# kernel building problems (LXC)

## danboston

So I've been interested in LXC and had been reading up on it a bit, with intent to put it in on my Gentoo system.

I ran lxc-checkconfig and saw that there were several things I needed to add on my kernel.

At a stopping point: two of the items reported as "missing" by lxc-checkconfig are problems. The rest are now in the kernel.

One: If I put in CONFIG_IP6_NF_TARGET_MASQUERADE, the kernel will panic. 

Two: I cannot find "checkpoint restore" in order to put it in. the "/" search function of "make menuconfig" says it is here:

```

  | Symbol: CHECKPOINT_RESTORE [=n]

  | Type  : boolean

  | Prompt: Checkpoint/restore support

  |   Location:

  | (1) -> General setup

  |   Defined at init/Kconfig:1156

  |   Selects: PROC_CHILDREN [=n]

```

But it is not.

My main question is: will LXC be usable if the kernel does not have the above two items?

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## danboston

I was able to find "checkpoint restore".  Actually, it was more a matter of making it appear rather than finding it. Leaving out details, what I had to do was activate advanced options (or was it advanced features?) within the make menuconfig.

Adding the "checkpoint restore" option made the kernel panic.

So now I have two kernel items where adding either of them makes the kernel panic.

This is a problem.

This is good in a way, as now this thread is a solid discussion of kernel matters, no more mention of LXC.

My revised question is : how to add those two kernel items in a way that they do not cause kernel panics?

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## danboston

In the end, the problem was solved.

Booted into another linux. cat /proc/config.gz | gunzip, piped that to a file.  Booted into gentoo and ran "make oldconfig" on it.  Then tweaked to add the gentoo features back in.  Built, rebooted.  No panics, all desired items in.

Still don't know what the cause was.

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