/dev/mem: No such file or directory

/dev/mem: No such file or directory

Postby kpmcfadden » Mon Dec 28, 2015 2:28 pm

I am trying to run a networking application that is native x86 32-bit. My platform is a Raspberry Pi 2 with latest Jessie Raspian running. I can install and run other applications like nginx as described in the ExaGear Desktop manual without problem. However when I try to run my application it loads ok and daemonizes, returning control back to my prompt. However, I periodically get the error message "/dev/mem: No such file or directory" on the console and the application runs at a constant 25% CPU without proceeding to normal operation.

When I try to look at /dev/mem in the exagear shell I see the following:

pi@raspberrypi:~ $ ls -l /dev/mem
ls: cannot access /dev/mem: No such file or directory
pi@raspberrypi:~ $ ls -l /dev
ls: cannot access /dev/mem: No such file or directory
total 0
crw------- 1 root root 10, 235 Dec 23 03:20 autofs
drwxr-xr-x 2 root root 640 Dec 23 03:20 block
crw------- 1 root root 10, 234 Dec 23 03:20 btrfs-control
drwxr-xr-x 3 root root 60 Dec 31 1969 bus
< ... removed ... >
brw-rw---- 1 root disk 7, 7 Dec 23 03:20 loop7
drwxr-xr-x 2 root root 60 Dec 23 03:20 mapper
c????????? ? ? ? ? ? mem
crw------- 1 root root 10, 59 Dec 23 03:20 memory_bandwidth
brw-rw---- 1 root disk 179, 0 Dec 23 03:20 mmcblk0
brw-rw---- 1 root disk 179, 1 Dec 23 03:20 mmcblk0p1
brw-rw---- 1 root disk 179, 2 Dec 23 03:20 mmcblk0p2
< ... removed ... >
prw-r----- 1 root adm 0 Dec 23 03:21 xconsole
crw-rw-rw- 1 root root 1, 5 Dec 23 03:20 zero
pi@raspberrypi:~ $

From outside the exagear shell /dev/mem looks fine

pi@raspberrypi:~ $ ls -l /dev/mem
crw-r----- 1 root kmem 1, 1 Dec 23 03:20 /dev/mem
pi@raspberrypi:~ $ ls -l /opt/exagear/images/debian-8-wine2g/dev/mem
crw-r--r-- 1 root root 1, 1 Nov 25 2014 /opt/exagear/images/debian-8-wine2g/dev/mem
pi@raspberrypi:~ $

Any suggestions or help for solving this problem are greatly appreciated.
kpmcfadden
 
Posts: 2
Joined: Mon Dec 28, 2015 2:13 pm

Re: /dev/mem: No such file or directory

Postby Armmaster » Tue Dec 29, 2015 11:16 am

Hi,

Currently in Exagear access to /dev/mem is forbidden. The reason is because direct access to physical memory from guest may led to unpredictable behaviour.
Actually some proper x86 /dev/mem/ emulation is needed here. As only very specific apps do such tricks we need to collect some real-life statistics to implement this functionality.
Could you describe a bit more what app are you trying to launch under Exagear and why does it need /dev/mem ?
Armmaster
 
Posts: 86
Joined: Thu Oct 02, 2014 11:27 am

Re: /dev/mem: No such file or directory

Postby kpmcfadden » Tue Dec 29, 2015 12:00 pm

Armmaster,

Thank you for your reply. The app I am trying to run is a software IP network router platform. Since I am a user and not the developer of the application I can't describe much about the requirements or why the application needs to access /dev/mem.

I do know that the console receives the following additional messages that may help explain the situation.

/dev/mem: No such file or directory
child status returned: 6
killed by signal 6
status = 6 restart for status=6

I can give you more details about this outside of the forum and perhaps even access to my platform. Please let me know if/how we can work this further.

Thanks
kpmcfadden
 
Posts: 2
Joined: Mon Dec 28, 2015 2:13 pm


Return to ExaGear Desktop

Who is online

Users browsing this forum: No registered users and 5 guests