Date: Tue, 15 Jul 2008 01:40:24 +0530 From: "Tapan Chaudhari" <tapan.list@gmail.com> To: freebsd-hackers@freebsd.org Subject: Re: Can I change the device of the "/" mount point at boot time. Message-ID: <482257ad0807141310h3381a97dif17290aed1133cfe@mail.gmail.com> In-Reply-To: <20080714153653.59ecb307@bhuda.mired.org> References: <482257ad0807141106m679ec19frd853339637d27a2d@mail.gmail.com> <20080714184030.GA62288@eos.sc1.parodius.com> <482257ad0807141218l26cbb95aid91414a3c88a121c@mail.gmail.com> <20080714153653.59ecb307@bhuda.mired.org>
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Hi, Thanks a lot Mike. But the problem is the device I am talking about is not the physical device. I am writing a driver which will create a virtual device and all the i/os done on this virtual device will be ultimately redirected to the original device. Correct me if I am wrong, but I guess the loader will try to mount my new device on '/' and then load the modules into the kernel. Since my driver would not be loaded at that point in time, it will fail to even mount '/'. Am I right? Or can our drivers get loaded before loader mounts '/' ? Thanks, --Tapan. On Tue, Jul 15, 2008 at 1:06 AM, Mike Meyer <mwm@mired.org> wrote: > On Tue, 15 Jul 2008 00:48:42 +0530 > "Tapan Chaudhari" <tapan.list@gmail.com> wrote: > > > This is not exactly what I wanted. I will try to elaborate myself. > > I am creating my own device which will act as a new boot slice which must > be > > mounted as '/'. New device will process i/o calls and then redirect the > i/o > > calls to original device of '/'. Now since I cannot unmount '/' and mount > it > > again with my new device while system is running, I will have to find a > way > > to tell kernel to mount my new device as '/' from next time onwards it > > boots. > > does anyone have suggestions on this? > > That's pretty much exactly what vfs.root.mountfrom does. Edit > /boot/loader.conf to add a line: > > vfs.root_mountfrom="fstype:devicespec" > > and you're good to go. The kernel will boot from your default root > partition, then remount root using the value of that variable. I.e. - > I set mine to "zfs:internal/root" to boot my system to a zfs root. > > <mike > -- > Mike Meyer <mwm@mired.org> > http://www.mired.org/consulting.html > Independent Network/Unix/Perforce consultant, email for more information. > > O< ascii ribbon campaign - stop html mail - www.asciiribbon.org >
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