Messages in this thread | | | From | (H. Peter Anvin) | Subject | Re: devlinks: an alternative to devfs | Date | 7 Jan 1998 18:51:48 GMT |
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Followup to: <E0xpr8B-0000AN-00@dungeon.inka.de> By author: Andreas Jellinghaus <aj@dungeon.inka.de> In newsgroup: linux.dev.kernel > > sorry, but i don't think that 8 bit minor numbers are a big problem. >
I disagree. Look at SCSI disks, for example. Furthermore, 8 bit minors artificially mask some of the problems with devfs.
> > the problem of /dev is different : there is no good management software, > and the kernel doesn't do much to help manageing it (/proc/devices > exists, but contains only major numbers and not much information). >
That is definitely true. My personal opinion is that device drivers should be bundles of some sort, which should include either the device nodes or a program to generate them, the kernel module, and possibly other things necessary.
As far as pty's are concerned, I think it is going to be necessary to let the kernel create device nodes for them. However, this doesn't have to be a separate filesystem -- the kernel is perfectly capable of creating traditional on-disk device nodes, which don't have to reside in memory and naturally swap out to disk when not needed. The scheme I imagine is the following:
- The openpty() library function opens /dev/ptx, the master clone device (did I get the name right)? - The kernel allocates an unused pty pair, and at the same time mknod's /dev/pts/NN with the uid and gid of the current user, unless /dev/pts is setgid, in which case the gid is gotten from the parent directory (standard creation rules!) If it is already there, it is unlinked and recreated. - The openpty() library function does an ioctl() to find out the pty number; the slave device being /dev/pts/%d.
I'd vote against using a hybrid BSD/SysV naming scheme for pty's, although we may allow the BSD-ish tty's to remain for compatibility (probably using a different set of device numbers.)
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