Kernel config options (/dev, /dev/pts)

jrdioko · 08-20-2005, 10:30 PM

I'm recompiling my 2.4.26 kernel on Slack 10.0, and there's a few options I've seen various opinions on online. For the below two, what exactly are they and should they be enabled or disabled?

/dev file system support (EXPERIMENTAL)
/dev/pts file system for Unix98 PTYs

LiNuCe · 08-21-2005, 02:18 AM

Quote:

jrdioko :
I'm recompiling my 2.4.26 kernel on Slack 10.0, and there's a few options I've seen various opinions on online. For the below two, what exactly are they and should they be enabled or disabled?

/dev file system support (EXPERIMENTAL)
/dev/pts file system for Unix98 PTYs

The first kernel configuration option (DevFS) should be disabled : DevFS is obsolete as it is not maintained anymore. The second kernel configuration option, the Pseudo Terminals Filesystem (DevPts), is used to manage pseudo terminals devices and should be enabled : most pseudo terminals programs like XTerm, RXVT, GNOME Terminal and Konsole do need it.

If you enable DevFS, you don't need to enable DevPts as DevFS can replace it. By default, Slackware Linux tries to mount DevPts when it starts as there is a entry in /etc/fstab.

-- LiNuCe

jrdioko · 08-21-2005, 01:23 PM

Ok, and that's how I have it now. What is the difference, then, between devfs, the normal /dev structure that all Linux systems seem to have, and udev? (in simple terms, please)

cathectic · 08-21-2005, 01:33 PM

At the most basic, udev dynamically generates all device nodes based on rules on startup or when a device is plugged in, devfs is static.

See the udev FAQ for more.

jrdioko · 08-21-2005, 02:25 PM

What does a system use if both udev and devfs are disabled?

LiNuCe · 08-22-2005, 01:25 AM

Quote:

jrdioko: What does a system use if both udev and devfs are disabled?

It uses the traditionnal /dev directory hierarchy like most Unix operating system. It contains all necessary files which allow programs to access your hardware. These files are special character/block "nodes" (see the mknod(1) manual page) which are characterized by a major and minor number. You can look at the Linux allocated device list to search node/device associations and major/minor number allocations.

-- LiNuCe