From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: ** X-Spam-Status: No, score=2.5 required=3.0 tests=BAYES_00,DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,HTML_MESSAGE,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 04350C433C1 for ; Tue, 23 Mar 2021 04:29:54 +0000 (UTC) Received: from shelob.surriel.com (shelob.surriel.com [96.67.55.147]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6BE9B6157F for ; Tue, 23 Mar 2021 04:29:53 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6BE9B6157F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernelnewbies-bounces@kernelnewbies.org Received: from localhost ([::1] helo=shelob.surriel.com) by shelob.surriel.com with esmtp (Exim 4.94) (envelope-from ) id 1lOYfV-00026Q-UI; Tue, 23 Mar 2021 00:29:25 -0400 Received: from mail-ej1-x62d.google.com ([2a00:1450:4864:20::62d]) by shelob.surriel.com with esmtps (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94) (envelope-from ) id 1lOYfU-00026L-1l for kernelnewbies@kernelnewbies.org; Tue, 23 Mar 2021 00:29:24 -0400 Received: by mail-ej1-x62d.google.com with SMTP id u9so24882416ejj.7 for ; Mon, 22 Mar 2021 21:29:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=LkMJmvAVBTji3qnQv0zwd968ovj3xYPgKrN2UxQ1fK4=; b=qXPeQZORcWA6M2peigPqXBqWg0bbpSOABBJtu//kmRj3h3mkAk/gC1MqgczxR6kpnh 3y5rRHeOGlzGIjWrk9h7bpFlRsYi1fF/6MKanSYSfFxQzLfxv4XNuxUa1CmotXF599uP lvaJ2fPjgUPuSSEM6ubRZDKX5Ii5aLds9PTzMWoPyd5KKAfpxWF51Utg/4gNYxrTuBRj vhBHiWXOkaAUfKwlsHVxRFvOqwa9zfHUf76t42kmd1BIBZx+lhUhSUm1vtCIASMkV+H7 KcBELE1deFedXz4BkpoRYb8E1vwd34m4qPnv/5F5IcSztFwCgCKi0Zc/iZA+pHmXDa2F MZeQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=LkMJmvAVBTji3qnQv0zwd968ovj3xYPgKrN2UxQ1fK4=; b=IzSQ8oXQ6/QS44yhpFB9KiI+TndbtWfKT2lEw26iWxVBb8kcrVtLl5EQJ4oBZobYmg zRYPKEDxjrBKr9hb3n7cMuWxIg395OadDbAkIrpwXNO/ORhOPq5V0SFm4HBIeNI9zQ3C dwyE8eVBUida/Jb9n31Ny6Skv1yXBEq+qVABZSTR8ayvGd+Q6kdGFJatMSV4Z7Iuz9Cz yjiZLsyYufH1q8eYbnGp2xldkVXZsiJawZltDOTzFuVxrRi99avpKNr9m0NtBmWi/k0r QIrkQZJn5Dz8hrJInyRpB6YFdCRuBpBiMbsuOfWXHZd3iWmYOLo2yJuAhCwkmlKkvxoC 1/Mg== X-Gm-Message-State: AOAM532Dl9olnaB93aNQ173vWMIkNksk/WMM674dmvJ8S2hk3w77IA55 3F5EvXvmiiwrhcSlpTHhNASqFCBAlLVUc9YgcWo= X-Google-Smtp-Source: ABdhPJw1o6Wfo61httBfwCXhyPwN2MegjuvxzFr7vw32tvHRH7N6TGzYnRDUKkTMxyIOiabIcAXQh+WNcKpIzlvKpis= X-Received: by 2002:a17:906:3295:: with SMTP id 21mr2977093ejw.88.1616473761957; Mon, 22 Mar 2021 21:29:21 -0700 (PDT) MIME-Version: 1.0 References: <87zgyvtkd8.fsf@miraculix.mork.no> <323555.1616462233@turing-police> In-Reply-To: <323555.1616462233@turing-police> From: Aruna Hewapathirane Date: Tue, 23 Mar 2021 00:29:10 -0400 Message-ID: Subject: Re: How to switch between installed kernel and developed kernel To: =?UTF-8?Q?Valdis_Kl=C4=93tnieks?= Cc: Gidi Gal , kernelnewbies X-BeenThere: kernelnewbies@kernelnewbies.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Learn about the Linux kernel List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: multipart/mixed; boundary="===============9001648069595205661==" Errors-To: kernelnewbies-bounces@kernelnewbies.org --===============9001648069595205661== Content-Type: multipart/alternative; boundary="0000000000005eca7305be2ca0d7" --0000000000005eca7305be2ca0d7 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, Mar 22, 2021 at 9:17 PM Valdis Kl=C4=93tnieks wrote: > On Tue, 23 Mar 2021 00:01:22 +0200, Gidi Gal said: > > > Many thanks for your reply, Aruna. Is there a way to remove the install= ed > > '5.12.0-rc3-GIDI_DEV+' kernel ? Yes there are 'many' ways to remove a kernel :-) A reverse command for the 'sudo make > > modules_install install' command ? I found this link which explains how > to > > do it manually ( > > https://www.cyberciti.biz/faq/debian-redhat-linux-delete-kernel-command= / > ), > > I wonder if there is a safer way. > Type linux into your shell then press the 'tab' key twice.. you will see a list of commands. Use : linux-check-removal Once you are comfortable with compiling + linking/building +running a custom kernel what is preventing you from writing 'your own command' to do exactly that ? Say a bash script ? Or Python program ? > I can't speak for Debian, but I've used both the RedHat rpm method and ju= st > using the 'rm' command for self-bullt kernels since the 2.5.47 kernel or = so > (Egads, that was November 2002). As long as you follow the directions, y= ou > should be OK. 'rm' can get dangerous if you get over-exuberant with usin= g > '*' > characters, but you already knew that, right? :) > If you have to use rm always use it with the -i flag. Always prompt before removal. > And if you followed my recommendation and back up /boot, you'll be all > set to restore whatever you mess up. Listen to Valdis in this case and follow orders religioulsy. Back up not just /boot but anything and everything that is important for you. > The running kernel will work just fine > as long as you don't reboot. And unless you did 'rm /boot/*', you should > have > at least one usable kernel left... > > Seriously - if you're not comfortable with that level of sysadmin > procedures, > maybe you shouldn't be a kernel hacker... Do not listen to Valdis in this case as we were all newbies at one time like Dan Carpenter told me which I will remember to my dying day. Do not let anyone tell you what you can or cannot do when it come's to the kernel because believe me like me you will find out over time the kernel is a living thing that has very subtle ways of informing you when you did something and it is not happy :-) So compile away to your hearts content and go ahead and break things like I did that is actually a very good way to learn. And listen to more experienced folk like Valdis who probably knows more about all the subsystems than anyone. But if anyone tells you you should not be a kernel hacker then prove them wrong ? Actually that is Valdis's way of motivating you. So good luck and we are here if you have questions :-) there is always the possibility of > something you didn't know about trashing your system. See > 5.12.0-rc1-dontuse > for a nasty bug with file-backed swap that would stomp all over a section > of your > filesystem, and there was an ext[34] (can't remember anymore) bug during > 2.5 > that would trash the filesystem when you *unmounted* it. So you could > boot the > new kernel for testing, shutdown and boot the older version, and find it > won't boot and be blaming the older version until we figured out what was > happening. :) > > But seriously - if you have a good backup of the system, and an bootable > external image that you can use for rescue, there's not much a kernel > screw-up > can do to permanently lose date. > Agreed 110%. > > Of course, WIndows Update is at that same level of reliability, so > "knowing how > to recover a trashed system" is an important skill no matter what OS you > run :) > Hope this helps - Aruna --0000000000005eca7305be2ca0d7 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable
On Mon, Mar 22, 2021 at 9:17 PM Valdis Kl=C4=93tnieks <valdis.kletnieks@vt.edu> wrote:
=
On Tue, 23 Mar 2021= 00:01:22 +0200, Gidi Gal said:

> Many thanks for your reply, Aruna. Is there a way to remove the instal= led
> '5.12.0-rc3-GIDI_DEV+' kernel ?

Yes there are 'many' ways to remove a kernel :-)

=
A reverse command f= or the 'sudo make
> modules_install install' command ? I found this link which explain= s how to
> do it manually (
> https://www.cyberciti.b= iz/faq/debian-redhat-linux-delete-kernel-command/),
> I wonder if there is a safer way.

= Type linux into your shell then press the 'tab' key twice.. you wil= l see a list of commands.

Use : linux-check-re= moval <uname-r of your kernel to remove>
Once you are comfortable with compiling + linking/building +run= ning a custom kernel
what is preventing you from writing 'you= r own command' to do exactly that ? Say a bash
script ? Or Py= thon program ?=C2=A0
=C2=A0
I can't speak for Debian, but I've used both the RedHat rpm method = and just
using the 'rm' command for self-bullt kernels since the 2.5.47 kern= el or so
(Egads, that was November 2002).=C2=A0 As long as you follow the directions= , you
should be OK.=C2=A0 'rm' can get dangerous if you get over-exuberan= t with using '*'
characters, but you already knew that, right? :)

<= /div>
If you have to use rm always use it with the -i flag. Always prom= pt before removal.
=C2=A0
And if you followed my recommendation and back up /boot, you'll be all<= br> set to restore whatever you mess up.=C2=A0

Listen to Valdis in this case and follow orders religioulsy. Back up not j= ust /boot but anything
and everything that is important for you.
=C2=A0
The = running kernel will work just fine
as long as you don't reboot. And unless you did 'rm /boot/*', y= ou should have
at least one usable kernel left...

Seriously - if you're not comfortable with that level of sysadmin proce= dures,
maybe you shouldn't be a kernel hacker...

<= div>Do not listen to Valdis in this case as we were all newbies at one time= like Dan Carpenter told me
which I will remember to my dying day= . Do not let anyone tell you what you can or cannot do when it
co= me's to the kernel because believe me like me you will find out over ti= me the kernel is a living thing that
has very subtle ways of info= rming you when you did something and it is not happy :-)

So compile= away to your hearts content and go ahead and break things like I did that = is actually a very good way to learn.
And listen to more exp= erienced folk like Valdis who probably knows more about all the subsystems = than anyone. But if anyone tells you
you should not be a ker= nel hacker then prove them wrong ? Actually that is Valdis's way of mot= ivating you.

So good luck and we are here if you h= ave questions :-)

there is always the possibility of
something you didn't know about trashing your system.=C2=A0 See 5.12.0-= rc1-dontuse
for a nasty bug with file-backed swap that would stomp all over a section o= f your
filesystem, and there was an ext[34] (can't remember anymore) bug durin= g 2.5
that would trash the filesystem when you *unmounted* it.=C2=A0 So you could= boot the
new kernel for testing, shutdown and boot the older version, and find it won't boot and be blaming the older version until we figured out what w= as
happening. :)

But seriously - if you have a good backup of the system, and an bootable external image that you can use for rescue, there's not much a kernel s= crew-up
can do to permanently lose date.

Agreed= 110%.

Of course, WIndows Update is at that same level of reliability, so "kn= owing how
to recover a trashed system" is an important skill no matter what OS y= ou run :)

=C2=A0Hope this helps - Arun= a
--0000000000005eca7305be2ca0d7-- --===============9001648069595205661== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies --===============9001648069595205661==--