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Questions tagged [kernel-parameters]

The tag has no usage guidance.

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0answers
9 views

will there be any bad effect after adding “acpi=noirq” to grub?

I'm using Arch + i3wm . When I try to suspend my laptop from any tty , I can resume without any problem. But while using GUI, if I suspend my laptop and try to resume I get stuck with do_IRQ: 0.55 No ...
0
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0answers
13 views

Kernel parameter about max threads not being applied

I have manually edited /etc/sysctl.conf and added this line kernel.threads-max=70000 However despite the fact that # cat /etc/sysctl.conf | grep thread kernel.threads-max=70000 what I see is that ...
0
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0answers
30 views

How to configure embedded linux kernel so that the file system is visible on the host linux

I am using a powerpc, and after building and flashing the linux kernel on the device I can see the file system. But if I try to create a user or make any changes they get erased and resets to default ...
2
votes
1answer
65 views

boot parameters seems not to work with ipxe and daily image

I am trying to auto install debian buster with ipxe, it seems that the boot parameters don't work in the ipxe menu. I always get the language section. So the preseed isn't loaded. Here is the relevant ...
0
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2answers
52 views

Setting Kernel parameters when grub.cfg is on another distro

My setup is: -Windows 10 on a M.2 SSD -Ubuntu 18.04 on a normal ssd (sdb) -Arch Linux on sdb as well but on different partitions I first installed ubuntu with grub and later added arch linux ...
0
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1answer
38 views

how to turn off tcp timestamps?

I tried to turn off the tcp timestamp but it didn't work. The step i performed are the following: $ sysctl -w net.ipv4.tcp_timestamps=0 $ sysctl -p $ sysctl net.ipv4.tcp_timestamps (=> to be sure ...
-1
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1answer
482 views

How to disable retpoline?

I need to disable retpoline for a use case. I tried adding noretpoline to the boot parameter but it doesn't seem to work. The output after adding noretpoline param: $ cat /sys/devices/system/cpu/...
1
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1answer
79 views

Can no_console_suspend be set in runtime?

Is it possible to change this value in runtime without rebooting? I don't always have this problem, when I suspend right now I'm getting a failure and Suspending console(s) (use no_console_suspend ...
4
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1answer
286 views

lsmod 'used by' shows -1 while CONFIG_MODULE_UNLOAD=y

In this post there is some explanation about why does lsmod show -2 in 'used by' column. The idea is that the kernel config option CONFIG_MODULE_UNLOAD was not set. But what if lsmod shows -1 only ...
0
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2answers
72 views

Is Linux kernel parameters separated by space (0x20) or NUL (0x0)?

I thought it was NUL. But today when I wrote a script, I found that it was space. Is it configurable? Or just my memory wrong?
1
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1answer
165 views

How to specify multiple schedulers on the kernel boot command line?

We have systems with both spinning mechanical disks, and NVME storage. We want to reduce the CPU overhead for IO by taking any IO scheduler out of the way. We want to specify this on the Linux boot ...
0
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1answer
107 views

How to add VM kernel parameters in Qubes OS 4.0 ?

How to add sysrq_always_enabled and audit=0 kernel parameters to an AppVM in QubesOS 4.0 ? Current /proc/cmdline inside the VM is: [user@dev01-w-s-f-fdr28 ~]$ cat /proc/cmdline root=/dev/mapper/...
1
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1answer
278 views

How to ensure SysRq is always enabled regardless of the kernel.sysrq setting?

Some Linux distributions have kernel.sysrq=16 which means only Sysrq+s (sync) is allowed. As an example: Fedora (25 and 28) has it set as such in /usr/lib/sysctl.d/50-default.conf I had to create a ...
0
votes
1answer
40 views

Understanding workload sharing of readwrite in fio

I am exploring fio tools with different options. I want to share the read and write workload, so supplied below jobfile to fio. [read-4K-write-64K] blocksize=4K,64K, rw=readwrite rwmixread=50 size=...
2
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1answer
351 views

Linux Modify/Add Kernel Command Line from InitramFS “UserSpace”

I am developing an embedded Linux device. I have successfully created an InitramFS CPIO archive that runs quickly after boot. Now, I want to change the initial kernel command line to include "quiet" ...
1
vote
1answer
384 views

How does FIO benchmark set IOdepth?

NOTE: My question stems from this other U&L Q - What exactly is iodepth in fio? I want to know how internally FIO sets I/O depth. I.e., one of the parameters we submit to FIO when we run it is "...
1
vote
1answer
111 views

Kernel flags for exact architecture [closed]

I am using linux-libre-4.17.3. I want to switch off all unnecescary stuff like 'Amateur radio', Xen, Hyper-V, Wifi drivers that I am not using and so on... I think web search does not satisfy me. ...
3
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1answer
389 views

Kernel parameters are not changed permanently for RHEL7

Trying to permanently change some vm kernel parameters, I created /etc/sysctl.d/01-custom.conf config file as it described in Red Hat knowledgebase article. Here is its content: # cat /etc/sysctl.d/...
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0answers
27 views

Weird kernel.shmax value [duplicate]

I've noticed that kernel.shmmax value is set to oddly huge number on my RHEL 7 system. # sysctl kernel.shmmax kernel.shmmax = 18446744073692774399 Is it OK to have such a huge number set? How can ...
0
votes
1answer
23 views

Boot kernel parameter to run an executable at the end of booting, if found

Is there such a feature? The executable would be run if found after the usual boot time mounting. Preferably standard Unix filesystem path; for example, /root/autorun.sh, not (hd0,0)/root/autorun.sh. ...
1
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0answers
232 views

Can't change kernel.printk value

I want to set kernel.printk value to 5 4 1 1 for disable logging on booting but when I try sysctl -w kernel.printk="5 4 1 1" I get error: sysctl: setting key "kernel.printk": Invalid argument ...
4
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1answer
495 views

Difference between modprobe and sysctl -w in terms of setting system parameters?

We know that sysctl command can change kernel parameters with : # sysctl -w kernel.domainname="example.com" or by directly editing the file in /proc/sys directory. And for persistent changes, the ...
1
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1answer
542 views

ACPI kernel parameter options for HP ProLiant DL380 G5

Heavily related to a question on the sister site (https://serverfault.com/questions/874943/debian-9-black-screen-during-install), I have recently picked up an HP ProLiant DL380 G5 and attempted to ...
1
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1answer
586 views

How to increase atomic DMA coherent pool?

I recently attempted to compile a device driver (Xilinx XAPP1052) on Fedora Workstation 20. It gave me the following error. ERROR: 256 KiB atomic DMA coherent pool is too small! Please ...
0
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1answer
340 views

Why does the fs.inode-max kernel tunable not exist on version 2.6 of the Linux kernel?

The following output (from a Vagrant VM running CentOS 6.6) mostly speaks for itself: [root@localhost ~]# echo 131072 > /proc/sys/fs/inode-max -bash: /proc/sys/fs/inode-max: No such file or ...
2
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1answer
402 views

What does the Linux kernel do with unknown kernel parameters?

Supposedly I passed the kernel a parameter that it doesn't understand, for example blabla or eat=cake, what would the kernel do with these unknown parameters, the traditional case would be passing any ...
0
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0answers
445 views

Compile Kernel 3.10.107 for Ubuntu 16.04 LTS

Is there a good way to compile and use kernel 3.10.107 on Ubuntu 16:04 LTS? My main reason is that I have development/server machine where I want to add additional USB device what have drivers only ...
1
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2answers
2k views

can't mount on /proc/cmdline

I followed the this instructions in order to change the kernel boot args after boot: https://wiki.archlinux.org/index.php/kernel_parameters#Hijacking_cmdline I created /root/cmdline , but when ...
2
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0answers
505 views

How to get video mode given by hwinfo when it doesn't work? And how to set login resolution?

I tried to follow the suggestion at this previous post: Use sudo hwinfo --framebuffer as described, choose a video mode you would like to see during boot in console, then add the option vga=nnn to ...
1
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1answer
805 views

Default kernel parameters on new network namespaces

What are the default kernel parameters, when creating a new network namespace? Is there a way to override them upon creation? I think they are inherited by the parent process. An example using ...
1
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1answer
3k views

Kernel module for net.bridge.bridge-nf-call-iptables

This is on the Linux OS. I see that on some machines the net.bridge.bridge-nf-call-iptables variable doesn't exist until I modprobe the br_netfilter filter. I also see that there are some machines ...
3
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1answer
1k views

LUKS password not being requested by dmcrypt / encrypt hook at boot

At boot I see: :: running hook [encrypt] A password is required to access the volume: Command requires device and mapped name as arguments Command requires device and mapped name as arguments ...
4
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1answer
1k views

LUKS discard/TRIM: conflicting kernel command line options

I'm confused between the various ways that LUKS/dmcrypt/cryptsetup discard /TRIM operations can be enabled via the Linux kernel command line. The dracut manpage: rd.luks.allow-discards Allow ...
4
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2answers
1k views

Select graphics card for console output

I have an HP DL380G9 server with two discreet nvidia graphics card installed running RHEL 6 with Kernel 2.6.32-573. Both cards have the same chipset (NV117) but different models. K620 (Slot 5 address ...
4
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1answer
6k views

Kernel 4.8.7 failure on cpufreq - CentOS 7

After upgrading my CentOS 7 kernel from 3.10.0 to 4.8.7, while rebooting the system I will get the following lines: [ 0.641455] cpufreq: cpufreq_online: Failed to initialize policy for cpu: 0 (-19)...
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0answers
3k views

Linux 3.x fails assigning PCI BAR memory

I got an IBM x3850 type 8864 machine, I can successfully boot using a 2.6.32 kernel but when I try to use a 3.10 kernel or newer the kernel fails to initialize all PCI slots (I can fix this (manually),...
8
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1answer
13k views

Cannot compile kernel: error, kernel does not support PIC mode

I have troubles recompiling my Kernel. Downloading the source package, decompress it and running fakeroot make-kpkg kernel_image leads me to the error [...] CHK include/...
3
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2answers
948 views

reboot with one-time kernel parameters

Is there a possibility to pass a (set of additional) kernel boot parameters to be applied at the next (re)boot, and only at that boot? I know that i could just interrupt grub and manually pass the ...
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0answers
201 views

Grub.conf vs sysctl.conf

Both files are being used to pass parameters to the kernel. so what exacly is the difference between the two? What is the purpose of each file?
0
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1answer
389 views

How can I configure the Linux kernel to ignore passed in parameters?

I have the kernel parameters for our embedded device set during kernel build time, but these can be overridden by passing other parameters from the bootloader. Is there a way to build a kernel that ...
1
vote
1answer
2k views

Kernel parameter quiet versus loglevel=4 and debug versus loglevel=7

Besides the possibility of userspace applications that care which one you use reading /proc/cmdline, what is the difference between using the kernel parameter quiet, versus loglevel=4, and the ...
5
votes
2answers
509 views

What are methods for recovering a Linux Kernel config?

I'm currently trying to rebuild the kernel for a proprietary device. In order to do this I will need to produce a kernel config for the device. While I could likely do this through trial and error, ...
1
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0answers
139 views

How to prevent access to HDD during Live-CD operation?

I want to safely disable the harddrive / harddisc (HDD) of my computer with boot parameters. I can not physically unplug it. BIOS / UEFI does not provide me an option to disable it. Can I use the ...
2
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1answer
5k views

Kernel parameters “console” and “earlycon” refer to old hardware?

I first found this by investigating parameters for earlycon but found that the options for console look almost identical. Both are present below and were taken from this source: From documentation ...
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1answer
789 views

How to configure device mapper name of encrypted root partition with Grub2?

I would like to have my encrypted root partition mapped to the device mapper name system, i.e. it should eventually appear under /dev/mapper/system. My operating system is Fedora 24 Workstation Linux ...
2
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1answer
1k views

How to let kernel not run the printk with KERN_DEBUG

I noticed that kernel has different console levels for the printk. I also noticed this post [1]. I understand that we can change the /proc/sys/kernel/printk to change the printk level for the ...
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0answers
173 views

How should the `crypto` kernel parameter be passed?

I've encrypted a root drive using a cipher with this format: <cipher>-<chainmode>-<ivmode>:<ivopt>. Let's call this [CIPHER] for short. To boot from this device, certain ...
0
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2answers
10k views

View current kernel parameters?

I saw in my syslog kernel.perf_event_max_sample_rate get changed. I was wondering if I could write a quick script to log this variable every few minutes. Currently it is: sysctl -a | grep kernel....
1
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1answer
1k views

Linux root on F2FS

I have my Linux root on an F2FS USB flash drive. The kernel is on another device accessible by the bootloader. I'm trying to start it with the parameters root=/dev/sda1 rootwait rootfstype=f2fs, but I ...
1
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1answer
261 views

Debian kernel runlevel parameter - xorg won't start with NVIDIA drivers

I am having trouble getting my display to work with the default debian kernel command line: \boot\vmlinuz-4.2.0-0.bpo.1-amd64 ro root=UUID=4e496eaa-bcf1-41a0-9eee-dd1c8367c855 initrd=boot\initrd.img-...