How to use setfattr UNIX command to set access permission for other users to...
Studied about xattr from below link:[http://man7.org/linux/man-pages/man7/xattr.7.html][1]/home/testuser1# ls -l total 8 -rw-r--r-- 1 testuser1 testuser1 21 Nov 22 19:47 test_file -rw-r--r-- 1...
View ArticlePintos kernel panic with qemu
I try load pintos with Project1 (src/threads), but I got constantly rebooting. When I run pintos -- run alarm-single I got message:qemu-system-x86_64 -hda /tmp/FuGmf6tzW8.dsk -m 4 -net none -serial...
View ArticleCould a custom syscall access another process' memory?
Does the Linux kernel have any API to access another process' memory, given it's PID and memory address?For educational purposes, I've managed to create a custom syscall that just prints a message in...
View Articleps aux hangs with call_rwsem_down_write_failed when running docker container...
All, I run a java application container with resource limit, as lots of oom kill events happen every 2 or 3 minutes, then execute ps aux, the command hangs. this problem is easy to reproduced when run...
View ArticleISA Memory below 1 MB does it exists
From Linux Device Drivers Book:One of the most well-known I/O memory regions is the ISA range found on personal computers. This is the memory range between 640 KB (0xA0000) and 1 MB (0x100000)....
View Articlehrtimer state gets changed, and getting crash while accessing it via user...
I have taken the Software-based serial port module code from here and implimented it for my application for the iMX-6 processor. Although my driver is working fine to send/receive data between...
View ArticleIPTable Packet forwarding
Im just playing around with iptables , to forward packet to different server/port . I wanted to forward packets of port 8990 to different ip address 10.209.4.203:27017 . But it doesnt behave as...
View ArticleIssue in booting Xen DomU Linux
I am trying to run Mainline linux kernel v5.4.0-rc3 as DomU. My setup details below.Target hw: Pine64+ Architecture: aarch64 (arm64) Xen version: 4.6.5 Dom0: Mainline linux Kernel v5.4.0-rc3 DomU...
View ArticleHow the util of iostat is computed?
iostat -x -d can display many i/o statistic info. For util of iostat, the explanation is : Percentage of CPU time during which I/O requests were issued to the device (band-width utilization for the...
View ArticleNot able ping and ssh in linux 18.4
I have i9 server with two Ethernet ports, but HDMI port is in graphic card. I added static ip to one of the Ethernet port. With HDMI card am able to ping and make a ssh, but when I remove the HDMI card...
View ArticleHow to enable etnaviv drivers without using Yocto build?
I have custom board with kernel 4.14 and vivante drivers 6.2.4p4.0 (Official Freescale's ones). I want to test my Qt application using the mesa drivers instead of the Freescale's. I've already...
View Articlewhich linux kernel code create /dev/sda or /dev/sda1 for SATA device?
Someone told me udev create /dev/sda device when SATA device is detected. But as I read or understand udev. udev can run program or add symblink but can not create device /dev/sda.Image related to...
View ArticleYOCTO Change kernel version and select drivers
I am trying to compile a new Linux kernel obtained from https://github.com/qoriq-open-source/linux (version 4.9) for T1042D4RDB-64B embedded board using Yocto. It's currently using 4.1.35-rt41.I...
View ArticleLinux kernel synchornization mechanisms in user space
I know that in the Linux kernel, they have implemented their synchronization mechanisms, like futex and etc. I want to know, are there any substantial differences between synchronization mechanisms...
View ArticleDoes sigwait() behave differently in macOS and Linux?
I found the following code works differently in macOS and Linux:#include <signal.h> #include <unistd.h> #include <stdio.h> void catcher( int sig ) { printf( "Signal catcher called for...
View ArticleFunctionFS stalls endpoint when alternate setting is activated with...
I'm trying to create a Gadget using FunctionFS and the FS driver. My gadget is composed of two functions with the following configurations:Function 1: Interface 0: Endpoint BULK OUT 0x01 Endpoint BULK...
View ArticlePassing value to modified syscall function gets changed
I am trying to pass uid_t value as a parameter to modified syscall function (set_uid) and when I pass 30 from caller function, the value gets changed to random number such as 2154135383.This is...
View ArticleDebugging Android kernel: Passing arguments to android kernel while booting
I am trying to get kgdb working with Android kernel using http://bootloader.wikidot.com/android:kgdb. I got stucked at following step: Configure kernel command line Specify ttyGS0 as the kgdboc device....
View ArticleWhat is the relationship between framebuffer, VT, and tty?
I'm now studying what is the mechanism behind Ctrl+Alt+F1~F7.I found some infomation talk about framebuffer, VT, and tty. I know framebuffer is an anstraction to graphic card manipulation and tty(and...
View ArticleNesting of rcu_read_locks
I store a RCU protected pointer MyStruct *, in a RCU protected hashtable MyHash. When reading/updating MyStruct via hashtable, I do as shown below.rcu_read_lock() /* For hashtable 'MyHash' */...
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