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AR# 68412

2016.3 PetaLinux: Missing "/dev/shm" in ZC706 pre-built image

Description

After booting the 2016.3 ZC706 pre-built image, the "/dev/shm" folder is not available. However, this not the case in the 2014.4 build.

2014.4 BSP for ZC706:

Built with PetaLinux v2014.4 (Yocto 1.7) Xilinx-ZC706-2014_4 /dev/ttyPS0
Xilinx-ZC706-2014_4 login: root
Password:
login[908]: root login on 'ttyPS0'
root@Xilinx-ZC706-2014_4:~# cd /dev/shm
root@Xilinx-ZC706-2014_4:/dev/shm#

2016.3 BSP for ZC706:

PetaLinux 2016.3 Xilinx-ZC706-2016_3 /dev/ttyPS0
Xilinx-ZC706-2016_3 login: root
Password:
login[971]: root login on 'ttyPS0'
root@Xilinx-ZC706-2016_3:~# cd /dev/shm
-sh: cd: can't cd to /dev/shm
root@Xilinx-ZC706-2016_3:~#

In both the case, the pre-built image has the following kernel setting (Under General Settings) set to Y:

Use Full shmem filesystem = Y

Solution

Below are the steps you need to follow to update the rootfs. You will also need to follow the OSL flow and the files associated with it.

1) Download uramdisk.gz for the ZC706 board and place it in /tmp.

http://www.wiki.xilinx.com/Zynq+Releases

2) Convert the uramdisk to ramdisk:

$ dd if=./uramdisk.image.gz of=./ramdisk.image.gz skip=16 bs=4

3) Unzip the ramdisk:

$ gunzip ramdisk.image.gz

4) Run the following command:

$ cpio -i -F UNZIPPED FILE (ex: cpio -i -F ramdisk.image)

5) Add the following changes in the etc/init.d/rcS file:

$ mount -t devtmpfs devtmpfs /dev -o size=64k,mode=755
$ mkdir /dev/pts /dev/shm

6) Convert back to uramdisk.image.gz using the mkimage utility:

$ mkimage -A arm -T ramdisk -C gzip -d arm_ramdisk.image.gz uramdisk.image.gz

With this change you should now be able to see the /dev/shm folder.

AR# 68412
Date 12/21/2016
Status Active
Type General Article
Devices
Tools
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