PID of init != 1 when initrd with pivot_root
Well, I upgraded and found pivot_root and the problem is that how do I make init run with PID 1. My linuxrc gets PID 7.
1 ? 00:03:05 swapper
2 ? 00:00:00 keventd
3 ? 00:00:00 kswapd
4 ? 00:00:00 kreclaimd
5 ? 00:00:00 bdflush
6 ? 00:00:00 kupdated
7 ? 00:00:00 linuxrcinit doesn't like running with any other PID than 1. I could probably revert to the not so old way of doing things and exit linuxrc and let the kernel change root. But then I wouldn't be able to mount root over samba :-(. ( not that I have any samba shares :-)
Ivan Vadovic
Followup to: <[email protected]> By author: Ivan <[email protected]> In newsgroup: linux.dev.kernel
Quoted 12 lines
Well, I upgraded and found
pivot_rootand the problem is that how do I make init run with PID 1. My linuxrc gets PID 7.1 ? 00:03:05 swapper 2 ? 00:00:00 keventd 3 ? 00:00:00 kswapd 4 ? 00:00:00 kreclaimd 5 ? 00:00:00 bdflush 6 ? 00:00:00 kupdated 7 ? 00:00:00 linuxrc
Quoted 5 lines
init doesn't like running with any other PID than 1. I could probably revert to the not so old way of doing things and exit linuxrc and let the kernel change root. But then I wouldn't be able to mount root over samba :-(. ( not that I have any samba shares :-)
This is this way for backwards bug compatibility. Use the following command line options to make it behave properly:
ram=/dev/ram0 init=/linuxrc
-hpa
Signature · 3 lines
<[email protected]> at work, <[email protected]> in private! "Unix gives you enough rope to shoot yourself in the foot." http://www.zytor.com/~hpa/puzzle.txt
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Well, I upgraded and found
pivot_rootand the problem is that how do I make init run with PID 1. My linuxrc gets PID 7.1 ? 00:03:05 swapper 2 ? 00:00:00 keventd 3 ? 00:00:00 kswapd 4 ? 00:00:00 kreclaimd 5 ? 00:00:00 bdflush 6 ? 00:00:00 kupdated 7 ? 00:00:00 linuxrcQuoted 4 lines
init doesn't like running with any other PID than 1. I could probably revert to the not so old way of doing things and exit linuxrc and let the kernel change root. But then I wouldn't be able to mount root over samba :-(. ( not that I have any samba shares :-)
Quoted 4 lines
This is this way for backwards bug compatibility. Use the following command line options to make it behave properly:
ram=/dev/ram0 init=/linuxrc
That's what I did, almost. I think you meant root=/dev/rd/0 init=/linuxrc ( with devfs) though init parameter is made redundant by the new "root change mechanism" pivot_root.
But the problem still remains. How do I make my /sbin/init run with PID 1 using initial ramdisk under the new root change mechanism? I don't want to use the old change_root mechanism since the Documentation/initrd.txt says:
Obsolete root change mechanism
------------------------------
The following mechanism was used before the introduction of pivot_root. Current kernels still support it, but you should _not_ rely on its continued availability.
...
This old, deprecated mechanism is commonly called "change_root", while the new, supported mechanism is called "pivot_root".
--
Ivan Vadovic
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Well, I upgraded and found
pivot_rootand the problem is that how do I make init run with PID 1. My linuxrc gets PID 7.1 ? 00:03:05 swapper ... 7 ? 00:00:00 linuxrcQuoted 5 lines
init doesn't like running with any other PID than 1. I could probably revert to the not so old way of doing things and exit linuxrc and let the kernel change root. But then I wouldn't be able to mount root over samba :-(.
...
This is this way for backwards bug compatibility. Use the following command line options to make it behave properly:
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ram=/dev/ram0 init=/linuxrc
...
But the problem still remains. How do I make my
/sbin/initrun with PID 1 using initial ramdisk under the new root change mechanism? I don't want to use the oldchange_rootmechanism...
I had the same problem when doing some development for mkCDrec. This project uses busybox, whose init does not run if its PID != 1. I asked the busybox folks same question you did and never got a response.
As a kludge, and after looking at the busybox source code, I renamed init to linuxrc. In this case the program is functionally equivalent to init, except that it does not do the PID == 1 check.
An excerpt from my real linuxrc:
echo Pivot_root: my PID is $$
# exec /usr/sbin/chroot . /sbin/init < dev/console > dev/console 2>&1 # Okay, try this: exec /usr/sbin/chroot . /sbin/linuxrc < /dev/console > /dev/console 2>&1
/sbin/linuxrc is actually init, renamed.
I am sure this is not the preferred method. Please let me know if you find the correct solution.
Signature · 3 lines
W. Michael Petullo :wq
Quoted 7 lines · W. Michael Petullo
Quoted 3 lines
But the problem still remains. How do I make my
/sbin/initrun with PID 1 using initial ramdisk under the new root change mechanism? I don't want to use the oldchange_rootmechanism...I had the same problem when doing some development for mkCDrec. This project uses busybox, whose init does not run if its PID != 1. I asked the busybox folks same question you did and never got a response.
Maybe I'm wrong here, but I had the same problem at some point and my solution was to rename /linuxrc (to /linux, and booting with init=/linux). I believe the code which special cases /linuxrc might be in the way here.
Maybe you want to try this, if it helps I think Documentation/initrd.txt needs to be updated.
--Kai
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But the problem still remains. How do I make my
/sbin/initrun with PID 1 using initial ramdisk under the new root change mechanism? I don't want to use the oldchange_rootmechanism...I had the same problem when doing some development for mkCDrec. This project uses busybox, whose init does not run if its PID != 1. I asked the busybox folks same question you did and never got a response.
As a kludge, and after looking at the busybox source code, I renamed init to linuxrc. In this case the program is functionally equivalent to init, except that it does not do the PID == 1 check.
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An excerpt from my real linuxrc:
echo
Pivot_root: my PID is $$# exec /usr/sbin/chroot . /sbin/init < dev/console > dev/console 2>&1 # Okay, try this: exec /usr/sbin/chroot . /sbin/linuxrc < /dev/console > /dev/console 2>&1
/sbin/linuxrcis actually init, renamed.
I fugured it out. The Documentation/initrd.txt says to use root=/dev/rd/0 with devfs. Well, that's wrong. You should use root=/dev/ram0 even with devfs no matter what the documentation says. And my linuxrc finaly runs with PID == 1.
Ivan Vadovic