On Sat, Sep 17, 2011 at 7:13 PM, Dale <[email protected]> wrote:
<SNIP>
>
> Ahhhhh. I see now. So, it mounts proc and sys but that is in the init then
> it mounts the real root outside the init. Then it umounts the proc and sys
> under the init and then switches to the real root and starts init there.
>
> Where does /usr and /var come in here? Isn't the init supposed to mount
> that too? Do I add that myself? If so, when to fsck get ran?
>
> Dale
Hi Dale,
Let's take a look at the script I sent you yesterday, copied here
again. This system uses a RAID6 for root. This RAID6 is built using
metadata type 1.2. (The newest at the time) Since the kernel only
assembles metadata type 0.9 automatically I had to use the initramfs
to do the assembly and mount.
c2stable / # cat /usr/src/initramfs/init
#!/bin/busybox sh
rescue_shell() {
echo "Something went wrong. Dropping you to a shell."
busybox --install -s
exec /bin/sh
}
# Mount the /proc and /sys filesystems.
mount -t proc none /proc
mount -t sysfs none /sys
# Do your stuff here.
echo "This script mounts rootfs and boots it up, nothing more!"
mdadm --assemble --name=c2stable:3 /dev/md3
# Mount the root filesystem.
mount -o ro /dev/md3 /mnt/root || rescue_shell
# Clean up.
umount /proc
umount /sys
# Boot the real thing.
exec switch_root /mnt/root /sbin/init
c2stable / #
There are really just 3 interesting parts to this:
1) The rescue_shell function
2) The assembly command
3) The mount command
When you read through the script you see I do the assembly and then
the mount. If the mount command fails then I drop into the rescue
shell which is a simple Linux environment where I can run mdadm by
hand to figure out what went wrong. If the mount succeeds then the
script just continues and Linux boots.
The only difference concerning your /usr question would be change the
mount command to something like:
mount -o ro /dev/sdaX /usr || rescue_shell
Does this make basic sense?
One point about static flag. Normally I don't build mdadm with static enabled:
c2stable ~ # emerge -pv mdadm
These are the packages that would be merged, in order:
Calculating dependencies... done!
[ebuild R ] sys-fs/mdadm-3.1.4 USE="-static" 282 kB
Total: 1 package (1 reinstall), Size of downloads: 282 kB
c2stable ~ #
but for the version I put in the initramfs I did enable it.
Cheers,
Mark
