What is the meaning of (OE+) in the following?
$ sudo cat /proc/modules | grep hello //hello_world is a kernel module created by me.
hello_world 20480 1 - Loading 0xffffffffc0221000 (OE+)
Here is my situation.
I have patched the Linux kernel function load_module(), which is called from finit_module(), the system call used by insmod to insert kernel modules.
The patch looks for a specific module, created by me (called hello_world) being installed, and when it does, it prevents the call to do_init_module(), and returns 0 instead. do_init_call() is responsible for calling a module's init function, and setting the module state to live (MODULE_STATE_LIVE).
When I read /proc/modules, the module state is Loading, which is expected. I do not understand however the meaning of (OE+) at the end of output. This is not displayed against any other module, as is verified by the following command.
$ sudo cat /proc/modules | grep OE
hello_world 20480 1 - Loading 0xffffffffc0221000 (OE+)
I am using Linux kernel v4.7.3.
Update
All this is happening in a Qemu virtual machine. On the host, which is running Linux 4.4.0-36-generic (Ubuntu), I get the following.
$ sudo cat /proc/modules | grep OE
vboxpci 24576 0 - Live 0xffffffffc082a000 (OE)
vboxnetadp 28672 0 - Live 0xffffffffc066e000 (OE)
vboxnetflt 28672 0 - Live 0xffffffffc0635000 (OE)
vboxdrv 454656 3 vboxpci,vboxnetadp,vboxnetflt, Live 0xffffffffc0783000 (OE)
sep4_0 671744 0 - Live 0xffffffffc06de000 (OE)
socperf2_0 36864 1 sep4_0, Live 0xffffffffc0660000 (OE)
pax 16384 0 - Live 0xffffffffc05f9000 (OE)
O means Out-of-tree module has been loaded.
E means Unsigned module has been loaded.
+ means that the module is being loaded.
- means that the module is being unloaded.
The source code for print_modules(), then module_flags(), and then print_tainted() functions may be helpful in figuring out the meaning of these and some other flags. Take a look at the comment just above print_tainted() function. Hope this helps.
Related
I'm trying to use the kernel's cpuset to isolate my process. To obtain this, I follow the instructions(2.1 Basic Usage) from kernel doc cpusets, however, it didn't work in my environment.
I have tried in both my centos7 server and my ubuntu16.04 work pc, but neither did work.
centos kernel version:
[root#node ~]# uname -r
3.10.0-327.el7.x86_64
ubuntu kernel version:
4.15.0-46-generic
What I have tried is as follows.
root#Latitude:/sys/fs/cgroup/cpuset# pwd
/sys/fs/cgroup/cpuset
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.cpus
0-3
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.mems
0
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.cpu_exclusive
1
root#Latitude:/sys/fs/cgroup/cpuset# cat cpuset.mem_exclusive
1
root#Latitude:/sys/fs/cgroup/cpuset# find . -name cpuset.cpu_excl
usive | xargs cat
0
0
0
0
0
1
root#Latitude:/sys/fs/cgroup/cpuset# mkdir my_cpuset
root#Latitude:/sys/fs/cgroup/cpuset# echo 1 > my_cpuset/cpuset.cpus
root#Latitude:/sys/fs/cgroup/cpuset# echo 0 > my_cpuset/cpuset.mems
root#Latitude:/sys/fs/cgroup/cpuset# echo 1 > my_cpuset/cpuset.cpu_exclusive
bash: echo: write error: Invalid argument
root#Latitude:/sys/fs/cgroup/cpuset#
It just printed the error bash: echo: write error: Invalid argument.
Google it, however, I can't get the correct answers.
As I pasted above, before my operation, I confirmed that the cpuset root path have enabled the cpu_exclusive function and all the cpus are not been excluded by other sub-cpuset.
By using ps -o pid,psr,comm -p $PID, I can confirm that the cpus can be assigned to some process if I don't care cpu_exclusive. But I have also proved that if cpu_exclusive is not set, the same cpus can also be assigned to another processes.
I don't know if it is because some pre-setting are missed.
What I expected is "using cpuset to obtain exclusive use of cpus". Can anyboy give any clues?
Thanks very much.
i believe it is a mis-understanding of cpu_exclusive flag, as i did. Here is the doc https://www.kernel.org/doc/Documentation/cgroup-v1/cpusets.txt, quoting:
If a cpuset is cpu or mem exclusive, no other cpuset, other than
a direct ancestor or descendant, may share any of the same CPUs or
Memory Nodes.
so one possible reason you have bash: echo: write error: Invalid argument, is that you have some other cgroup cpuset enabled, and it conflicts with your operations of echo 1 > my_cpuset/cpuset.cpu_exclusive
please run find . -name cpuset.cpus | xargs cat to list all your cgroup's target cpus.
assume you have 12 cpus, if you want to set cpu_exclusive of my_cpuset, you need to carefully modify all the other cgroups to use cpus, eg. 0-7, then set cpus of my_cpuset to be 8-11. After all these cpus configurations , you can set cpu_exclusive to be 1.
But still, other process can still use cpu 8-11. Only the tasks that belongs to the other cgroups will not use cpu 8-11
for me, i had some docker container running, which prevents me from setting my cpuset cpu_exclusive
with kernel doc, i do not think it is possible to use cpus exclusively by cgroup itself. One approach (i know this approach is running on production) is that we isolate cpus, and manage the cpu affinity/cpuset by ourselves
I am writing a bpf filter to prevent certain netlink messages. I am trying to debug the bpf code. Is there any debug tool that could help me?
I was initially thinking of using nlmon to capture netlink messages:
From https://jvns.ca/blog/2017/09/03/debugging-netlink-requests/
# create the network interface
sudo ip link add nlmon0 type nlmon
sudo ip link set dev nlmon0 up
sudo tcpdump -i nlmon0 -w netlink.pcap # capture your packets
Then use ./bpf_dbg (
https://github.com/cloudflare/bpftools/blob/master/linux_tools/bpf_dbg.c)
1) ./bpf_dbg to enter the shell (shell cmds denoted with '>'):
2) > load bpf 6,40 0 0 12,21 0 3 20... (this is the bpf code I intend to debug)
3) > load pcap netlink.pcap
4) > run /disassemble/dump/quit (self-explanatory)
5) > breakpoint 2 (sets bp at loaded BPF insns 2, do run then;
multiple bps can be set, of course, a call to breakpoint
w/o args shows currently loaded bps, breakpoint reset for
resetting all breakpoints)
6) > select 3 (run etc will start from the 3rd packet in the pcap)
7) > step [-, +] (performs single stepping through the BPF)
Did anyone try this before?
Also, I was not able to make nlmon module to load on my linux kernel(Is there a doc for this?)
I am running kernel version Linux version 4.10.0-40-generic
The nlmon module seems to be present in the kernel source:
https://elixir.free-electrons.com/linux/v4.10/source/drivers/net/nlmon.c#L41
But, when I search inside, /lib/modules/ for nlmon.ko I dont find anything.
instance-1:/lib/modules$ find . | grep -i nlmon
instance-1:/lib/modules$
I want to list all processes running on my Windows system using Ruby without installing any additional dependency or library that is not already part of Ruby. I have not found any way to do this online. Is there any clean way to do this from Ruby?
You can use the Kernal::system method to execute a command line argument. For example:
system("tasklist")
Image Name PID Session Name Session# Mem Usage
========================= ======== ================ =========== ============
System Idle Process 0 Services 0 24 K
...
ruby.exe 1336 Console 1 9,100 K
tasklist.exe 944 Console 1 5,332 K
Alternately--as points #Pavling out--you can use [Kernal::`](aka backtick), but some find it less readable. YMMV.
I fear that this is a very specific question.
Hardware: Gumstix Overo Fire (ARM Cortex A8)
Distro: Poky (customized with the Yocto Project)
Kernel: 3.5.7
I tried to write a program to read a HIH6130 i2c sensor, using /dev/i2c-3 and < linux/i2c-dev.h>, but despite it works for every other i2c device, it does not work for this one. Probably this happens because a particularity of the reading protocol, but anyway, that's not the topic.
I found this code that implements a driver for that sensor, and it is inside a so called "hwmon", which seems to be a collection of sensor drivers.
After successfully compiled and inserted this module I was expecting to see the entry humidity1_input somewhere under hwmon but I didn't find it.
root#overo:/sys# find -name hum*
root#overo:/sys# find -name hih*
./bus/i2c/drivers/hih6130
./module/hih6130
root#overo:/sys# ls ./bus/i2c/drivers/hih6130
bind module uevent unbind
root#overo:/sys# ls ./module/hih6130
coresize holders initstate refcnt srcversion uevent
drivers initsize notes sections taint
Do I have to do something else to enable the reading of this sensor? Any ideas?
I ended up using i2cget to read it:
$ i2cget -y 3 0x27 0x00
Later, the author, Iain Paton, kindly showed me how to bind the driver:
$ insmod hih6130.ko
$ echo hih6130 0x27 > /sys/bus/i2c/devices/i2c-3/new_device
In my device it appeared in this directory:
$ find /sys/ -name humidity*
/sys/devices/platform/omap_i2c.3/i2c-3/3-0027/humidity1_input
Also there is a 'temp1_input' in this same directory.
Does anyone know of a way to get U-boot version installed from userspace? There is the fw_printenv command that provides access to U-boot's environment variables, but not the version.
If U-boot is located in mtd0, you can get version info as follows:
root#SUPERWIFI:/proc# strings /dev/mtd0 | grep U-Boot
U-Boot 1.1.4-g1c8343c8-dirty (Feb 28 2014 - 13:56:54)
U-Boot
Now running in RAM - U-Boot at: %08lx
Just an update for this.
In our version of U-Boot we changed the code for main_loop() in main.c to this:
#ifdef CONFIG_VERSION_VARIABLE
char *oldver=getenv("ver");
if(oldver==0 ||strcmp(oldver,version_string))
{
setenv("ver", version_string); /* set version variable */
saveenv();
}
#endif /* CONFIG_VERSION_VARIABLE */
So setenv/saveenv is only called, if needed by an update.
In our firmware we added
/sbin/fw_printenv -n ver > /var/config/u-boot.ver
to make the u-boot version public available.
There's no defined way to do this. Once Linux boots, u-boot is no longer running and it's RAM is reclaimed for Linux's use. Linux doesn't even know about u-boot. Nor does it have to have been booted by u-boot.
If you really want to do this, the only way to do it is to add the u-boot version to the kernel's command line, write code to scan the u-boot image in flash for it's version, or something even nastier.
An alternative solution is to read the version directly from the u-boot binary file (can be even embedded in an image file containing other binaries as well like e.g. the first stage bootloader) with e.g. mmcblk0boot0 as partition (of device mmcblk0) the bootloader resides in:
sudo grep -a --null-data U-Boot /dev/mmcblk0boot0
Site note: Does work not only for Arch Linux but e.g. Ubuntu as well.
In my devices UBoot automatically creates a "ver" environment variable containing its version:
U-Boot > printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
bootdelay=3
bootcmd=bootm fc080000 - fc060000
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 08 2010 - 17:08:32)
Environment size: 253/131068 bytes
U-Boot >
I don't use fw_printenv, but I would imagine that this variable gets passed along as well. Maybe you already have something similar in your system?
UPDATE (5/23/2012):
I added fw_printenv to my linux image and can confirm that I do see the "ver" variable:
[root#ST600 /]# fw_printenv
baudrate=115200
ethact=FEC ETHERNET
ethaddr=24-db-ad-00-00-08
stdin=serial
stdout=serial
stderr=serial
ver=U-Boot 2009.03-svn9684 (Mar 11 2010 - 09:43:08)
bootcmd=bootm fc080000 - fc060000
bootdelay=3
bootargs=console=ttyCPM0,115200n8 rdinit=/sbin/init panic=10 mem=32m
[root#ST600 /]#
Try to read uboot version this way:
Find uboot partition, eg. for MTD device:
cat /proc/mtd
For /dev/mtd5:
cat /dev/mtd5 | hexdump -C -n 64
You can't rely on fw_printenv if you want to know u-boot version.
fw_printenv just looks for the printenv partition and dumps its data. So it's OK for normal variables, but it's not OK for the "ver" variable, which is dynamic, and whose value is initialized by u-boot when it boots. The value of this variable doesn't remain after u-boot exit, except if you manually save it to environment.
For example, on my board, if I print the "ver" variable from u-boot prompt:
U-Boot > printenv ver
ver=U-Boot 2009.11-00393-g5ca9497-dirty (Nov 26 2012 - 11:08:44)
This is the real version of u-boot, coming from u-boot itself.
Now, if I boot my board and use fw_printenv:
el#board # fw_printenv | grep ver=
ver=U-Boot 2009.11-00323-gbcc6e0e (Sep 21 2012 - 11:07:19)
As you can see, it's different. Because it happens that I have a "ver" variable defined in my environment. And it doesn't match the real u-boot version.
Of course, I could go back to u-boot, use "saveenv" to update the "ver" value in the environment. Then the two values would match. But then, I should always update the environment after changing u-boot.
So, my conclusion is that using fw_printenv to get u-boot version is definitely not a good idea.
If u-boot is residing in an MTD partition then this will work:
U_BOOT_VER=$(for part in `grep u-boot-[01] /proc/mtd | cut -f 1 -d ':'`; do strings /dev/${part} | grep "^U-Boot.*("; break; done)