Date: Fri, 13 Nov 1998 14:56:19 -0800 (PST) From: Julian Elischer <julian@whistle.com> To: zhihuizhang <bf20761@binghamton.edu> Cc: Archie Cobbs <archie@whistle.com>, freebsd-hackers@FreeBSD.ORG Subject: Re: More questions on DEVFS Message-ID: <Pine.BSF.3.95.981113145427.19321G-100000@current1.whistle.com> In-Reply-To: <Pine.SOL.L3.93.981113162310.22911A-100000@bingsun2>
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On Fri, 13 Nov 1998, zhihuizhang wrote: > > > > (1) As I understand it, special files can be created only by superuser via > > > mknod and file systems can only be mounted by superuser. I do not see any > > > reason why the superuser will mount the device file system multiple times > > > and possibly at different mount points. > > > > You might want to create a chroot()'d sub-space of your filesystem, > > and put devices in there for example.. > > > After thinking for quite a while, I still have two confusions: > > (1) I read the source code of chroot() in file vfs_syscalls.c. It takes a > path and change the fd_rdir (root directory) of the calling process. How > can the superuser process change the root directory of any other process? Chroot is only valid for your own process, and its descendants > > (2) By saying "put devices in there..", I guess it means that the > superuser mount the special device at some directory under the new root. > If we set up root directories for several processes, then we may need to > mount a certain device used by these processes several times. DEVFS can > be mounted multiple times to achieve this. However, multiple mounts of > a normal file system are NOT allowed. Am I right? That is correct though I think possibly multiple /proc filesystems might be ok.. > > Thanks for your response. > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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