7 Updating RamDisk Image of Zybo

When the destination platform is Zybo Board, the code should be compiled for that Linux running on Zybo but there is something more to it.

Nacltai encryption library requires GLIBC library version 2.17 minimum, and arm-xilinx-linux-gnueabi- uses version 2.18, so it is okay at compilation time.

However, at run time the library files of the RAMDisk image are used, and there is no valid RAMDisk image released by Digilent yet. So one solution is to use arm_ramdisk.image.gz given by Xilinx here.

However, that RAMDisk image has older version of GLIBC loaded in its /lib directory, so it needs to be updated first. Also its size should be updated because new library will take more space.

Updating RAMDisk size

Modification is to update RAMDisk size that Kernel can use. So just edit CONFIG_BLK_DEV_RAM_SIZE parameter in /Linux-Digilent-Dev/.config to a size you want. The original size is 16384 (16MB), you can use 64 MB RAMDisk size like this.

CONFIG_BLK_DEV_RAM_SIZE=65536

After this change re-compile the kernel and create uImage file.

Updating Libraries

You can follow this page to edit a RAMDisk file.

The change needs to be done in step 3, is to remove old library files and change them with the library files of arm-xilinx-linux-gnueabi:

cd lib/
sudo rm -r ./*
sudo cp /opt/Xilinx/SDK/2014.3.1/gnu/arm/lin/arm-xilinx-linux-gnueabi/libc/lib/* ./*

Note that not only libc.so file corresponding to GLIBC library is updated, but all of the library files. That is to get all library files together with ld configration.