* Re: initrd help -- umounts root after pivot_root
@ 2003-10-31 12:46 Bob Chiodini
2003-10-31 18:13 ` Maciej Zenczykowski
2003-10-31 21:59 ` H. Peter Anvin
0 siblings, 2 replies; 6+ messages in thread
From: Bob Chiodini @ 2003-10-31 12:46 UTC (permalink / raw)
To: linux-kernel
On Thu, 2003-10-30 at 19:18, John R Moser wrote:
> Been trying with 2.4.20, 2.4.22, 2.6.0-test9, how the heck do I get this
> to work?
>
> I set everthing up on /dev/shm type tmpfs, then
> cd /dev/shm
> mkdir initrd
> pivot_root . initrd
John,
It does not appear that the kernel(s) will support the root fs on
tmpfs. Looking through the init kernel code: It boils down to a block
device with real major and minor number or NFS.
Could you set up a ramdisk to do the same thing as /dev/shm? Also,
you'll have to tell the kernel where root is, either a boot parameter
(root=xxx) or with the rdev command.
Bob...
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: initrd help -- umounts root after pivot_root
2003-10-31 12:46 initrd help -- umounts root after pivot_root Bob Chiodini
@ 2003-10-31 18:13 ` Maciej Zenczykowski
2003-10-31 21:59 ` H. Peter Anvin
1 sibling, 0 replies; 6+ messages in thread
From: Maciej Zenczykowski @ 2003-10-31 18:13 UTC (permalink / raw)
To: Bob Chiodini; +Cc: linux-kernel
Have you remember to perform
echo 0x0100 > /proc/sys/kernel/real-root-dev
in the /linuxrc init script?
Cheers,
MaZe.
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: initrd help -- umounts root after pivot_root
2003-10-31 12:46 initrd help -- umounts root after pivot_root Bob Chiodini
2003-10-31 18:13 ` Maciej Zenczykowski
@ 2003-10-31 21:59 ` H. Peter Anvin
2003-11-03 13:47 ` Bob Chiodini
1 sibling, 1 reply; 6+ messages in thread
From: H. Peter Anvin @ 2003-10-31 21:59 UTC (permalink / raw)
To: linux-kernel
From: H. Peter Anvin <hpa@zytor.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 8bit
X-Comment-To: Bob Chiodini <robert.chiodini-1@ksc.nasa.gov>
Disclaimer: Not speaking for Transmeta in any way, shape, or form.
Copyright: Copyright 2003 H. Peter Anvin - All Rights Reserved
Followup to: <1067604362.5526.15.camel@tweedy.ksc.nasa.gov>
By author: Bob Chiodini <robert.chiodini-1@ksc.nasa.gov>
In newsgroup: linux.dev.kernel
>
> John,
>
> It does not appear that the kernel(s) will support the root fs on
> tmpfs. Looking through the init kernel code: It boils down to a block
> device with real major and minor number or NFS.
>
Baloney. See the SuperRescue CD, for example, for a distro which uses
exactly this.
-hpa
--
<hpa@transmeta.com> at work, <hpa@zytor.com> in private!
If you send me mail in HTML format I will assume it's spam.
"Unix gives you enough rope to shoot yourself in the foot."
Architectures needed: ia64 m68k mips64 ppc ppc64 s390 s390x sh v850 x86-64
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: initrd help -- umounts root after pivot_root
2003-10-31 21:59 ` H. Peter Anvin
@ 2003-11-03 13:47 ` Bob Chiodini
0 siblings, 0 replies; 6+ messages in thread
From: Bob Chiodini @ 2003-11-03 13:47 UTC (permalink / raw)
To: H. Peter Anvin; +Cc: linux-kernel
On Fri, 2003-10-31 at 16:59, H. Peter Anvin wrote:
> From: H. Peter Anvin <hpa@zytor.com>
> MIME-Version: 1.0
> Content-Type: text/plain; charset=ISO-8859-1
> Content-Transfer-Encoding: 8bit
> X-Comment-To: Bob Chiodini <robert.chiodini-1@ksc.nasa.gov>
> Disclaimer: Not speaking for Transmeta in any way, shape, or form.
> Copyright: Copyright 2003 H. Peter Anvin - All Rights Reserved
>
> Followup to: <1067604362.5526.15.camel@tweedy.ksc.nasa.gov>
> By author: Bob Chiodini <robert.chiodini-1@ksc.nasa.gov>
> In newsgroup: linux.dev.kernel
> >
> > John,
> >
> > It does not appear that the kernel(s) will support the root fs on
> > tmpfs. Looking through the init kernel code: It boils down to a block
> > device with real major and minor number or NFS.
> >
>
> Baloney. See the SuperRescue CD, for example, for a distro which uses
> exactly this.
>
> -hpa
I stand corrected. I should have been clearer making this statement. I
did not see a mechanism for mounting a tmpfs in do_mounts.c, or main.c.
One question: I see that superrescue execs init and the end of
linuxrc. Does this cause the kernel initialization to yield in
handle_initrd(), until init exits (reboot/shutdown)?
Bob...
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: initrd help -- umounts root after pivot_root
2003-10-31 0:18 John R Moser
@ 2003-10-31 18:47 ` Chris Lingard
0 siblings, 0 replies; 6+ messages in thread
From: Chris Lingard @ 2003-10-31 18:47 UTC (permalink / raw)
To: Linux Kernel Mailing List
On Friday 31 October 2003 12:18 am, John R Moser wrote:
> Been trying with 2.4.20, 2.4.22, 2.6.0-test9, how the heck do I get this
> to work?
> I set everthing up on /dev/shm type tmpfs, then
> cd /dev/shm
> mkdir initrd
> pivot_root . initrd
Might be better to do something like:
mount -t devfs none /dev
mount -t proc none /proc
mkdir -p ram
mount -t tmpfs tmpfs /ram
cd /ram
mkdir proc cdrom
mount -t proc none /ram/proc
/mount_cdrom
This is the start of my linuxrc script and creates the future root at /ram
> Of course, the kernel unmounts / and then swears that it can't find init
> when the linuxrc exits.
>
> The documentation says that linuxrc should pivot_root to the real root in
> Documentation/initrd.txt so I thought that's what the script sholud do.
> Apparently the doc is bad/old.
man pivot_root
mkdir initrd
sbin/pivot_root . initrd
mount devfs -t devfs /dev
exec /usr/sbin/chroot . /sbin/init <dev/console >dev/console 2>&1
(These is no automatic call to /sbin/init)
The documentation is bad insofar as root=/dev/rd/0 now fails
Also you will need to search for a patch to umount your old /initrd. Please
feel free you email me direct for a very unofficial patch to linux-2.4.22
Chris Lingard
^ permalink raw reply [flat|nested] 6+ messages in thread
* initrd help -- umounts root after pivot_root
@ 2003-10-31 0:18 John R Moser
2003-10-31 18:47 ` Chris Lingard
0 siblings, 1 reply; 6+ messages in thread
From: John R Moser @ 2003-10-31 0:18 UTC (permalink / raw)
To: Linux Kernel Mailing List
Been trying with 2.4.20, 2.4.22, 2.6.0-test9, how the heck do I get this
to work?
I set everthing up on /dev/shm type tmpfs, then
cd /dev/shm
mkdir initrd
pivot_root . initrd
So yay, it's set up so that the cd is pointed to by a lotta links in
tmpfs, and the stuff that needs to be rw (like /etc) is on the tmpfs.
That's good.
Of course, the kernel unmounts / and then swears that it can't find init
when the linuxrc exits.
The documentation says that linuxrc should pivot_root to the real root in
Documentation/initrd.txt so I thought that's what the script sholud do.
Apparently the doc is bad/old.
Any ideas?
script follows.
====/linuxrc
#!/bin/sh
# linuxrc for Genoppix initrd
# Basicly mounts the cdrom, sets up rw stuff, spins the root image
# around to the root, and exits.
echo "Genoppix Initrd Loaded, linuxrc executing in 5 seconds..."
sleep 5
mount none -t proc /proc
echo "Mounting cdrom..."
CDROM="/dev/cdrom"
if [ ! -e $CDROM ]; then
CDROM="/dev/cdroms/cdrom0"
fi
mount $CDROM /mnt/root || (echo "FATAL: Cannot mount cdrom!" && sh)
echo "mounting tmpfs..."
mount none -t tmpfs /dev/shm || (echo "FATAL: Cannot mount tmpfs!" && sh)
echo "Building symlinks to cd root..."
cd /dev/shm
ln -s /mnt/root/* .
sleep 2.5
echo "Setting mnt and home to rw root..."
rm -f root home mnt
mkdir root home mnt
#echo "linking cdroot's new location to what will be cdroot's old
location..."
#ln -s /mnt/initrd/mnt/root /dev/shm/mnt/root
echo "mounting cdrom at new root..."
mount $CDROM /dev/shm/mnt/root
echo "Pivoting root to shared memory filesystem..."
cd /dev/shm
mkdir initrd
pivot_root . initrd || (echo "Cannot pivot root!" && sh)
mount -t proc none /proc
echo "copying /etc to a rw /etc..."
rm -f etc
mount -t devfs none /dev
cp -R /mnt/root/etc .
echo "Root pivoted, making users..."
sleep 1
echo "creating homes for default users..."
cd /home
mkdir jak
mkdir tails
mkdir fox
mkdir krystal
chgrp users *
chown jak jak
chown tails tails
chown fox fox
chown tails tails
chown krystal krystal
echo "exiting linuxrc and starting init ;)
^ permalink raw reply [flat|nested] 6+ messages in thread
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2003-10-31 12:46 initrd help -- umounts root after pivot_root Bob Chiodini
2003-10-31 18:13 ` Maciej Zenczykowski
2003-10-31 21:59 ` H. Peter Anvin
2003-11-03 13:47 ` Bob Chiodini
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2003-10-31 0:18 John R Moser
2003-10-31 18:47 ` Chris Lingard
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