[Devel] RE: Containers HOWTO? (Where do I start?)

[Rob Landley]

> A few places to start since you want to start from the ground up:
>
> 1. man clone

Yup, got that one already.

> 2. man pivot_root

I wrote the busybox switch_root implementation, which meant I had to
really _understand_ the full horror of the pivot_root implementation
and why it _wasn't_ switch_root (examining every process in the system
so you can move their chroot entry for kernel threads and daemons is
really ugly, but you can't unmount a filesystem that has processes
pinning it).  Although come to think of it I thought kernel threads were
parked in initramfs these days?  (Doesn't initrd overmount initramfs?
Now I have to go look at what the code's doing again...)

But how does pivot_root enter into this when you haven't got an initrd to
free?  I thought when you killed a container's init process that killed all
the children and freed the resources, so how does pivot_root enter
into this?  (You don't reparent existing processes, you span new ones,
right?)

> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=tree;f=Documentation/cgroups;h=8c6b3f6c41a929f8db38b51a39442387ecbd5986;hb=HEAD

Ah, _that_ is what i was looking for.  Documentation/cgroups.

I'll look at #3 and #5 after reading that.

Thanks,

Rob
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