How to debug kernel code without running kernel?
I'm reading some kernel books, I want to debug the spinlock_t usage, and prepared the following demo code:////////////////////////////// demo/spinlock.c////////////////////////////#include...
View ArticleAbout the usage of "__GFP_COMP"?
I found nothing useful but only comment on __GFP_COMP throughout the source code of kernel, which says: "__GFP_COMP address compoundpage metadata."I googled it, but I'm still confused.Besides, I called...
View ArticleHow to calculate total RSS of all thread stacks under Linux?
I have a heavily multi-threaded application under Linux consuming lots of memory and I am trying to categorize its RSS. I found particularly challenging to estimate total RSS of all thread stacks in...
View ArticleHow does `do_new_mount_fc()` mount real file systems like ext4?
In relatively old Linux kernel source codes, the do_new_mount() will call vfs_kern_mount(), which will finally do mount_fs(). And this function will call the real file system's function like...
View ArticleWhat's different for ldconfig & modprobe
When I follow the zfs install guide in CentOS。I found out it should use ldconfig after finish the source building。But when I use the zfs command，it tell me, I should type command: /sbin/modprobe zfsSo,...
View ArticleCan a single pipe be used for 2 way communication between parent and a child?
Suppose I use pipefdn[2] and pipe() on it , can bidirectional communication be implemented using a single pipe or do you need 2 pipes ?
View Article"CANNOT USE STACK VALIDATION" error while compiling 'make' command in linux...
this is the problem comes whenever i am compiling kernel by using make command.Makefile:1092: "Cannot use CONFIG_STACK_VALIDATION, please install libelf-dev, libelf-devel or elfutils-libelf-devel"li...
View ArticleBuilding an Android Phone - what I need to know about drivers? [closed]
So I want to build Android phone on i.MX8 chip. I'll add various modules into the board like bluetooth, gsm, wifi. What will I need to do in order for it to work properly? Develop linux kernel drivers?...
View ArticleAbout linux v5.4 kernel arm64_memblock_init() / fdt_enforce_memory_region()
Q: What is the use of linux,usable-memory-range property? Background:Recently I am analyzing how Linux kernel initializes memory. When I go to arm64_memblock_init function in arch/arm64/mm/init.c, I...
View ArticleLinux Kernel Dev - cgroup - How to list tasks' id from a group?
I'm developping a kernel module and I'd like to be able to list tasks' id from a group.For example: I create two groups in the cpuset subsys: A and B. In B/tasks I put a PID. From my module, I'm...
View ArticleHow can I find out how many blocks memory of each order is allocated by buddy...
I know the way to find out how many free blocks are available on the current platform, e.g.:sudo cat /proc/pagetypeinfoPage block order: 9Pages per block: 512Free pages count per migrate type at order...
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 597 free blocks(with order 9) means more than 1GB memory. How huge the memory...
View ArticleDoes the value of moveable\unmovable blocks of zone normal got from...
Does the value of moveable\unmovable blocks of zone normal got from /proc/pagetypeinfo stay invariable after the startup of the kernel?I observed this file(i.e /proc/pagetypeinfo) for an hour, the...
View ArticleHow do you get the size of a file in the linux kernel?
I found this link (http://www.spinics.net/lists/newbies/msg41016.html) and have been looking into doing just that. So I wrote code in a kernel module:#include <linux/path.h>#include...
View ArticleMore info on arm64: unwind: remove sp from struct stackframe
In Linux kernel for ARM64, struct stackframe had a member "sp" but it was removed.As per upstream patch https://www.spinics.net/lists/arm-kernel/msg595534.html,"The unwind code sets the sp member of...
View ArticleWhy I can not control my embedded board GPIO pins using C# .NET core program...
I am using ARM SAMA5D27 SOM1 EK1 embedded board. I am using Linux 4.14 kernel.I have a problem with this board GPIOs and I don't know what is going on with them.First, I will show you the output of...
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How to use MPTCP included in linux kernel 5.6.x?
I am trying to use MPTCP that is included in linux-5.6.x. I assume this is a version of https://www.multipath-tcp.org/ but it does not seem to be the same.Does the in-kernel MPTCP correspond to any...
View ArticleManually compiled kernel fails to boot: stuck in initramfs prompt
I am trying to compile a custom kernel for my old laptop (it's a Dell Inspiron 1525, with a Core 2 Duo processor, 2GB of memory and a HDD -- not SSD). In this computer I have 3 partitions, 2 small ones...
View ArticleInotify write visibility guarantees
I'm confused if there are some ordering guarantees when working with inotify. For example: Process1 | |write(fd, void *, 8192) | | vsome.file ------- IN_MODIFY -------> Process2Is it guaranteed that...
View ArticleHow should DMA Engine continuous transfer be done?
This is an overview of how one might use the Linux DMA Engine to engagethe mainline Xilinx driver for its FPGA IP...
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