Why do files created during runtime get deleted after rebooting in android?
I am creating a directory using mkdir /xxx/yyy 0771 system system in the init.rc.Now that the directory has been created, I am creating a file inside the /xxx/yyy-directory and place some context...
View ArticleWhich type page is prefered when kmalloc is invoked with the argument of...
Which type page is prefered when kmalloc is invoked with the argument of GFP_KERNEL solely, unmovable, reclaimable or movable pages? And could you please tell me your reasons?I think maybe it's...
View Article$(modules:.ko:.o) Advanced Features for Reference to Variables
I can't understand Grammar of makefile_modpost: $(if $(KBUILD_MODPOST_NOFINAL), $(modules:.ko:.o),$(modules)),when i browse kernel in scripts/Makefile.modpost at...
View ArticleWhy do movable pages of normal zone decrease rapidly when invoking...
Why do movable pages of normal zone decrease rapidly when invoking __vmalloc(80MB,GFP_KERNEL|__GFP_ZERO,...) repeatly?Why does not it use the memory of other types,e.g.: unmovable pages, movable pages,...
View ArticleZerocopy TCP message sending from kernel module error EFAULT
I am working on a kernel module which receives data over DMA from an FPGA and stores it in a ring buffer allocated with dma_alloc_attrs(dev, size, &data->dma_addr, GFP_KERNEL,...
View ArticleExtract vmlinux from vmlinuz or bzImage
I want to generate System.map from vmlinuz,cause most of machines don't have the file System.map.In fact,vmlinuz are compressed to vmlinuz or bzImage.It's any tool or script can do this?I tried:dd...
View ArticleCan I draw the conlusion that vmalloc calls kmalloc to allocate each page...
As per the article(https://www.oreilly.com/library/view/linux-device-drivers/0596005903/ch08.html), which says that[emphasis mine]:One minor drawback of vmalloc is that it can’t be used in...
View ArticleIs there a way to block system calls from a specific program in linux? [closed]
For example let's take firefox , Is there a way to make kernel ignore the syscalls from firefox so that when i try to run firefox it doesnt execute or do anything.
View ArticleHow to pass compiler options during Linux kernel compilation?
For reasons, I need to compile the Linux kernel (currently 4.7.10) passing some simple and innocent additional command line options (e.g. -pipe -Wsomething etc) to the C compiler.How do I do it?More...
View ArticlePXE boot fail with kernel panic: Unable to mount root fs
I am having an issue on some servers since some time, and fail to find the issue.These are x86_64 server, with Intel Xeon, configured to boot in UEFI over network, through an iPXE rom.Kernel and...
View ArticleUbuntu Linux PCIe aer-inject tool issues
I'm using a custom compile kernel (Version 4.15.0-108-generic #109-Ubuntu) to enable PCIe AER errors on my system. To verify AER is working, I want to inject AER errors from software using the...
View ArticlePCI Express AER Driver issues on Linux
I'm debugging a PCIe hardware issue on Linux and I want to enable PCIe AER driver on linux to catch any AER errors reported by my hardware device. I'm following this...
View ArticleRead data from file (as arrays) lines and do a comparison
I have an issue and no idea which solution is better to use, I will describe my need first in order to explain it to you :I have a text file, titled with a server name, example : server1.txtInside this...
View ArticleInstall OV7251 driver in RPI-3B+ to use with ROS
Hi all, I wanted to install the OV7251 camera driver to work with a module I've recently purchased, the Arducam OV7251 MIPI, as I need to perform SLAM-like system called Virtual Inertial Navigation...
View ArticleHow do you comprehend "vmalloc have to remap the buffer space into a...
How do you comprehend "vmalloc is often slower than kmalloc, because it may have to remap the buffer space into a virtually contiguous range. kmalloc never remaps, though if not called with GFP_ATOMIC...
View ArticleHow to store a value in the kernel hashtable [duplicate]
I am trying to use a hashtable in my kernel module.However, I don't really understand the API. The hash_add(hashtable, node, key) macro lets me insert a struct hlist_node element, where the struct is...
View ArticleWhy are there so many free movable DMA32 blocks on the x86 64bits platform?
Why are there so many free movable DMA32 blocks on the x86 64bits platform?As its name, I think it is used for DMA. But 730 free blocks(with order 10) means more than 1GB memory. How huge the memory...
View ArticleWhy is it not possible to link shared libraries into kernel code?
What are the implications? Is the kernel compiled with static libraries or are they implemented intrinsically?Also, according to this, kernel code cannot use any floating point operation. Why is that?
View ArticleIs Exception Vector a better name for Interrupt Vector? (in context of ARM)
I've understood the difference between an interrupt and an exception but I'm not able to understand the difference between an exception vector and an interrupt vector.What I found after doing some...
View ArticleClik here to view.
How to use the kernel hash table?
I'm trying to understand and use the kernel hash tables and I've already read this and this link, but I didn't understand none of them. My first question is: Why our struct has to have the struct...
View Article