kernel

问题 I was debugging high System CPU usage (Not user CPU usage) on of our storm supervisors (Wheezy machine). Here are the observations Output of perf for the relevant process: Events: 10K cpu-clock 16.40% java [kernel.kallsyms] [k] system_call_after_swapgs 13.95% java [kernel.kallsyms] [k] pvclock_clocksource_read 12.76% java [kernel.kallsyms] [k] do_gettimeofday 12.61% java [vdso] [.] 0x7ffe0fea898f 9.02% java perf-17609.map [.] 0x7fcabb8b85dc 7.16% java [kernel.kallsyms] [k] copy_user_enhanced

问题 I want use task_for_pid() and attach to another process and then change its memory on iOS system. I could do it successfully on OS X with the help of authorization services API, but on iOS, task_for_pid() always returns KERN_FAILURE . I need to get task_for_pid() function to work on jailbreak iPhone under root. As discussed in “Authentication” iOS does not provide this API, What should I do? Could I run as root on iOS Simulator and how to test app required running as root? 回答1: It is

问题 I am working with time-critical applications where the microsecond counts. I am interested to a more convenient way to develop my applications using a non bare-metal approach (some kind of framework or base foundation common to all my projects). A considered real-time operating system such as RTX, Xenomai, Micrium or VXWorks are not really real-time under my terms (or under the terms of electronic engineers). So I prefer to talk about soft-real-time and hard-real-time applications. An hard

问题 I want to run a set of docker containers but with a custom kernel. Since Docker for Windows is already using Hyper-V, could it be possible to change which image is running? 回答1: I'm not familiar with Windows. But the Kernel that your VM is running is the Kernel that is used for all your Docker containers. So, my naive guess would be, changing the VM's Kernel would work. I'm assuming Hyper-V is the hypervisor. That would create a VM (running a Linux Kernel) on top of which the Docker

问题 I want to run a set of docker containers but with a custom kernel. Since Docker for Windows is already using Hyper-V, could it be possible to change which image is running? 回答1: I'm not familiar with Windows. But the Kernel that your VM is running is the Kernel that is used for all your Docker containers. So, my naive guess would be, changing the VM's Kernel would work. I'm assuming Hyper-V is the hypervisor. That would create a VM (running a Linux Kernel) on top of which the Docker

问题 While I was doing some reading on system calls, I did a search for syscalls.h to find the header file in LXR. The search results puzzled me. There is a dozen of syscalls.h files coming from directories under arch/_arch_name_/include/asm . These are ok, they are architecture specific definitions or something else needed. The question is why do we have two different syscalls.h headers under both include/linux and include/asm-generic ? Also, I want to find out that what include/linux headers are

问题 While I was doing some reading on system calls, I did a search for syscalls.h to find the header file in LXR. The search results puzzled me. There is a dozen of syscalls.h files coming from directories under arch/_arch_name_/include/asm . These are ok, they are architecture specific definitions or something else needed. The question is why do we have two different syscalls.h headers under both include/linux and include/asm-generic ? Also, I want to find out that what include/linux headers are

问题 I wanted to show to somebody an exemple of incorrect memory access (kernelspace trying to access userspace memory leading to a bug). Thus, I took an old tutorial as a POC, the important part is : static ssize_t dev_write(struct file *filep, const char *buffer, size_t len, loff_t *offset){ sprintf(message, "%s(%zu letters)", buffer, len); // appending received string with its length // [...] } This causes a crash in one of my environment tests, which is the expected behavior (I access the

问题 I wanted to show to somebody an exemple of incorrect memory access (kernelspace trying to access userspace memory leading to a bug). Thus, I took an old tutorial as a POC, the important part is : static ssize_t dev_write(struct file *filep, const char *buffer, size_t len, loff_t *offset){ sprintf(message, "%s(%zu letters)", buffer, len); // appending received string with its length // [...] } This causes a crash in one of my environment tests, which is the expected behavior (I access the

问题 i want to install the drivers for u are u 4500, but it only can be compiled with old kernel versions (2.6 to 3.2) , can you help me to install the drivers on ubuntu with last kernel version. The sample application of fingerprint cant recognize the device. 回答1: I am not sure what problems you are having, but I could compile and install the driver under Ubuntu 18.04. I did get a few errors during compilation, which I fixed as follows: Error 1: /opt/DigitalPersona/urusdk-linux/Linux/drivers