fstab had usbfs and sysfs in Slackware 12.0 but not in 12.1

Z038 · 06-22-2008, 11:58 AM

I was comparing my fstab from a clean install of 12.1 to my fstab from a system that has been upgraded from 10.2 to 11.0 to 12.0 and I noticed that my old fstab had this:

Code:

usbfs         /proc/bus/usb   usbfs    user,defaults    0 0
none          /sys            sysfs    defaults         0 0

They are not in the fstab that was built by my clean install of 12.1. Maybe I added them to my old system manually or they were automatically added by a previous version of Slackware; I don't recall.

What did these do for me in previous versions of Slackware before 12.1, and why aren't they included in fstab by the 12.1 install?

Bruce Hill · 06-23-2008, 01:45 AM

Slackware-12.1 mounts them directly via rc scripts, and no longer requires the lines in /etc/fstab.

Alien Bob · 06-23-2008, 08:36 AM

Run "mount"... what does it tell you? You're not supposed to mess with it anymore, that is why it is no longer in /etc/fstab where you could easily remove the lines.

Eric

wadsworth · 06-23-2008, 08:47 AM

What's the output of "mount"?

Code:

$ mount
/dev/hda13 on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
usbfs on /proc/bus/usb type usbfs (rw)
/dev/hda14 on /home type ext3 (rw)
/dev/hda15 on /mnt/hda15 type ext3 (rw)
tmpfs on /dev/shm type tmpfs (rw)

They're mounted for me, just not mentioned in fstab.
(sorry, guess I should refresh the page before posting)

Z038 · 06-23-2008, 09:24 AM

Thanks. I surely won't mess with it. My results look pretty much like wadsworth's.

Code:

root@i1:~# mount
/dev/mapper/vg00-root on / type ext3 (rw)
proc on /proc type proc (rw)
sysfs on /sys type sysfs (rw)
usbfs on /proc/bus/usb type usbfs (rw)
/dev/mapper/vg00-home on /home type ext3 (rw)
/dev/sda1 on /boot type ext3 (rw)
/dev/hda1 on /mnt/hda1 type ext3 (rw)
/dev/hda5 on /mnt/hda5 type reiserfs (rw)
/dev/hdb1 /mnt/winxp type fuseblk (rw,nousid,nodev,noatime,allow_other,default_permissions,blksize=4096)
tmpfs on /dev/shm type tmpfs (rw)

tmpfs is new for 12.1 too, I believe. I guess that's a temporary file system, but what for?

Jins · 08-06-2008, 01:29 AM

tmpfs file system is for ATI driver to use 3D acceleration DRI.
without it users can't use it.

bgeddy · 08-06-2008, 09:35 AM

Have a look at /usr/src/linux/Documentation/filesystems/tmpfs.txt here is a quote from it:

Quote:

tmpfs has the following uses:

1) There is always a kernel internal mount which you will not see at
all. This is used for shared anonymous mappings and SYSV shared
memory.

This mount does not depend on CONFIG_TMPFS. If CONFIG_TMPFS is not
set, the user visible part of tmpfs is not build. But the internal
mechanisms are always present.

2) glibc 2.2 and above expects tmpfs to be mounted at /dev/shm for
POSIX shared memory (shm_open, shm_unlink). Adding the following
line to /etc/fstab should take care of this:

tmpfs /dev/shm tmpfs defaults 0 0

Remember to create the directory that you intend to mount tmpfs on
if necessary.

This mount is _not_ needed for SYSV shared memory. The internal
mount is used for that. (In the 2.3 kernel versions it was
necessary to mount the predecessor of tmpfs (shm fs) to use SYSV
shared memory)

3) Some people (including me) find it very convenient to mount it
e.g. on /tmp and /var/tmp and have a big swap partition. And now
loop mounts of tmpfs files do work, so mkinitrd shipped by most
distributions should succeed with a tmpfs /tmp.

4) And probably a lot more I do not know about :-)