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From: Lawrence D'Oliveiro <ldo@nz.invalid>
Newsgroups: comp.os.linux.advocacy,alt.comp.os.windows-11
Subject: Re: Kexec (and HyperV) (was: Re: Dimdows Decay Syndrome Continues)
Date: Sat, 8 Feb 2025 23:42:11 -0000 (UTC)
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On 8 Feb 2025 08:44:20 GMT, vallor wrote:

> On Sat, 8 Feb 2025 06:36:16 -0000 (UTC), Lawrence D'Oliveiro
> <ldo@nz.invalid> wrote in <vo6u10$3ue2q$1@dont-email.me>:
> 
>> Doesn’t RHEL support kexec, which
>> allows the old Linux kernel to pass control to the new one without
>> actually disrupting the userland?
> 
> You're thinking of live kernel patching.  kexec_load(2) load a kernel
> that you can have execute if the current kernel crashes.  You do this
> for debugging, usually.

Bit more than that <https://manpages.debian.org/kexec_load(2)>:

    The kexec_load() system call loads a new kernel that can be
    executed later by reboot(2).

And one of the functions of the latter
<https://manpages.debian.org/reboot(2)> is:

    LINUX_REBOOT_CMD_KEXEC
      (RB_KEXEC, 0x45584543, since Linux 2.6.13). Execute a kernel
      that has been loaded earlier with kexec_load(2).