Modifying fork.c file in kernel to print a customised message when fork() is...
I am trying to print to the system log the process ID of the child process as well as my name. I have tried using printk and displaying the messages with dmesg, but the message that I print does not...
View ArticleIs there a way to lookup refcount for a kobject?
I expected to find a function along the lines of kobject_check_refcount, that returned the current refcount without altering it, in kobject.c, but as far as I can see there isn't one. Is there such a...
View ArticleUsing wait_event_interruptible and wake_up_all together
For a class project involving scheduling processes using blocking and locks, we're supposed to use two kernel functions:int wait_event_interruptible(wait_queue_head_t q, CONDITION);void...
View ArticleWhen signal handler is not called when segment fault occurs?
Below is the operation method of my program, and there was a case where the registered handler was not called when the program was terminated due to the occurrence of a segment fault.Is there a case...
View ArticleSetting GPIO on boot before drivers [closed]
I work on IMX8MQ with a custom Yocto Linux image.I have a device that is controlled by a driver(not mine). The driver detects the device on boot and controls it via I2C.I have a need to turn the power...
View ArticleHow do I delete virtual interface in Linux? [closed]
ip link shows this:[root@0-25-90-68-79-4a log]# ip link1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:002: eth0:...
View ArticleHow to register user app to get notified with battery events(low, critical...
I am writing power supply driver(mypower_driver.c) which registers two power supply and implements couple of power supply properties like status, present, capacity etc.BatteryAC(Mains)I am using Yocto...
View Articledentry_path_raw ignoring the home directory
I wrote and lkm and I am trying to print the current dirctory but when i am on/homeit print only/and for example if I am at/home/danielit print only/danielbut if i am at /etc directory or any other...
View Article32-Byte PCIe transaction from Linux driver
I want to do 32 bytes transaction to/from PCIe device inside the Linux driver.Compiling Intel AVX instrinsics for Linux Device Driver with GCCCode:base_4 = ioremap(bar_data->bar_paddr[4],...
View ArticleHow often does Linux page replacement try to move pages from active to...
I am on Linux 5.6. My understanding is when a page fault occurs, Linux puts the new page into the active_list using lru_cache_add_active_or_unevictable() (with the exception of file-backed pages which...
View ArticleDisable reverse path filtering from Linux kernel space
Within a Linux kernel module, I need to disable rp_filter in some way.This would typically be possible from user-space via a couple of simple sysctl calls :sysctl net.ipv4.conf.all.rp_filter=0sysctl...
View Articleactive/inactive list in linux kernel
Where can I get active/inactive page lists inside Linux kernel which is maintained for memory management?Basically I want to dump these lists' info periodically, so I could understand which pages are...
View ArticleIs it possible to use gdb and nested qemu virtual machine to debug linux user...
I want to debug a user application running in a nested virtualization environment.So I build a static version of QEMU and run it with KVM support.I call the first VM running by QEMU as host VM, and...
View ArticleWhat does it mean to have a zero sized array of pointers?
I came across definition of a struct that looked something like this in the linux kernel sources (net/ipv4/fib_trie.c)-struct key_vector { t_key key; unsigned char pos; /* 2log(KEYLENGTH) bits needed...
View ArticleEditing the issue file in linux to display for a longer period of time before...
I'm a complete beginner in linux and I've been trying to get a message to show for a longer period of time (or being able to read an input) before the login screen, to do this I have to edit the file...
View ArticleReading memory to a file [closed]
I want to be able to write all memory from kernel and user space to a file. My machine is running Linux kernel version 4.18. Is there a straightforward way to read and write kernel memory?
View ArticleELF Header Magic - Why was 0x7F put in it?
Every resource I have read concerning the ELF header magic points out that it contains ASCII encoded "ELF", and then briefly mentions that 0x7F is prepended to it without explanation. Is there a reason...
View ArticleYocto project proble with qemu
after running source oe-init-build-env in poky(git of yocto) i run bitbake and i compile everything running smoothly after i do source oe-init-build-env i move into the right folder path and i do...
View ArticleWhere is this set of boot arguments coming from?
I'm using Yocto to port the EVL Core to an iMX6 Sabre SD board.I had an core-image-minimal of a kernel (apparently not mainline) that booted correctly with the following boot arguments being displayed...
View ArticleWhat happens to preempted interrupt handler?
I could not find a proper answer for the following questions even in some well written kernel books:They are saying that an ISR can't sleep because its not possible to reschedule an ISR as it is not...
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