[gentoo-user] Safe way to test a new kernel?

[gentoo-user] Safe way to test a new kernel?

[Grant]

I need to test a kernel config change on a remote system.  Is there a
safe way to do this?  The fallback thing in grub has never worked for
me.  When does that ever work?

- Grant

[gentoo-user] Re: Safe way to test a new kernel?

[Nikos Chantziaras]

On 25/02/12 04:00, Grant wrote:
> I need to test a kernel config change on a remote system.  Is there a
> safe way to do this?  The fallback thing in grub has never worked for
> me.  When does that ever work?

You can press ESC in the Grub screen and it will take you to text-only 
mode.  There, you select an entry, press "e" and edit it.  Press ENTER 
when you're finished, and then press "b" to boot your modified entry.

That way, you can boot whatever kernel you want if the current one 
doesn't work.

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>> I need to test a kernel config change on a remote system.  Is there a
>> safe way to do this?  The fallback thing in grub has never worked for
>> me.  When does that ever work?
>
>
> You can press ESC in the Grub screen and it will take you to text-only mode.
>  There, you select an entry, press "e" and edit it.  Press ENTER when you're
> finished, and then press "b" to boot your modified entry.
>
> That way, you can boot whatever kernel you want if the current one doesn't
> work.

I can't do that remotely though.  I'm probably asking for something
that doesn't exist.

- Grant

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Michael Mol]

On Fri, Feb 24, 2012 at 9:08 PM, Grant <emailgrant@gmail.com> wrote:
>>> I need to test a kernel config change on a remote system.  Is there a
>>> safe way to do this?  The fallback thing in grub has never worked for
>>> me.  When does that ever work?
>>
>>
>> You can press ESC in the Grub screen and it will take you to text-only mode.
>>  There, you select an entry, press "e" and edit it.  Press ENTER when you're
>> finished, and then press "b" to boot your modified entry.
>>
>> That way, you can boot whatever kernel you want if the current one doesn't
>> work.
>
> I can't do that remotely though.  I'm probably asking for something
> that doesn't exist.

What's the nature of the remote box?

For example, I have a xen vps for which I can access the console via
ssh to the xen host machine. I can get at the grub menu that way. I
think grub supports serial consoles, but I don't know...


-- 
:wq

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Dale]

Grant wrote:
>>> I need to test a kernel config change on a remote system.  Is there a
>>> safe way to do this?  The fallback thing in grub has never worked for
>>> me.  When does that ever work?
>>
>>
>> You can press ESC in the Grub screen and it will take you to text-only mode.
>>  There, you select an entry, press "e" and edit it.  Press ENTER when you're
>> finished, and then press "b" to boot your modified entry.
>>
>> That way, you can boot whatever kernel you want if the current one doesn't
>> work.
> 
> I can't do that remotely though.  I'm probably asking for something
> that doesn't exist.
> 
> - Grant
> 
> 


There is a couple people on here that handle remote machines.  I'd be
shocked if there isn't a way to do this.  Just give them a bit to see
the thread.  I vaguely recall someone mentioning this but since my
remote machine is about 20 feet away, I didn't make notes.

Dale

:-)  :-)

-- 
I am only responsible for what I said ... Not for what you understood or
how you interpreted my words!

Miss the compile output?  Hint:
EMERGE_DEFAULT_OPTS="--quiet-build=n"

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Francisco Ares]

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On Sat, Feb 25, 2012 at 12:26 AM, Dale <rdalek1967@gmail.com> wrote:

> Grant wrote:
> >>> I need to test a kernel config change on a remote system.  Is there a
> >>> safe way to do this?  The fallback thing in grub has never worked for
> >>> me.  When does that ever work?
> >>
> >>
> >> You can press ESC in the Grub screen and it will take you to text-only
> mode.
> >>  There, you select an entry, press "e" and edit it.  Press ENTER when
> you're
> >> finished, and then press "b" to boot your modified entry.
> >>
> >> That way, you can boot whatever kernel you want if the current one
> doesn't
> >> work.
> >
> > I can't do that remotely though.  I'm probably asking for something
> > that doesn't exist.
> >
> > - Grant
> >
> >
>
>
> There is a couple people on here that handle remote machines.  I'd be
> shocked if there isn't a way to do this.  Just give them a bit to see
> the thread.  I vaguely recall someone mentioning this but since my
> remote machine is about 20 feet away, I didn't make notes.
>
> Dale
>
> :-)  :-)
>
> --
> I am only responsible for what I said ... Not for what you understood or
> how you interpreted my words!
>
> Miss the compile output?  Hint:
> EMERGE_DEFAULT_OPTS="--quiet-build=n"
>


That's right, there are many embedded machines out there with upgrades once
in a while.

Perhaps you would get better results asking at gentoo-embedded list.

Francisco

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Re: [gentoo-user] Re: Safe way to test a new kernel?

[Pandu Poluan]

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On Feb 25, 2012 9:14 AM, "Grant" <emailgrant@gmail.com> wrote:
>
> >> I need to test a kernel config change on a remote system.  Is there a
> >> safe way to do this?  The fallback thing in grub has never worked for
> >> me.  When does that ever work?
> >
> >
> > You can press ESC in the Grub screen and it will take you to text-only
mode.
> >  There, you select an entry, press "e" and edit it.  Press ENTER when
you're
> > finished, and then press "b" to boot your modified entry.
> >
> > That way, you can boot whatever kernel you want if the current one
doesn't
> > work.
>
> I can't do that remotely though.  I'm probably asking for something
> that doesn't exist.
>
> - Grant
>

Situations like these that made me decide with great conviction to always
deploy my servers virtualized, even if the box in question will only host a
single VM.

Now, if I lost my intelligence for a couple of seconds and somehow ended up
with a VM that's no longer accessible remotely, I just connect to the
virtual console.

The flip side? Now I'm getting too daring/careless, and the uptime now
drops below my (self-imposed) target of 99.99% :-P

Rgds,

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Re: [gentoo-user] Re: Safe way to test a new kernel?

[Mick]

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On Saturday 25 Feb 2012 02:32:49 Pandu Poluan wrote:
> On Feb 25, 2012 9:14 AM, "Grant" <emailgrant@gmail.com> wrote:
> > >> I need to test a kernel config change on a remote system.  Is there a
> > >> safe way to do this?  The fallback thing in grub has never worked for
> > >> me.  When does that ever work?
> > > 
> > > You can press ESC in the Grub screen and it will take you to text-only
> 
> mode.
> 
> > >  There, you select an entry, press "e" and edit it.  Press ENTER when
> 
> you're
> 
> > > finished, and then press "b" to boot your modified entry.
> > > 
> > > That way, you can boot whatever kernel you want if the current one
> 
> doesn't
> 
> > > work.
> > 
> > I can't do that remotely though.  I'm probably asking for something
> > that doesn't exist.
> > 
> > - Grant
> 
> Situations like these that made me decide with great conviction to always
> deploy my servers virtualized, even if the box in question will only host a
> single VM.
> 
> Now, if I lost my intelligence for a couple of seconds and somehow ended up
> with a VM that's no longer accessible remotely, I just connect to the
> virtual console.
> 
> The flip side? Now I'm getting too daring/careless, and the uptime now
> drops below my (self-imposed) target of 99.99% :-P

What do you do when you need to upgrade the host, rather than the guest?

-- 
Regards,
Mick

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Re: [gentoo-user] Re: Safe way to test a new kernel?

[Nilesh Govindrajan]

On Sat 25 Feb 2012 05:48:49 PM IST, Mick wrote:
> On Saturday 25 Feb 2012 02:32:49 Pandu Poluan wrote:
>> On Feb 25, 2012 9:14 AM, "Grant" <emailgrant@gmail.com> wrote:
>>>>> I need to test a kernel config change on a remote system.  Is there a
>>>>> safe way to do this?  The fallback thing in grub has never worked for
>>>>> me.  When does that ever work?
>>>>
>>>> You can press ESC in the Grub screen and it will take you to text-only
>>
>> mode.
>>
>>>>  There, you select an entry, press "e" and edit it.  Press ENTER when
>>
>> you're
>>
>>>> finished, and then press "b" to boot your modified entry.
>>>>
>>>> That way, you can boot whatever kernel you want if the current one
>>
>> doesn't
>>
>>>> work.
>>>
>>> I can't do that remotely though.  I'm probably asking for something
>>> that doesn't exist.
>>>
>>> - Grant
>>
>> Situations like these that made me decide with great conviction to always
>> deploy my servers virtualized, even if the box in question will only host a
>> single VM.
>>
>> Now, if I lost my intelligence for a couple of seconds and somehow ended up
>> with a VM that's no longer accessible remotely, I just connect to the
>> virtual console.
>>
>> The flip side? Now I'm getting too daring/careless, and the uptime now
>> drops below my (self-imposed) target of 99.99% :-P
>
> What do you do when you need to upgrade the host, rather than the guest?
>

I think setting up a VM on the server using the new kernel should help 
test a new kernel?

-- 
Nilesh Govindarajan
http://nileshgr.com

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>>>>>> I need to test a kernel config change on a remote system.  Is there a
>>>>>> safe way to do this?  The fallback thing in grub has never worked for
>>>>>> me.  When does that ever work?
>>>>>
>>>>> You can press ESC in the Grub screen and it will take you to text-only
>>>
>>> mode.
>>>
>>>>>  There, you select an entry, press "e" and edit it.  Press ENTER when
>>>
>>> you're
>>>
>>>>> finished, and then press "b" to boot your modified entry.
>>>>>
>>>>> That way, you can boot whatever kernel you want if the current one
>>>
>>> doesn't
>>>
>>>>> work.
>>>>
>>>> I can't do that remotely though.  I'm probably asking for something
>>>> that doesn't exist.
>>>>
>>>> - Grant
>>>
>>> Situations like these that made me decide with great conviction to always
>>> deploy my servers virtualized, even if the box in question will only host a
>>> single VM.
>>>
>>> Now, if I lost my intelligence for a couple of seconds and somehow ended up
>>> with a VM that's no longer accessible remotely, I just connect to the
>>> virtual console.
>>>
>>> The flip side? Now I'm getting too daring/careless, and the uptime now
>>> drops below my (self-imposed) target of 99.99% :-P
>>
>> What do you do when you need to upgrade the host, rather than the guest?
>>
>
> I think setting up a VM on the server using the new kernel should help
> test a new kernel?
>
> --
> Nilesh Govindarajan
> http://nileshgr.com

I haven't used a virtualized OS in awhile but the last time I did the
hardware interacting with the virtualized OS was also virtualized and
wasn't representative of the actual hardware.  I don't think I can
test the interaction between a kernel and my actual hardware from a
virtual OS.

- Grant

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Pandu Poluan]

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On Feb 25, 2012 7:22 PM, "Mick" <michaelkintzios@gmail.com> wrote:
>
> On Saturday 25 Feb 2012 02:32:49 Pandu Poluan wrote:
> > On Feb 25, 2012 9:14 AM, "Grant" <emailgrant@gmail.com> wrote:
> > > >> I need to test a kernel config change on a remote system.  Is
there a
> > > >> safe way to do this?  The fallback thing in grub has never worked
for
> > > >> me.  When does that ever work?
> > > >
> > > > You can press ESC in the Grub screen and it will take you to
text-only
> >
> > mode.
> >
> > > >  There, you select an entry, press "e" and edit it.  Press ENTER
when
> >
> > you're
> >
> > > > finished, and then press "b" to boot your modified entry.
> > > >
> > > > That way, you can boot whatever kernel you want if the current one
> >
> > doesn't
> >
> > > > work.
> > >
> > > I can't do that remotely though.  I'm probably asking for something
> > > that doesn't exist.
> > >
> > > - Grant
> >
> > Situations like these that made me decide with great conviction to
always
> > deploy my servers virtualized, even if the box in question will only
host a
> > single VM.
> >
> > Now, if I lost my intelligence for a couple of seconds and somehow
ended up
> > with a VM that's no longer accessible remotely, I just connect to the
> > virtual console.
> >
> > The flip side? Now I'm getting too daring/careless, and the uptime now
> > drops below my (self-imposed) target of 99.99% :-P
>
> What do you do when you need to upgrade the host, rather than the guest?
>

Since I'm using XenServer, upgrading the host is a well-defined procedure:
Either I push the update using XenCenter, or I visit the servers. Usually,
I just push minor updates using XenCenter.

Rgds,

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Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>> > >> I need to test a kernel config change on a remote system.  Is there a
>> > >> safe way to do this?  The fallback thing in grub has never worked for
>> > >> me.  When does that ever work?
>> > >
>> > > You can press ESC in the Grub screen and it will take you to text-only
>>
>> mode.
>>
>> > >  There, you select an entry, press "e" and edit it.  Press ENTER when
>>
>> you're
>>
>> > > finished, and then press "b" to boot your modified entry.
>> > >
>> > > That way, you can boot whatever kernel you want if the current one
>>
>> doesn't
>>
>> > > work.
>> >
>> > I can't do that remotely though.  I'm probably asking for something
>> > that doesn't exist.
>> >
>> > - Grant
>>
>> Situations like these that made me decide with great conviction to always
>> deploy my servers virtualized, even if the box in question will only host a
>> single VM.
>>
>> Now, if I lost my intelligence for a couple of seconds and somehow ended up
>> with a VM that's no longer accessible remotely, I just connect to the
>> virtual console.
>>
>> The flip side? Now I'm getting too daring/careless, and the uptime now
>> drops below my (self-imposed) target of 99.99% :-P
>
> What do you do when you need to upgrade the host, rather than the guest?
>
> --
> Regards,
> Mick

Exactly.

- Grant

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Robert David]

V Fri, 24 Feb 2012 18:08:43 -0800
Grant <emailgrant@gmail.com> napsáno:

> >> I need to test a kernel config change on a remote system.  Is
> >> there a safe way to do this?  The fallback thing in grub has never
> >> worked for me.  When does that ever work?
> >
> >
> > You can press ESC in the Grub screen and it will take you to
> > text-only mode. There, you select an entry, press "e" and edit it.
> >  Press ENTER when you're finished, and then press "b" to boot your
> > modified entry.
> >
> > That way, you can boot whatever kernel you want if the current one
> > doesn't work.
> 
> I can't do that remotely though.  I'm probably asking for something
> that doesn't exist.
> 
> - Grant
> 

Don't do that if you don't have some tool like KVM, or other remote
management of the server. Or if it is available in the data center,
just call them and order this service for the time you need to do
updates.

This is why I don't use gentoo on servers any more, just because
I rather stay safe than sorry.

But if you really need to do that (and you don't have any chance to
get KVM attached), just create an virtual machine with backup of your
server and test that kernel there, and check that you have all the
modules you need on the server. But this is the last thing I would do.


Good luck,
Robert.
 

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>> >> I need to test a kernel config change on a remote system.  Is
>> >> there a safe way to do this?  The fallback thing in grub has never
>> >> worked for me.  When does that ever work?
>> >
>> >
>> > You can press ESC in the Grub screen and it will take you to
>> > text-only mode. There, you select an entry, press "e" and edit it.
>> >  Press ENTER when you're finished, and then press "b" to boot your
>> > modified entry.
>> >
>> > That way, you can boot whatever kernel you want if the current one
>> > doesn't work.
>>
>> I can't do that remotely though.  I'm probably asking for something
>> that doesn't exist.
>>
>> - Grant
>>
>
> Don't do that if you don't have some tool like KVM, or other remote
> management of the server. Or if it is available in the data center,
> just call them and order this service for the time you need to do
> updates.
>
> This is why I don't use gentoo on servers any more, just because
> I rather stay safe than sorry.

How is another distro different in this situation?

- Grant


> But if you really need to do that (and you don't have any chance to
> get KVM attached), just create an virtual machine with backup of your
> server and test that kernel there, and check that you have all the
> modules you need on the server. But this is the last thing I would do.
>
>
> Good luck,
> Robert.

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Robert David]

V Sat, 25 Feb 2012 10:32:20 -0800
Grant <emailgrant@gmail.com> napsáno:

> >> >> I need to test a kernel config change on a remote system.  Is
> >> >> there a safe way to do this?  The fallback thing in grub has
> >> >> never worked for me.  When does that ever work?
> >> >
> >> >
> >> > You can press ESC in the Grub screen and it will take you to
> >> > text-only mode. There, you select an entry, press "e" and edit
> >> > it. Press ENTER when you're finished, and then press "b" to boot
> >> > your modified entry.
> >> >
> >> > That way, you can boot whatever kernel you want if the current
> >> > one doesn't work.
> >>
> >> I can't do that remotely though.  I'm probably asking for something
> >> that doesn't exist.
> >>
> >> - Grant
> >>
> >
> > Don't do that if you don't have some tool like KVM, or other remote
> > management of the server. Or if it is available in the data center,
> > just call them and order this service for the time you need to do
> > updates.
> >
> > This is why I don't use gentoo on servers any more, just because
> > I rather stay safe than sorry.
> 
> How is another distro different in this situation?
> 
> - Grant

Just because when using distros like Centos/RHEL or Debian stable, you
have very little chance that the kernel released will fail. Due to
extensive testing, user base and update policy. And major kernel update
you done only once in few years and the transition is tested before
release done (though you are supposed to test yourself to be safe).

This is not saying that gentoo is bad, I'm very big fan of gentoo.
But you have to concern where it use and where not. 

Robert.  


> 
> 
> > But if you really need to do that (and you don't have any chance to
> > get KVM attached), just create an virtual machine with backup of
> > your server and test that kernel there, and check that you have all
> > the modules you need on the server. But this is the last thing I
> > would do.
> >
> >
> > Good luck,
> > Robert.
> 

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>> >> >> I need to test a kernel config change on a remote system.  Is
>> >> >> there a safe way to do this?  The fallback thing in grub has
>> >> >> never worked for me.  When does that ever work?
>> >> >
>> >> >
>> >> > You can press ESC in the Grub screen and it will take you to
>> >> > text-only mode. There, you select an entry, press "e" and edit
>> >> > it. Press ENTER when you're finished, and then press "b" to boot
>> >> > your modified entry.
>> >> >
>> >> > That way, you can boot whatever kernel you want if the current
>> >> > one doesn't work.
>> >>
>> >> I can't do that remotely though.  I'm probably asking for something
>> >> that doesn't exist.
>> >>
>> >> - Grant
>> >>
>> >
>> > Don't do that if you don't have some tool like KVM, or other remote
>> > management of the server. Or if it is available in the data center,
>> > just call them and order this service for the time you need to do
>> > updates.
>> >
>> > This is why I don't use gentoo on servers any more, just because
>> > I rather stay safe than sorry.
>>
>> How is another distro different in this situation?
>>
>> - Grant
>
> Just because when using distros like Centos/RHEL or Debian stable, you
> have very little chance that the kernel released will fail. Due to
> extensive testing, user base and update policy. And major kernel update
> you done only once in few years and the transition is tested before
> release done (though you are supposed to test yourself to be safe).

Yuck. :)

> This is not saying that gentoo is bad, I'm very big fan of gentoo.
> But you have to concern where it use and where not.
>
> Robert.

Understood, thank you.

- Grant

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Pandu Poluan]

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On Feb 26, 2012 2:05 AM, "Robert David" <robert.david.public@gmail.com>
wrote:
>
> V Sat, 25 Feb 2012 10:32:20 -0800
> Grant <emailgrant@gmail.com> napsáno:
>
> > >> >> I need to test a kernel config change on a remote system.  Is
> > >> >> there a safe way to do this?  The fallback thing in grub has
> > >> >> never worked for me.  When does that ever work?
> > >> >
> > >> >
> > >> > You can press ESC in the Grub screen and it will take you to
> > >> > text-only mode. There, you select an entry, press "e" and edit
> > >> > it. Press ENTER when you're finished, and then press "b" to boot
> > >> > your modified entry.
> > >> >
> > >> > That way, you can boot whatever kernel you want if the current
> > >> > one doesn't work.
> > >>
> > >> I can't do that remotely though.  I'm probably asking for something
> > >> that doesn't exist.
> > >>
> > >> - Grant
> > >>
> > >
> > > Don't do that if you don't have some tool like KVM, or other remote
> > > management of the server. Or if it is available in the data center,
> > > just call them and order this service for the time you need to do
> > > updates.
> > >
> > > This is why I don't use gentoo on servers any more, just because
> > > I rather stay safe than sorry.
> >
> > How is another distro different in this situation?
> >
> > - Grant
>
> Just because when using distros like Centos/RHEL or Debian stable, you
> have very little chance that the kernel released will fail. Due to
> extensive testing, user base and update policy. And major kernel update
> you done only once in few years and the transition is tested before
> release done (though you are supposed to test yourself to be safe).
>
> This is not saying that gentoo is bad, I'm very big fan of gentoo.
> But you have to concern where it use and where not.
>
> Robert.
>

Anecdotal, but...

I once had an Ubuntu VM that can't shutdown after a kernel update. First
boot after update went well, but when I rebooted it again, it pegged its
vCPUs at 100% before I ordered the Xen hypervisor to put it out of its
misery.

The bug was apparently in the portion of the kernel running in the primary
CPU that's responsible for shutting down the other CPUs before cutting the
power. And IIRC, this bug affects all multi-processor configuration.

So, as you can see, binary distros can still fuck up royal time. Not to
mention that if you have an exotic configuration, support for your
configuration might not be built into the kernel by the distro.

Somehow I believe people deploying Gentoo servers will be much more
careful...

Rgds,

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Re: [gentoo-user] Re: Safe way to test a new kernel?

[Robert David]

V Sun, 26 Feb 2012 02:50:46 +0700
Pandu Poluan <pandu@poluan.info> napsáno:

> On Feb 26, 2012 2:05 AM, "Robert David"
> <robert.david.public@gmail.com> wrote:
> >
> > V Sat, 25 Feb 2012 10:32:20 -0800
> > Grant <emailgrant@gmail.com> napsáno:
> >
> > > >> >> I need to test a kernel config change on a remote system.
> > > >> >> Is there a safe way to do this?  The fallback thing in grub
> > > >> >> has never worked for me.  When does that ever work?
> > > >> >
> > > >> >
> > > >> > You can press ESC in the Grub screen and it will take you to
> > > >> > text-only mode. There, you select an entry, press "e" and
> > > >> > edit it. Press ENTER when you're finished, and then press
> > > >> > "b" to boot your modified entry.
> > > >> >
> > > >> > That way, you can boot whatever kernel you want if the
> > > >> > current one doesn't work.
> > > >>
> > > >> I can't do that remotely though.  I'm probably asking for
> > > >> something that doesn't exist.
> > > >>
> > > >> - Grant
> > > >>
> > > >
> > > > Don't do that if you don't have some tool like KVM, or other
> > > > remote management of the server. Or if it is available in the
> > > > data center, just call them and order this service for the time
> > > > you need to do updates.
> > > >
> > > > This is why I don't use gentoo on servers any more, just because
> > > > I rather stay safe than sorry.
> > >
> > > How is another distro different in this situation?
> > >
> > > - Grant
> >
> > Just because when using distros like Centos/RHEL or Debian stable,
> > you have very little chance that the kernel released will fail. Due
> > to extensive testing, user base and update policy. And major kernel
> > update you done only once in few years and the transition is tested
> > before release done (though you are supposed to test yourself to be
> > safe).
> >
> > This is not saying that gentoo is bad, I'm very big fan of gentoo.
> > But you have to concern where it use and where not.
> >
> > Robert.
> >
> 
> Anecdotal, but...
> 
> I once had an Ubuntu VM that can't shutdown after a kernel update.
> First boot after update went well, but when I rebooted it again, it
> pegged its vCPUs at 100% before I ordered the Xen hypervisor to put
> it out of its misery.

I don't want to start flame, but ubuntu was never a system for server
for me. It may be good for desktop, but not server. For me ubuntu is
too up-to-date to be a good server distro, even the LTS is not
something well done, maybe in version x.x.3-4 of LTS it s reasonable to
put on server, but it will soon end with support. So nothing for me.

> 
> The bug was apparently in the portion of the kernel running in the
> primary CPU that's responsible for shutting down the other CPUs
> before cutting the power. And IIRC, this bug affects all
> multi-processor configuration.
> 
> So, as you can see, binary distros can still fuck up royal time. Not
> to mention that if you have an exotic configuration, support for your
> configuration might not be built into the kernel by the distro.
> 

This is true, but you cannot compare countless options that gentoo can
be configured with few options that binary distro is capable and thus
more probably tested before.

> Somehow I believe people deploying Gentoo servers will be much more
> careful...

Agree. But real word is not so ideal. I got situations where I need
upgrade basic gentoo server to more special virtualized environment.
Just a customer wanted that. This consist about changing net to bridge,
add/update kernel modules, etc. I ended with bricked server after a
long checks etc, so I have to check the server physicaly. I did
another thing in debian remotely within a half hour.

This also implies that I'm not so good admin, but things happen not
so good as you expect every time.

I still use gentoo on my notebook and work computer, or specialized
project where it benefits. But all the servers are migrated to debian
or centos. I just don't have so much time to play.  

Robert.

> 
> Rgds,

 

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Alan McKinnon]

On Sun, 26 Feb 2012 02:50:46 +0700
Pandu Poluan <pandu@poluan.info> wrote:

> So, as you can see, binary distros can still fuck up royal time. Not
> to mention that if you have an exotic configuration, support for your
> configuration might not be built into the kernel by the distro.
> 
> Somehow I believe people deploying Gentoo servers will be much more
> careful...
> 

Oh, the people who deploy Gentoo are certainly that careful.

It's the junior admins who type "emerge world" and walk away that
aren't up to the task. I sadly had to ban Gentoo on production at work
for that reason, but it's still highly recommended for -dev and -stage
machines.

-- 
Alan McKinnnon
alan.mckinnon@gmail.com

[gentoo-user] Re: Safe way to test a new kernel?

[Nikos Chantziaras]

On 25/02/12 04:00, Grant wrote:
> I need to test a kernel config change on a remote system.  Is there a
> safe way to do this?  The fallback thing in grub has never worked for
> me.  When does that ever work?

Oh crap, you said "remote system".  Somehow I missed that.  Ignore my 
previous post since obviously accessing Grub on a remote machine would 
require a hardware VNC module (if you had that, then you wouldn't have 
posted about the issue in the first place, I assume.)

The way I dealt with it, is to use the "boot once" functionality of Grub:

http://weichong78.blogspot.com/2007/04/grub-test-kernel-once.html

I didn't bother with the panic handler, since I had remote hard-reset 
functionality (I recommend it; it can save your day.)

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Alan Mackenzie]

Hello, Nikos.

On Sat, Feb 25, 2012 at 04:10:10AM +0200, Nikos Chantziaras wrote:
> On 25/02/12 04:00, Grant wrote:
> > I need to test a kernel config change on a remote system.  Is there a
> > safe way to do this?  The fallback thing in grub has never worked for
> > me.  When does that ever work?

> Oh crap, you said "remote system".  Somehow I missed that.  Ignore my 
> previous post since obviously accessing Grub on a remote machine would 
> require a hardware VNC module (if you had that, then you wouldn't have 
> posted about the issue in the first place, I assume.)

> The way I dealt with it, is to use the "boot once" functionality of Grub:

> http://weichong78.blogspot.com/2007/04/grub-test-kernel-once.html

> I didn't bother with the panic handler, since I had remote hard-reset 
> functionality (I recommend it; it can save your day.)

What is this "remote hard-reset functionality", if you don't mind me
asking?  Do you mean somebody on the far end of a telephone line?

-- 
Alan Mackenzie (Nuremberg, Germany).

[gentoo-user] Re: Safe way to test a new kernel?

[Nikos Chantziaras]

On 25/02/12 16:04, Alan Mackenzie wrote:
> Hello, Nikos.
>
> On Sat, Feb 25, 2012 at 04:10:10AM +0200, Nikos Chantziaras wrote:
>> On 25/02/12 04:00, Grant wrote:
>>> I need to test a kernel config change on a remote system.  Is there a
>>> safe way to do this?  The fallback thing in grub has never worked for
>>> me.  When does that ever work?
>
>> Oh crap, you said "remote system".  Somehow I missed that.  Ignore my
>> previous post since obviously accessing Grub on a remote machine would
>> require a hardware VNC module (if you had that, then you wouldn't have
>> posted about the issue in the first place, I assume.)
>
>> The way I dealt with it, is to use the "boot once" functionality of Grub:
>
>> http://weichong78.blogspot.com/2007/04/grub-test-kernel-once.html
>
>> I didn't bother with the panic handler, since I had remote hard-reset
>> functionality (I recommend it; it can save your day.)
>
> What is this "remote hard-reset functionality", if you don't mind me
> asking?  Do you mean somebody on the far end of a telephone line?

No, it was a web interface button.  It was instant.  I assume it either 
cut the power to the slice or a controller was hooked up to the reset 
connector.

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>> I need to test a kernel config change on a remote system.  Is there a
>> safe way to do this?  The fallback thing in grub has never worked for
>> me.  When does that ever work?
>
>
> Oh crap, you said "remote system".  Somehow I missed that.  Ignore my
> previous post since obviously accessing Grub on a remote machine would
> require a hardware VNC module (if you had that, then you wouldn't have
> posted about the issue in the first place, I assume.)
>
> The way I dealt with it, is to use the "boot once" functionality of Grub:
>
> http://weichong78.blogspot.com/2007/04/grub-test-kernel-once.html

Perfect!  That's exactly what I need.  Here is an alternate method too:

http://fabbritech.blogspot.com/2009/07/make-grub-boot-something-once.html

I will test this ASAP.

- Grant

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>>> I need to test a kernel config change on a remote system.  Is there a
>>> safe way to do this?  The fallback thing in grub has never worked for
>>> me.  When does that ever work?
>>
>>
>> Oh crap, you said "remote system".  Somehow I missed that.  Ignore my
>> previous post since obviously accessing Grub on a remote machine would
>> require a hardware VNC module (if you had that, then you wouldn't have
>> posted about the issue in the first place, I assume.)
>>
>> The way I dealt with it, is to use the "boot once" functionality of Grub:
>>
>> http://weichong78.blogspot.com/2007/04/grub-test-kernel-once.html
>
> Perfect!  That's exactly what I need.  Here is an alternate method too:
>
> http://fabbritech.blogspot.com/2009/07/make-grub-boot-something-once.html
>
> I will test this ASAP.
>
> - Grant

I get "Unrecognized command" from savedefault in grub:

grub> savedefault --default=1 --once
Error 27: Unrecognized command

I re-emerged grub with /boot mounted and ran grub-install but I get
the same error.  Does anyone know how to fix this?  I'm on
grub-0.97-r10.

- Grant

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Alex Schuster]

Grant writes:

> I get "Unrecognized command" from savedefault in grub:
> 
> grub> savedefault --default=1 --once
> Error 27: Unrecognized command

Strange. Maybe this is something inofficial, and not every Gurb
understands this? The documentation does not mention the --default option
I think.

> I re-emerged grub with /boot mounted and ran grub-install but I get
> the same error.  Does anyone know how to fix this?  I'm on
> grub-0.97-r10.

Have a look at 'info grub', 'Booting' -> 'Making your system robust',
especially section 4.3.2 'Booting fallback systems'. That's what I used in
order to test new kernels remotely.

	Wonko

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Grant]

>> I get "Unrecognized command" from savedefault in grub:
>>
>> grub> savedefault --default=1 --once
>> Error 27: Unrecognized command
>
> Strange. Maybe this is something inofficial, and not every Gurb
> understands this? The documentation does not mention the --default option
> I think.
>
>> I re-emerged grub with /boot mounted and ran grub-install but I get
>> the same error.  Does anyone know how to fix this?  I'm on
>> grub-0.97-r10.
>
> Have a look at 'info grub', 'Booting' -> 'Making your system robust',
> especially section 4.3.2 'Booting fallback systems'. That's what I used in
> order to test new kernels remotely.
>
>        Wonko

I like that better.  Where do you execute 'grub-set-default 0'?

I did notice this:

"In some newer versions of GNU/Linux, there is no
/sbin/grub-set-default (eg. Debian 3.1, Fedora Core 4,5). While some
distributions like Gentoo still has /sbin/grub-set-default"

http://sidvind.com/wiki/GRUB:_Boot_another_OS_once#Method_1_.28preferred.29

BTW, is there a way to tell which grub entry I'm booted into, or am I
best off examining the contents of /proc/config.gz?

- Grant

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Alex Schuster]

Grant writes:

> > Have a look at 'info grub', 'Booting' -> 'Making your system robust',
> > especially section 4.3.2 'Booting fallback systems'. That's what I
> > used in order to test new kernels remotely.
> >
> >        Wonko
> 
> I like that better.  Where do you execute 'grub-set-default 0'?

I had it in /etc/init.d/local.start back when I used these features.
Nowadays with openrc I would put this line
in /etc/local.d/grub-default.start. I had some safety checks included,
like testing if networking and sshd was running, so this box would be
accessible from remote. But this is some years ago now, currently I do
not administrate such remote servers and so I have not used this
mechanism for a while.


> BTW, is there a way to tell which grub entry I'm booted into, or am I
> best off examining the contents of /proc/config.gz?

The first line in /boot/grub/default has the number of the default entry.
grub-set-default modifies this file, as does the GRUB savedefault command.

	Wonko

Re: [gentoo-user] Re: Safe way to test a new kernel?

[Nilesh Govindrajan]

On Sun 26 Feb 2012 08:05:23 PM IST, Grant wrote:
>>> I get "Unrecognized command" from savedefault in grub:
>>>
>>> grub> savedefault --default=1 --once
>>> Error 27: Unrecognized command
>>
>> Strange. Maybe this is something inofficial, and not every Gurb
>> understands this? The documentation does not mention the --default option
>> I think.
>>
>>> I re-emerged grub with /boot mounted and ran grub-install but I get
>>> the same error.  Does anyone know how to fix this?  I'm on
>>> grub-0.97-r10.
>>
>> Have a look at 'info grub', 'Booting' -> 'Making your system robust',
>> especially section 4.3.2 'Booting fallback systems'. That's what I used in
>> order to test new kernels remotely.
>>
>>        Wonko
>
> I like that better.  Where do you execute 'grub-set-default 0'?
>
> I did notice this:
>
> "In some newer versions of GNU/Linux, there is no
> /sbin/grub-set-default (eg. Debian 3.1, Fedora Core 4,5). While some
> distributions like Gentoo still has /sbin/grub-set-default"
>
> http://sidvind.com/wiki/GRUB:_Boot_another_OS_once#Method_1_.28preferred.29
>
> BTW, is there a way to tell which grub entry I'm booted into, or am I
> best off examining the contents of /proc/config.gz?
>
> - Grant
>

uname -r

If the kernel version is same, add a version string in menuconfig.

-- 
Nilesh Govindarajan
http://nileshgr.com

[gentoo-user] Re: Safe way to test a new kernel?

[Nikos Chantziaras]

(Hmm, GMane acting up again. Sorry if this shows up twice; I've sent 
this yesterday.)

On 25/02/12 04:00, Grant wrote:
> I need to test a kernel config change on a remote system.  Is there a
> safe way to do this?  The fallback thing in grub has never worked for
> me.  When does that ever work?

Oh crap, you said "remote system".  Somehow I missed that.  Ignore my 
previous post since obviously accessing Grub on a remote machine would 
require a hardware VNC module (if you had that, then you wouldn't have 
posted about the issue in the first place, I assume.)

The way I dealt with it, is to use the "boot once" functionality of Grub:

http://weichong78.blogspot.com/2007/04/grub-test-kernel-once.html

I didn't bother with the panic handler, since I had remote hard-reset 
functionality (I recommend it; it can save your day.)

[gentoo-user] Re: Safe way to test a new kernel?

[James]

Grant <emailgrant <at> gmail.com> writes:


> I need to test a kernel config change on a remote system.  Is there a
> safe way to do this?  The fallback thing in grub has never worked for
> me.  When does that ever work?

Grant,
If you have more than one system there, you can set the system to use
the serial port as a console. Then run a serial cable into the second 
system  and ssh into it to watch the boot process. Getting the keyboard
to work correctly via the ssh --> console-over-serial-port can be
tricky so it's best to set it up before you deploy remote hardware.

Also, I have used a cheap ebedded linux system when the second system
is not available.  Years ago, I even built a "reboot box"; it was
an embedded system with 4 relays and a 2 serial ports connected to different
system. I could physically remotely toggle the power. Several companies
build these devices, but, I have not used one in years.

Here is a google example I just found (never used this product)

http://www.youtube.com/watch?v=s9odA7LH91c

Just find a cheap embedded linux board with a 3-5 VAC(120). 


hth,
James