Messages in this thread |  | | | Date | Fri, 9 Jan 1998 11:16:12 +1100 | | From | Richard Gooch <> | | Subject | Re: devfs |
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Alan Cox writes: > > The FSSTND (Linux filesystem standard document) suggests the possibility > > of a read-only root filesystem. Read-only filesystems help reduce the > > chance that mistakes, crashes, and crackers (evil hackers) might damage > > something. The Linux root filesystem can not be read-only because the > > normal /dev must be read-write to allow tty ownership changes. With the > > devfs, the root filesystem can be read-only. The current /dev could be > > trouble for Linux embedded in ROM. > > Firstly. The fsstnd does not say /dev has to reamin on the root fs. Its also > not really an issue for a ROM based Linux - you tend to unpack a compressed > image from expensive slow flash into cheap ramdisk
If you have an embedded system with a ROM-FS or a CD-ROM then your root FS is read-only. From my updated README:
You can get around this by creating a RAMDISC at boot time, making an ext2 filesystem in it, mounting it somewhere and copying the contents of /dev into it, then unmounting it and mounting it over /dev. A devfs is a cleaner way of solving this.
> > With devfs, the kernel can chown ptys back to root when a process > > does not need them anymore. The kernel might be able to let normal > > users chown their own pty or it might perform the chown automatically. > > This solvable in user space by having a single pty allocation daemon. The > tty/pty issue is irrelevant the wisdom or otherwise of a devfs.
True, you can do it with a user-space daemon. But you then have to change applications to call it. Devfs doesn't need application changes.
Regards,
Richard....
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