Re: Device file not appearing

[Gregory Anders <greg@gpanders.com>]

On Wed, 17 Mar 2021 10:56:34 -0600, Gregory Anders <greg@gpanders.com> wrote:
>I switched over to using the miscdevice API and the situation is the 
>same. Nothing under /dev, but I can see my device under /sys/dev/char 
>(it now also exists under /sys/devices/virtual/misc/, as expected).
>
>I verified that devtmpfs is enabled in the kernel config 
>(CONFIG_DEVTMPFS=y and CONFIG_DEVTMPFS_MOUNT=y) and also see that it 
>is mounted on /dev:
>
>    # cat /proc/mounts
>    root@xilinx-kcu105-2020_2:~# cat /proc/mounts
>    192.168.0.116:/data/nfs/root / nfs rw,relatime,vers=3,rsize=4096,wsize=4096,namlen=255,hard,nolock,proto=tcp,timeo=600,retrans=2,sec=sys,mountaddr=192.168.0.116,mountvers=3,mountproto=tcp,local_lock=all,addr=192.168.0.116 0 0
>    devtmpfs /dev devtmpfs rw,relatime,size=1026312k,nr_inodes=185478,mode=755 0 0
>    proc /proc proc rw,relatime 0 0
>    sysfs /sys sysfs rw,relatime 0 0
>    tmpfs /run tmpfs rw,nosuid,nodev,mode=755 0 0
>    tmpfs /var/volatile tmpfs rw,relatime 0 0
>    tmpfs /dev tmpfs rw,relatime,size=64k,mode=755 0 0
>    devpts /dev/pts devpts rw,relatime,mode=600,ptmxmode=000 0 0
>
>I notice that it lists /dev as both devtmpfs (line 2) as well as tmpfs 
>(the second line from the bottom). Could that be an issue? I'm not 
>sure how or why /dev is being mounted as tmpfs in addition to 
>devtmpfs.
>
>Thanks,
>
>Greg

One other data point: there are 3 other misc devices on the system, and 
all of them are correctly listed under /dev:

     # ls -1 /sys/class/misc
     cpu_dma_latency
     loop-control
     foo0
     vga_arbiter

     # ls -1 /dev/{cpu_dma_latency,loop-control,vga_arbiter}
     /dev/cpu_dma_latency
     /dev/loop-control
     /dev/vga_arbiter

Greg

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