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Dual Kernals - Concerning?

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Hello Community,

 

My system appears to be running tip top - I have been using fairly intensive programs (Ardour, Audacity and GIMP) without issue.  However, in the past few weeks when I have run

sudo apt-get update && sudo apt-get dist-upgrade

I have have noticed some oddities in the output...only during certain upgrades...

...
update-initramfs: Generating /boot/initrd.img-4.13.0-26-generic
update-initramfs: Generating /boot/initrd.img-4.4.0-36-generic

and...

...
Found background image: /etc/grub.d/backgrounds/grub.png
Found linux image: /boot/vmlinuz-4.13.0-26-generic
Found initrd image: /boot/initrd.img-4.13.0-26-generic
Found linux image: /boot/vmlinuz-4.4.0-36-generic
Found initrd image: /boot/initrd.img-4.4.0-36-generic
Found memtest86+ image: /boot/memtest86+.elf
Found memtest86+ image: /boot/memtest86+.bin
done

I am certain this is due to my kernel upgrade when the Spectre/Meltdown security issues went public.  I'm suspecting I have to "purge or remove" the old Kernal or something along those lines...

 

Or is this on the converse where it may be helpful to have this "backup" Kernal in case of an issue?  I haven't run different Kernals before so I don't have much experience.  Again, my system appears to be running just fine.

 

Thank you in advance, Community!

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Bodhi will never automatically add a new kernel to a users system. Changing kernels always risks breaking hardware support and we never want to do this.

 

That being said - having multiple kernel installs doesn't effect anything other than the disc space they take up. No harm in the slightest.

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There is no harm in having multiple kernels. You are only going to boot one at a time anyway ;)

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{bow head in shame}  I knew I was taking a risk with the kernal change...was just concerned about those threats.  I should have went with my gut that said things would be patched soon enough.  Also, from reading, these threats are real, but pretty obscure threats...it's not quite like SSL breaking.  I confess I was roped in with the hype.  Boo...

 

That said, thank you both kindly - your responses confirmed what I suspected as my machine seems to be purring along just fine.  I wasn't sure if it would cause issues up the road.

 

Thank you for alleviating my fears!

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There is a bonus to having access to more than one kernel. If a security patch or a software update cause issues with the kernel you are using, you may well be able to boot your system with the second kernel. This, however, is just my less than informed $0.02.

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There is a bonus to having access to more than one kernel. If a security patch or a software update cause issues with the kernel you are using, you may well be able to boot your system with the second kernel. This, however, is just my less than informed $0.02.

That is sort of what I thought I had heard at one point.  Would I just need to somehow point GRUB at it somehow?

 

***

 

Due to the patches/4.5.0, etc, should I revert to the Kernal Bodhi is on, or is it on 4.13.0-26 now?

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Bodhi will never automatically add a new kernel to a users system. Changing kernels always risks breaking hardware support and we never want to do this.

 

That being said - having multiple kernel installs doesn't effect anything other than the disc space they take up. No harm in the slightest.

 

True, but,

 

boot partition is only about 4 GB size in normal virtual (LVM) install, which could be eaten up fast after 4 to 5 kernel update.

 

This true for those using auto updated kernel repo like linux-signed-generic metapackage.

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That is sort of what I thought I had heard at one point.  Would I just need to somehow point GRUB at it somehow?

 

***

 

Due to the patches/4.5.0, etc, should I revert to the Kernal Bodhi is on, or is it on 4.13.0-26 now?

No, the 4.13.0-26 is not patched against meltdown or spectre.

As you already know, there are no issues with having more than one kernel, I always have two kernels in my systems. It could become a problem when you have to many and if you are booting in EFI mode, because your EFI partition might get full.

 

If you are afraid of meltdown or spectre and want to check if the kernel is patched do the following...

wget https://github.com/speed47/spectre-meltdown-checker/raw/master/spectre-meltdown-checker.sh
chmod +x ~/spectre-meltdown-checker.sh
sudo /home/$USER/spectre-meltdown-checker.sh

 Once you are done, if you don't want to keep this in your system for future use just open a terminal and run

rm spectre-meltdown-checker.sh

Make sure you are in the directory where you've placed the script in the first place. If you have followed the steps above, it will be in your home directory.

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True, but,

 

boot partition is only about 4 GB size in normal virtual (LVM) install, which could be eaten up fast after 4 to 5 kernel update.

 

This true for those using auto updated kernel repo like linux-signed-generic metapackage.

 

The metapackage contains a script that autoremoves the older kernels. AFAIK it keeps 3 or exceptionally 4 versions.

 

In /boot I have 3 versions available and the size per version is about 70 MB including vmlinuz, initrd and a few other files. I wonder what else you have in there to eat that 4 GB.

 

BTW, I use kernel 4.13.0-36-generic now and the script states that my system is not vulnerable (spectre 1,2 & meltdown) anymore. 

 

Enjoy,

Charles

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