Re: pivot_root alternative
On Mon, 25 Jun 2007 14:19:02 +0400 Michael Tokarev <[EMAIL PROTECTED]> wrote: > Salvatore De Paolis wrote: > > > >> use run-init from klibc? > > > > Thank you both, i'll take a look at run-init:) > > By the way, busybox now includes similar applet, > named switch_root. > > /mjt yeah, i saw it yesterday after a while. Anyway the problem got a solution, everything seems to work just fine. Regards S. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
Salvatore De Paolis wrote: > >> use run-init from klibc? > > Thank you both, i'll take a look at run-init:) By the way, busybox now includes similar applet, named switch_root. /mjt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
Salvatore De Paolis wrote: use run-init from klibc? Thank you both, i'll take a look at run-init:) By the way, busybox now includes similar applet, named switch_root. /mjt - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
On Mon, 25 Jun 2007 14:19:02 +0400 Michael Tokarev [EMAIL PROTECTED] wrote: Salvatore De Paolis wrote: use run-init from klibc? Thank you both, i'll take a look at run-init:) By the way, busybox now includes similar applet, named switch_root. /mjt yeah, i saw it yesterday after a while. Anyway the problem got a solution, everything seems to work just fine. Regards S. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
So i choice to use switch_root which is already inside the busybox but with a bit(?) of unluck cause it still wont run. It hangs on !S_ISREG(st1.st_mode) Can you explain to me how to interpret it? Regards S. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
Arnd Hannemann wrote: > Jan Engelhardt schrieb: >> On Jun 24 2007 23:27, Salvatore De Paolis wrote: >>> i built the kernel with a busybox initramfs which runs from a usb stick. >>> While >>> i boot i need to mount the real root and i'm using pivot_root. >>> Pivot_root . old-root return to me an "Invalid argument" error and googling >>> i >>> found here http://lkml.org/lkml/2005/10/8/17 that pivot_root should be >>> avoided. >>> I want to ask now what i should do to switch to a real root? >> use run-init from klibc? > > However be aware of the limitation of run-init: > It only works for direct childs of root directory > /mnt/newroot won't work > /newroot should work ;-) > Hm, that should probably be fixed. It should be able to work on any directory as long as there isn't another *filesystem* involved... -hpa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
On Jun 24, 2007, at 17:27:34, Salvatore De Paolis wrote:
i built the kernel with a busybox initramfs which runs from a usb
stick. While i boot i need to mount the real root and i'm using
pivot_root. Pivot_root . old-root return to me an "Invalid
argument" error and googling i found here http://lkml.org/lkml/
2005/10/8/17 that pivot_root should be avoided. I want to ask now
what i should do to switch to a real root?
One interesting fact about the mount() syscall is this: when
overmounting a directory tree, a process whose current working
directory is within said directory tree will see the old vfsmounts
until it does an absolute chdir(). Shells tend not to be terribly
useful for this because they use absolute paths more than necessary,
but I think you can make it work. For instance, if you run these
commands after mounting the root filesystem:
mount -t proc proc /realroot/proc
cd /
mount --move /realroot /
find /proc/$$/cwd/ -mindepth 1 -maxdepth 1 -print0 \
| xargs -0 rm -rf -- '{}' ';'
cd /
This will set up proc on the new root filesystem, move /realroot to
the root directory, and delete the contents of the old initramfs
using the old current-working-directory link of your shell. The
amusing thing is that you are using the "find" and "rm" commands from
the newly mounted root filesystem to remove the contents of the
completely hidden initramfs. The only reason it's actually possible
is because you have the tenuous thread of the working directory.
Cheers,
Kyle Moffett
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
On Sun, 24 Jun 2007 23:39:25 +0200 Arnd Hannemann <[EMAIL PROTECTED]> wrote: > use run-init from klibc? > However be aware of the limitation of run-init: > It only works for direct childs of root directory > /mnt/newroot won't work > /newroot should work ;-) > > Good luck, > Arnd Thank you both, i'll take a look at run-init:) Nice to know about the child limitation but i just have to find klibc-utils inside buildroot or busybox if even exists:) Regards S. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
Jan Engelhardt schrieb: > On Jun 24 2007 23:27, Salvatore De Paolis wrote: >> i built the kernel with a busybox initramfs which runs from a usb stick. >> While >> i boot i need to mount the real root and i'm using pivot_root. >> Pivot_root . old-root return to me an "Invalid argument" error and googling i >> found here http://lkml.org/lkml/2005/10/8/17 that pivot_root should be >> avoided. >> I want to ask now what i should do to switch to a real root? > > use run-init from klibc? However be aware of the limitation of run-init: It only works for direct childs of root directory /mnt/newroot won't work /newroot should work ;-) Good luck, Arnd - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
On Jun 24 2007 23:27, Salvatore De Paolis wrote: > >i built the kernel with a busybox initramfs which runs from a usb stick. While >i boot i need to mount the real root and i'm using pivot_root. >Pivot_root . old-root return to me an "Invalid argument" error and googling i >found here http://lkml.org/lkml/2005/10/8/17 that pivot_root should be avoided. >I want to ask now what i should do to switch to a real root? use run-init from klibc? Jan -- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
On Jun 24 2007 23:27, Salvatore De Paolis wrote: i built the kernel with a busybox initramfs which runs from a usb stick. While i boot i need to mount the real root and i'm using pivot_root. Pivot_root . old-root return to me an Invalid argument error and googling i found here http://lkml.org/lkml/2005/10/8/17 that pivot_root should be avoided. I want to ask now what i should do to switch to a real root? use run-init from klibc? Jan -- - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
Jan Engelhardt schrieb: On Jun 24 2007 23:27, Salvatore De Paolis wrote: i built the kernel with a busybox initramfs which runs from a usb stick. While i boot i need to mount the real root and i'm using pivot_root. Pivot_root . old-root return to me an Invalid argument error and googling i found here http://lkml.org/lkml/2005/10/8/17 that pivot_root should be avoided. I want to ask now what i should do to switch to a real root? use run-init from klibc? However be aware of the limitation of run-init: It only works for direct childs of root directory /mnt/newroot won't work /newroot should work ;-) Good luck, Arnd - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
On Sun, 24 Jun 2007 23:39:25 +0200 Arnd Hannemann [EMAIL PROTECTED] wrote: use run-init from klibc? However be aware of the limitation of run-init: It only works for direct childs of root directory /mnt/newroot won't work /newroot should work ;-) Good luck, Arnd Thank you both, i'll take a look at run-init:) Nice to know about the child limitation but i just have to find klibc-utils inside buildroot or busybox if even exists:) Regards S. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
On Jun 24, 2007, at 17:27:34, Salvatore De Paolis wrote:
i built the kernel with a busybox initramfs which runs from a usb
stick. While i boot i need to mount the real root and i'm using
pivot_root. Pivot_root . old-root return to me an Invalid
argument error and googling i found here http://lkml.org/lkml/
2005/10/8/17 that pivot_root should be avoided. I want to ask now
what i should do to switch to a real root?
One interesting fact about the mount() syscall is this: when
overmounting a directory tree, a process whose current working
directory is within said directory tree will see the old vfsmounts
until it does an absolute chdir(). Shells tend not to be terribly
useful for this because they use absolute paths more than necessary,
but I think you can make it work. For instance, if you run these
commands after mounting the root filesystem:
mount -t proc proc /realroot/proc
cd /
mount --move /realroot /
find /proc/$$/cwd/ -mindepth 1 -maxdepth 1 -print0 \
| xargs -0 rm -rf -- '{}' ';'
cd /
This will set up proc on the new root filesystem, move /realroot to
the root directory, and delete the contents of the old initramfs
using the old current-working-directory link of your shell. The
amusing thing is that you are using the find and rm commands from
the newly mounted root filesystem to remove the contents of the
completely hidden initramfs. The only reason it's actually possible
is because you have the tenuous thread of the working directory.
Cheers,
Kyle Moffett
-
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
Arnd Hannemann wrote: Jan Engelhardt schrieb: On Jun 24 2007 23:27, Salvatore De Paolis wrote: i built the kernel with a busybox initramfs which runs from a usb stick. While i boot i need to mount the real root and i'm using pivot_root. Pivot_root . old-root return to me an Invalid argument error and googling i found here http://lkml.org/lkml/2005/10/8/17 that pivot_root should be avoided. I want to ask now what i should do to switch to a real root? use run-init from klibc? However be aware of the limitation of run-init: It only works for direct childs of root directory /mnt/newroot won't work /newroot should work ;-) Hm, that should probably be fixed. It should be able to work on any directory as long as there isn't another *filesystem* involved... -hpa - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: pivot_root alternative
So i choice to use switch_root which is already inside the busybox but with a bit(?) of unluck cause it still wont run. It hangs on !S_ISREG(st1.st_mode) Can you explain to me how to interpret it? Regards S. - To unsubscribe from this list: send the line unsubscribe linux-kernel in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
