mdev problem with BB 1.4.2
Thomas Mathys
tmathys at hsr.ch
Wed Apr 18 17:29:56 UTC 2007
Hello,
I had this problem too when I upgraded to a recent kernel, where sysfs
heavily changed. The problem is, that mdev does never follow symlinks
(probably to keep mdev simple - sysfs is full of cycles caused by symlinks).
I did find a fix (forgive me for not sending it as a patch - I don't
have access to that code right now):
Inside mdev.c is a function that recursively traverses sysfs. It
descends only into entries that are NOT symlinks. I changed mdev.c, so
that it does not descend into symlinks, UNLESS they're called subsystem.
Explanation:
- I observed that all the missing device nodes can be reached by
following a symlink called subsystem
- And I observed that cycles in sysfs are never caused by the subsystem
symlinks
Cheers
Thomas Mathys
Mike Cashwell wrote:
> Greetings all,
>
> I'm bringing up a completely new toolchain (gcc 4.1.1; glibc 2.5;
> linux 2.6.20.4; BB 1.4.2) on an ARM v4tle board. (Whew!)
>
> I'm having trouble getting mdev to fully populate /dev. Specifically,
> I'm not getting entries for my 3 physical serial ports. I've scoured
> the mailing list archives and found a few near-misses, but nothing
> specific.
>
> My hunch is that my sysfs is putting in symlinks in such a way that
> mdev is having trouble. I've included what I think is the relevant
> info below.
>
> Anyone have any ideas? Maybe there's some BB config setting I don't
> have set? My confusion is why mdev is getting the block devices right
> but not the character ones.
>
> Thanks for any assistance!
> -Mike
>
> ------ /dev and /sys info -----
>
> dm17:/dev $ ls -la
> drwxrwxrwt 4 root root 640 Jan 1 00:01 .
> drwxrwxr-x 15 500 500 4096 Apr 18 2007 ..
> crw------- 1 root root 5, 1 Jan 1 04:58 console
> srw-rw-rw- 1 root root 0 Jan 1 00:01 log
> brw-rw---- 1 root root 7, 0 Jan 1 00:01 loop0
> brw-rw---- 1 root root 7, 1 Jan 1 00:01 loop1
> brw-rw---- 1 root root 7, 2 Jan 1 00:01 loop2
> brw-rw---- 1 root root 7, 3 Jan 1 00:01 loop3
> brw-rw---- 1 root root 7, 4 Jan 1 00:01 loop4
> brw-rw---- 1 root root 7, 5 Jan 1 00:01 loop5
> brw-rw---- 1 root root 7, 6 Jan 1 00:01 loop6
> brw-rw---- 1 root root 7, 7 Jan 1 00:01 loop7
> crw-r--r-- 1 root root 1, 3 Jan 1 00:00 null
> drwxr-xr-x 2 root root 40 Jan 1 00:00 pts
> brw-rw---- 1 root root 1, 0 Jan 1 00:01 ram0
> brw-rw---- 1 root root 1, 1 Jan 1 00:01 ram1
> brw-rw---- 1 root root 1, 10 Jan 1 00:01 ram10
> brw-rw---- 1 root root 1, 11 Jan 1 00:01 ram11
> brw-rw---- 1 root root 1, 12 Jan 1 00:01 ram12
> brw-rw---- 1 root root 1, 13 Jan 1 00:01 ram13
> brw-rw---- 1 root root 1, 14 Jan 1 00:01 ram14
> brw-rw---- 1 root root 1, 15 Jan 1 00:01 ram15
> brw-rw---- 1 root root 1, 2 Jan 1 00:01 ram2
> brw-rw---- 1 root root 1, 3 Jan 1 00:01 ram3
> brw-rw---- 1 root root 1, 4 Jan 1 00:01 ram4
> brw-rw---- 1 root root 1, 5 Jan 1 00:01 ram5
> brw-rw---- 1 root root 1, 6 Jan 1 00:01 ram6
> brw-rw---- 1 root root 1, 7 Jan 1 00:01 ram7
> brw-rw---- 1 root root 1, 8 Jan 1 00:01 ram8
> brw-rw---- 1 root root 1, 9 Jan 1 00:01 ram9
> crw-rw---- 1 root root 254, 0 Jan 1 00:01 rtc0
> drwxr-xr-x 2 root root 40 Jan 1 00:00 shm
> dm17:/dev $ cd /sys
> dm17:/sys $ ls
> block class firmware kernel power
> bus devices fs module
> dm17:/sys $ cd class/
> dm17:/sys/class $ ls -la
> drwxr-xr-x 9 root root 0 Jan 1 1970 .
> drwxr-xr-x 11 root root 0 Jan 1 1970 ..
> drwxr-xr-x 2 root root 0 Jan 1 00:01 mem
> drwxr-xr-x 2 root root 0 Jan 1 00:01 misc
> drwxr-xr-x 2 root root 0 Jan 1 1970 mtd
> drwxr-xr-x 4 root root 0 Jan 1 1970 net
> drwxr-xr-x 3 root root 0 Jan 1 1970 rtc
> drwxr-xr-x 3 root root 0 Jan 1 1970 rtc-dev
> drwxr-xr-x 2 root root 0 Jan 1 00:01 tty
> dm17:/sys/class $ cd tty/
> dm17:/sys/class/tty $ ls -la
> drwxr-xr-x 2 root root 0 Jan 1 00:01 .
> drwxr-xr-x 9 root root 0 Jan 1 1970 ..
> lrwxrwxrwx 1 root root 0 Jan 1 00:01 console -
> > ../../devices/virtual/tty/console
> lrwxrwxrwx 1 root root 0 Jan 1 00:01 ptmx -> ../../
> devices/virtual/tty/ptmx
> lrwxrwxrwx 1 root root 0 Jan 1 00:01 tty -> ../../
> devices/virtual/tty/tty
> lrwxrwxrwx 1 root root 0 Jan 1 00:01 ttyS0 -
> > ../../devices/platform/serial8250.0/ttyS0
> lrwxrwxrwx 1 root root 0 Jan 1 00:01 ttyS1 -
> > ../../devices/platform/serial8250.0/ttyS1
> lrwxrwxrwx 1 root root 0 Jan 1 00:01 ttyS2 -
> > ../../devices/platform/serial8250.0/ttyS2
> dm17:/sys/class/tty $ cat ttyS0/dev
> 4:64
> dm17:/sys/class/tty $ cat /proc/devices
> Character devices:
> 1 mem
> 4 ttyS
> 5 /dev/tty
> 5 /dev/console
> 5 /dev/ptmx
> 10 misc
> 90 mtd
> 128 ptm
> 136 pts
> 254 rtc
>
> Block devices:
> 1 ramdisk
> 7 loop
> 31 mtdblock
>
>
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