I would appreciate if some one can explain me why the two files do not exist? How Android kernel’s virtual memory space and physical space be like without have the 2 files? Edit: I am having Android 2.3.7 (Cyanogen mod), the 2 files do not exist: Edit2: I have checked the Samsung Galaxy S3 running ICS, …
Tag: linux-kernel
Context switches much slower in new linux kernels
We are looking to upgrade the OS on our servers from Ubuntu 10.04 LTS to Ubuntu 12.04 LTS. Unfortunately, it seems that the latency to run a thread that has become runnable has significantly increased from the 2.6 kernel to the 3.2 kernel. In fact the latency numbers we are getting are hard to believe. Let me…
Distinguish forwarding traffic and locally originated traffic in Linux network driver
Is there any information in the struct skbuff to distinguish between the forwarding traffic (bridge forwarding and ip forwarding) and locally originated traffic? We want to treat these two kinds of traffic differently in the network driver because the forwarding traffic do not require cache invalidation on th…
How to debug the init_module() call of a Linux kernel module?
I am doing first steps into Linux kernel development. I have some code producing a .ko kernel module that I install with insmod. I would like a way to debug what happens when I install the module but I am facing some difficulties. I need to debug the call to init_module. Is this function called when I run ins…
Why is the close function is called release in `struct file_operations` in the Linux kernel?
I’m trying to make a linux kernel module, which supports open, close, read and write operations. So I want to register these functions via struct file_operations, however I can’t find ‘close’ entry in the struct. I think I should use ‘release’ instead of ‘close’…
How do I get the interrupt vector number on Linux?
When I run “cat /proc/interrupts”, I can get the following: How can I get the interrupt number of “NMI” “LOC” “SPU” “PMI”, etc. Answer On x86 NMIs are always on interrupt vector 2. The number is hard-coded just as common exceptions (division by 0, pa…
What’s the purpose of the UD2 opcode in the Linux kernel?
I have found the following fragment in the Linux kernel (not the corresponding C code though), somewhere during the start up phase. You can clearly see the 0F 0B parts, which stand for the UD2 opcode (IDA refused to disassemble). There are some possible usages for this opcode explained here and here. In this …
Linux readw and readl endianness
May anyone please explain the endianness of returned values by readw and readl. I am currently using PowerPC arch. Thanks and Best Regards! Answer “readw” and “readl” return the value of the underlying architecture. As it happens, a PowerPC can be either big- or little endian. AFAIK, m…
Linux SCHED_OTHER, SCHED_FIFO and SCHED_RR – differences
Can someone explain the differences between SCHED_OTHER, SCHED_FIFO and SCHED_RR? Thanks Answer SCHED_FIFO and SCHED_RR are so called “real-time” policies. They implement the fixed-priority real-time scheduling specified by the POSIX standard. Tasks with these policies preempt every other task, wh…
In what context Kernel Thread runs in Linux?
I am newbie to Linux Kernel. I know that there are two context 1. Process Context, running in user space or in Kernel Space (for ex: as part of System call) 2. Interrupt Context In what context Kernel Thread (not related to any User Thread, for ex:flush task) runs ? Is there any other context other than Proce…