Questions tagged [kexec]

kexec is a system call that enables to load and boot into another kernel from the currently running kernel.

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Kexec: Can installer available in initramfs access (to copy) a file in disk storage

I am trying to migrate from one linux(embedded) say host to another say guest(without pendrive). kexec -l <installer> --initrd=< initramfs.cpio containing actual guest installer> I have ...
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1answer
48 views

SSH key added on boot without password prompt - how and why?

I have a passphrase-protected SSH key stored in ~/.ssh/id_rsa. In my .zshrc I have this fragment: if ! ssh-add -l > /dev/null; then ssh-add fi After booting, I usually open the terminal, see ...
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1answer
281 views

How to reset the video mode of the Intel driver i915 for the kexec-ed kernel so I can see what kexec kernel is doing?

I'm running Arch Linux and I've set up kdump so that when the current kernel panics(or I manually induce a crash via sysrq+c) then another kernel(the kexec kernel) starts up in order to create a crash ...
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2answers
276 views

Kexec into new kernel, but I can't access the initramfs prompt!

I used kexec to successfully load my kernel, but it's just printing dmesg lines. How do I get out of this to drop into the initramfs prompt? Ctrl-Alt-F2 just loads a black screen and ctrl-c does ...
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394 views

Hard lockup triggers reboot but no panic and no kdump

I have been trying to debug random system freezes when running the 4.14.93-rt kernel. To this end, I have enabled the lockup detector in the kernel using the following config: ...
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190 views

kexec: relocate_kernel fails

I am not able to get kexec to work. For x86_64 relocate_kernel fails to store information for jumping back. Kexec stops in movq %r9, CP_PA_TABLE_PAGE(%r11). works fine for kernel 4.4.162, doesn't ...
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1answer
2k views

How to umount /var /usr safely on systemd without reboot

I have a Linux server on a VM which the reboot does work as powering off due to misconfiguration of a third part provider. I do not have access to VM configuration. The person who installed the ...
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1answer
103 views

Could the capture kernel be used as a normal kernel after a kexec?

I have read about the kexec/kdump facilities, we know that crashed/panic'ed kernel is made available via /proc/vmcore. I have heard people use kexec based booting to bypass EFI/BIOS/FW initialization ...
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413 views

Kexec back to Grub2

I have an application where I need to boot to Linux with grub, execute automated scripts and then automatically boot to Windows. Can I use Kexec to run grub2 with a command line like: insmod ...
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39 views

Boot Linux from Linux on embedded board

I'd like to know, is there a way to boot a new Linux system, from a Linux ? Let me explain : I want to keep 2 systems separated on an embedded board. One system is used to perform tasks at the ...
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2answers
2k views

How to check if currently running Linux kernel has been loaded with kexec?

By checking I mean something quite rock-solid, i. e., trying to analyse loader's configuration or available kernel files and matching to uname's output clearly isn't an option.
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Reboot without having to decrypt LUKS partitions?

Is there a way to kexec reboot a running kernel without having to decrypt an encrypted LUKS root filesystem? I'd imagine not, but I'm not sure if there's a workaround for this.
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Boot rescue kernel at high memory address using kexec on arm

Summary: Crashkernel boots at 512MB address in RAM with kexec -e/-l but not with kexec -p - why? Embedded platform with Marvell Armada XP (MV78460) (ARMv7 with 4 cores) and 1GB of RAM. production ...
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1answer
709 views

kexec and USE_GRUB_CONFIG

I find kexec very useful to speed-up the reboot of Linux servers. One parameter into /etc/default/kexec is USE_GRUB_CONFIG. This parameter is meant to "read Grub configuration file". But I don't ...
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1answer
815 views

kexec crashing when booting a kernel without initramfs (ARM)

First, a few details about the setup: Linux-3.14.1 ARM am335x chip U-Boot bootloader What I am trying to achieve: U-Boot loads a kernel that contains an initramfs (call this kernel 1). U-Boot ...
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258 views

kexec doesn't unmount root filesystem

With a Debian Jessie 8.0, freshly installed (with systemd), I installed kexec. When I restart the computer with the reboot command, this invoke kexec. The reboot is ok but I have a message into the ...
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1answer
347 views

does the second kernel need kexec enabled

It's clear that you need the kexec syscalls in the 'first' kernel. But does the kernel that should get loaded (with kexec_load and reboot) need to be compiled with kexec? If yes, what extra code ...
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2answers
1k views

Easy way initrd to chain loading another kernel with kexec

I have here a machine which won't boot 64-bit kernels (it has efi32 with a little bit of... uncommon firmware). Currently, my only way to boot my 64-bit linux system is: Booting a 32-bit distro from ...