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ratcheer
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PostPosted: Wed Mar 26, 2014 4:26 pm    Post subject: (Solved) New kernel is apparently not being used Reply with quote

I am pretty much a newbie with Gentoo. I need btrfs filesystem support. I followed the wiki article and rebuilt the kernel, adding btrfs as a built-in kernel object. When I boot the new kernel and try to manually mount a btrfs filesystem, I get "mount: unknown filesystem type 'btrfs'". I have double-checked the config, and btrfs is definitely selected with an "*", as the wiki instructs.

However, my question concerns the new kernel itself. There is only one kernel file in /boot, the one I created on Mar 25. However, if I run "uname -a", it reports that the kernel was built on Mar 20, which is probably the day I originally installed Gentoo. It seems that the original kernel is the one being used, even though it apparently no longer exists.

Here is the boot line from the grub2 configuration:

Code:
linux /boot/kernel-genkernel-x86_64-3.12.13-gentoo root=/dev/sdb13
initrd /boot/initramfs-genkernel-x86_64-3.12.13-gentoo


What am I missing? Thanks.

Tim


Last edited by ratcheer on Thu Mar 27, 2014 6:08 pm; edited 1 time in total
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NeddySeagoon
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PostPosted: Wed Mar 26, 2014 9:10 pm    Post subject: Reply with quote

ratcheer,

Welcome to Gentoo.

You probably have two locations on your system called /boot. They are not the same but can be difficult to tell apart.
The first one is your boot partition. grub is stored here along with your kernels. It will contain a directory called grub.

The second boot is the /boot directory on your root partition. This is normally empty until you mount the boot partition there.

By default, Gentoo does not mount boot at startup but it must be mounted when you install a new kernel.

Look in /boot with boot both mounted and unmounted.

I suspect you installed your new kernel to the wrong location.
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ratcheer
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PostPosted: Wed Mar 26, 2014 9:34 pm    Post subject: Reply with quote

Thanks for your reply. However, to the best of my knowledge, I do not have a boot partition. I am a Gentoo newbie, but not a Linux newbie. I will poke around and see if I can find some extra partition that I am unaware of.

Tim

Later - I have checked thoroughly. I do not see any additional partitions on my drives that I was unaware of. However, your premise does ring true - it must be finding that old kernel somewhere. I guess I need to look at every partition and see if I can find a gentoo kernel.

However, what about the fact that the grub command is specifically pointing at my Gentoo partition, /dev/sdb13 ?
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ratcheer
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PostPosted: Thu Mar 27, 2014 3:43 pm    Post subject: Reply with quote

Ok, after thinking about this overnight, I devised an experiment to determine whether grub is booting to a kernel in an unexpected location. I moved the new (Mar 25) kernel to another directory and rebooted. It failed because the kernel was not found. That shows me that the system is booting to the expected new kernel.

So, back to the original questions: 1) Why does the new kernel not support btrfs, which I config'ed into it? 2) Why does the new kernel still show an internal date of Mar 20, even though it was rebuilt on Mar 25 and the external file date is Mar 25?

Thanks for any assistance anyone can provide.

Tim
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Anon-E-moose
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PostPosted: Thu Mar 27, 2014 3:50 pm    Post subject: Reply with quote

post the whole grub.conf or at least a few lines before the one in your original post
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Anon-E-moose
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PostPosted: Thu Mar 27, 2014 3:53 pm    Post subject: Reply with quote

ratcheer wrote:
However, what about the fact that the grub command is specifically pointing at my Gentoo partition, /dev/sdb13 ?


All that does is tell grub/kernel that /dev/sdb13 is where ROOT will be, not where to boot from.
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ratcheer
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PostPosted: Thu Mar 27, 2014 4:53 pm    Post subject: Reply with quote

Ok, I am some kind of idiot, but I'm not yet sure what kind. :oops: The entire original question is not applicable. The new kernel is being used, but my config changes are not being taken in.

I am following the genkernel tutorial to the best of my ability, but my changes are not being incorporated. I am using options --menuconfig --no-mrproper --no-clean --install --symlink. I an saving the config at the end of the menuconfig phase. But, after everything is done, I browse the new config file in /etc/kernels, and BTRFS_FS is clearly not set. Why is my modified config not being used?

So, I still need help, but different help.

Tim
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Tractor Girl
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PostPosted: Thu Mar 27, 2014 5:12 pm    Post subject: Reply with quote

Code:
cd /usr/src/linux
make menuconfig

apply your stuff, save and quit
Code:
make && make modules_install
cp arch/x86_64/boot/bzImage /boot

(change arch if needed)
Code:
mv /boot/bzImage /boot/vmlinuz-3.13.2-whatever
genkernel --install initramfs

adjust grub2

Boot new kernel and check config
Code:
zgrep -i btrfs /proc/config.gz
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Anon-E-moose
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PostPosted: Thu Mar 27, 2014 5:12 pm    Post subject: Reply with quote

Are you rebuilding the kernel after configuring it?

No rebuild, no new kernel

Edit to add: It's as Tractor Girl says.
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ratcheer
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PostPosted: Thu Mar 27, 2014 5:27 pm    Post subject: Reply with quote

Ok, I'll try that, but none of the tutorials I'm trying to follow say anything like that. This is all very confusing.

Tim
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Tractor Girl
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PostPosted: Thu Mar 27, 2014 5:30 pm    Post subject: Reply with quote

Check here :wink:
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ratcheer
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PostPosted: Thu Mar 27, 2014 6:07 pm    Post subject: Reply with quote

Thanks very much Tractor Girl. Doing it manually worked, perfectly. I will follow those instructions (four posts up) from now on.

Tim
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