Hi,
I have only recently started to use kernels with devfs enabled, and I
have some newbie questions. I don't know if this list is the right place
to ask them, but this is already my first question:
Is there a faq or howto for devfs, other than the far too short and
technical kernel source filesystems/devfs/README? By wading through
thousands of linux-kernel messages, I found some informations, so I am
now starting "devfsd /dev" at the beginning of rc.sysinit, and I have
learned from Doug Gilbert's page at
http://www.torque.net/sg/devfs_scsi.html how to open some security holes
so that I can login as root or start X as non-root.
But a couple of things still don't work, in particular my printer,
floppy, cd, and gpm, and this leads to 3 different questions:
1. My printer uses /dev/ttyS1, and when I used devfs for the first time
with kernel 2.3.51, there was no such device. Instead of ttyS0-3 there
was only a /dev/ttyS with major 4, minor 64. 3 days ago, I booted with a
kernel 2.3.52, and suddenly the devices ttyS0 and ttyS1 (which
correspond to the 2 serial ports I have) were back. Printing worked. Now
yesterday I booted with 2.3.99-pre2, and I was back to square one: no
ttyS1, only a ttyS. All 3 kernels used basically the same config options
and the same kernel command line, and devfsd was started automatically
in the same way. Where does this difference come from and how can I make
sure that devfsd creates ttyS0 and ttyS1 as, according to README, it is
supposed to do? Where does devfsd get its list of devices from? How does
it decide which ones to create?
2. There is no /dev/floppy nor fd0 or whatever. ToDo mentions that swim3
is not yet supported. I have a Pmac 6400, and swim3 is its floppy
controller. Is there any way to use this floppy with devfs? How hard is
it to add devfs support to drivers/block/swim3.c?
3. Gpm doesn't start because /dev/mouse is missing. Normally, this is a
symlink to /dev/adbmouse. If I make such a link, it will disappear upon
reboot. Same problem with /dev/cdrom, /dev/modem and many others that
are created either by some programs or by myself using mknod or
symlinks. Is there a way to tell devfsd about such things so that devfsd
recreates them at reboot? The documentation on devfsd (man devfsd) is
too rudimentary to know. Does one have to use the rc.devfs script and
store these informations in some tar file? Or is the recommended way
after all to use 2 directories, /devfs for devfs to play with, and /dev
for the use of the rest of the kernel with symlinks between the two?
These may be dumb questions, but if they don't have simple answers, I
shall have to say good-bye to devfs.
--
Martin
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