reboot

[Todd Millecam]

It depends on what you mean by "reboot."  If you mean going through
POST->BIOS->UEFI->Bootloader->kernel->PID 1->run level then it is possible
to update the kernel and system libraries without a full reboot.

You have to go through the kernel-> PID 1 (systemd or initd) -> and run
level again if you update your kernel, because everything after the kernel
relies on it and if you used resident binaries they'd make invalid system
calls and throw tons of exceptions.  If you update the kernel, you'll need
to clear out the memory of the old stuff and restart all your services and
running binaries with a kernel update.

The way you do it is through a program called kexec, usually found in the
kexec-tools package.

It works the same as grub command line options do--you pass in the new
kernel image and the initramfs as arguments using the -l switch to load it
into memory, and then use the -e switch to execute.  It'll keep you from
having to do all the hardware checks, and if you're using systemd on fairly
modern hardware (newer than 8 years) then it should only take about 3-10
seconds, which is usually in the category of imperceptible downtime for
end-users.



On Mon, Feb 9, 2015 at 4:47 AM, James Mcphee <jmcphe at gmail.com> wrote:

> Well, there is ksplice.  http://en.wikipedia.org/wiki/Ksplice  Oracle
> owns it.
>
> On Mon, Feb 9, 2015 at 1:15 AM, Michael Havens <bmike1 at gmail.com> wrote:
>
>> hmmmm.... bummer.
>>
>> :-)~MIKE~(-:
>>
>> On Mon, Feb 9, 2015 at 1:13 AM, James Mcphee <jmcphe at gmail.com> wrote:
>>
>>> You really don't.  There's been some work to dynamically reload, but I
>>> haven't seen anything terribly successful.
>>>
>>> On Mon, Feb 9, 2015 at 1:08 AM, Michael Havens <bmike1 at gmail.com> wrote:
>>>
>>>> How do you restart the kernel without rebooting? You know, to implement
>>>> a new version of the kernel?
>>>>
>>>> :-)~MIKE~(-:
>>>>
>>>> On Sun, Feb 8, 2015 at 8:16 PM, sean <sean.a.ritzler at gmail.com> wrote:
>>>>
>>>>> For libraries, you can restart any processes that have loaded the old
>>>>> libraries into memory. Generally you can use lsof to identify these
>>>>> processes.
>>>>>
>>>>> Rebooting will of course force all services to restart, thus making
>>>>> the updates "take effect". That's probably why he said that.
>>>>>
>>>>> On Sun, Feb 8, 2015 at 8:12 PM, Stephen Partington <
>>>>> cryptworks at gmail.com> wrote:
>>>>> > Depends on the update. Mainly kernel changes.
>>>>> >
>>>>> > On Feb 8, 2015 6:51 PM, "Michael Havens" <bmike1 at gmail.com> wrote:
>>>>> >>
>>>>> >> I got some guy saying you need to reboot Linux for updates to take
>>>>> effect.
>>>>> >> I tell him no then he changes his stance, you need to reboot for
>>>>> kernel and
>>>>> >> system library updates. I agree with the kernel upgrade but what
>>>>> about
>>>>> >> system libraries????
>>>>> >> :-)~MIKE~(-:
>>>>> >>
>>>>> >> ---------------------------------------------------
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>>>
>>>
>>>
>>> --
>>> James McPhee
>>> jmcphe at gmail.com
>>>
>>> ---------------------------------------------------
>>> PLUG-discuss mailing list - PLUG-discuss at lists.phxlinux.org
>>> To subscribe, unsubscribe, or to change your mail settings:
>>> http://lists.phxlinux.org/mailman/listinfo/plug-discuss
>>>
>>
>>
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>>
>
>
>
> --
> James McPhee
> jmcphe at gmail.com
>
> ---------------------------------------------------
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> http://lists.phxlinux.org/mailman/listinfo/plug-discuss
>



-- 
Todd Millecam
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