[Buildroot] /tmp puzzle

[Charles Krinke]

Dear andy:

Thank you. That confirms my experiments. I have gotten sem_open() to
work and the key is that there *must* be a either a /dev/shm or a
"tmpfs" accessible via /proc/mounts.

I ended up disabling CONFIG_DEVTMPFS as after looking at all the
mpc83x_defconfig's in the kernels from 2.6.32 through 2.6.39, they all
have CONFIG_DEVTMPFS=n.

So, I am doing a completly clean build of the rootfilesystem and the
kernel to see if it actually, er, mounts properly after a make clean.

Thank you kindly, everyone.

On Mon, Jul 11, 2011 at 2:06 PM, ANDY KENNEDY <ANDY.KENNEDY at adtran.com> wrote:
>> I need to ask a slighly different question in my desire to
>> understand
>> what is going on.
>
> the config should be something like:
> CONFIG_SHMEM=y
> # CONFIG_DEVTMPFS is not set
> # CONFIG_SENSORS_TMP102 is not set
> # CONFIG_SENSORS_TMP401 is not set
> # CONFIG_SENSORS_TMP421 is not set
> CONFIG_TMPFS=y
> CONFIG_TMPFS_POSIX_ACL=y
>
> These two options are found in the following two locations:
> General setup  --->
>  [*] Configure standard kernel features (for small systems)  --->
>    -*-   Use full shmem filesystem
>
> File systems  --->
>  Pseudo filesystems  --->
>    -*- Virtual memory file system support (former shm fs)
>
> Earlier, you posted something about CONFIG_DEVTMPFS, but that
> is not the same thing as CONFIG_TMPFS.
>
> HTH,
> Andy
>
>>
>> If I disable "devtmpfs", I build my kernel and rootfilesystem and
>> when
>> it is mounted, I have a /tmp directory with *stuff* in it, but it
>> is
>> mounted at /var/tmp. I dont understand how /tmp got mounted. Would
>> someone be willing to help me understand how "/tmp" got mounted
>> when
>> it is not in the result of "mount" ?
>>
>> # cat /etc/fstab
>> # /etc/fstab: static file system information.
>> #
>> # <file system> <mount pt>     <type>   <options>         <dump>
>> <pass>
>> /dev/root       /              jffs2    rw,noauto         0      1
>> proc            /proc          proc     defaults          0      0
>> devpts          /dev/pts       devpts   defaults,gid=5,mode=620   0
>> 0
>> tmpfs           /tmp           tmpfs    defaults          0      0
>> sysfs           /sys           sysfs    defaults          0      0
>>
>> # mount
>> rootfs on / type rootfs (rw)
>> /dev/root on / type jffs2 (rw,relatime)
>> proc on /proc type proc (rw,relatime)
>> devpts on /dev/pts type devpts (rw,relatime,gid=5,mode=620)
>> sysfs on /sys type sysfs (rw,relatime)
>>
>> # mount -a
>> mount: mounting tmpfs on /tmp failed: Invalid argument
>> #
>>
>> # ls /tmp
>> dropbear.pid     log              sshd
>> ifstate          messages         subsys
>> ldconfig         portmap_mapping  utmp
>> #
>>
>> --
>> Charles Krinke
>> _______________________________________________
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>> buildroot at busybox.net
>> http://lists.busybox.net/mailman/listinfo/buildroot
>



-- 
Charles Krinke