space. Following is basic server sending function:static int http_server_send(struct socket *sock, const char *buf, size_t size){ struct msghdr msg...
View ArticleError building latest linux kernel within VirtualBox under 18.04.1-Ubuntu
I am trying to build the latest Linux kernel (GitHub) using a Oracel VM and a 18.04.1-Ubuntu image.I installed the need packages and probably even more. Here is a part of the packages I installed:sudo...
View ArticleHow I can include the /kernel/sched/* into a BPF program?
I am trying to make a custom bpf program with bpftrace in Linux, according to the book BPF Performance Tools. I tried to include some files from the path linux/kernel/sched/sched.h. How can I include...
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What are the factors that effects the kernel build(Image) to flash on the...
I have fully unlocked the Samsung device and I have downloaded the Kernel sources from the Samsung open-source site. I have built the kernel fine with instructions are given in the README_Kernel.txt...
View ArticleHow to get mount point for a given path in custom linux kernel module
As the title says I have a problem with my custom kernel module. My goal is to retrieve the root mount point of a given path. Just like using df:df "/tmp/some_dir/some_file"vvvvvvvv out...
View ArticleWhat is the purpose of the /usr/src/linux/drivers directory?
From what I googled (link) /usr/src/linux should contain the source code of linux and its header files, but the directory drivers (for example, more specifically...
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