MIDAS - The Multiple Instance Data Acquisition System

Linux for the Xilinx Virtex4/5 FPGAs

(1) Introduction

This document describes how to obtain and build a Linux system for use in the PowerPC processor core of a Xilinx Virtex4/5 FPGA.
Specific boards for which Linux systems have been built are the Xilinx reference boards ML403, ML405 (Virtex 4) and ML507 (Virtex 5).
Specific installation and build steps are given for the installation on the system nnlxb at Daresbury.

(2) Embedded Linux Development Linux (ELDK)

The first step is to obtain and install the EDLK for the required PowerPC processor. The Virtex 4 PPC core is a PPC 405 processor and the Virtex 5 PPC core is a PPC 440 processor.

Obtain the ELDK from the DENX web site. The most recent version is 4.2 and this is the iso image for use with a Linux X86 host.
This contains the ELDK for the ppc_4xx processors (405 and 440) and the ppc_74xx processor (used in MVME5500).
Burn the iso image to a DVD or use the file directly as a DVD (for example VMware).
Mount in your Linux system using something like:
```
mount -o exec /dev/cdrom /media/cdrom
```
Install. This can be done using any desired ID; it does not have to be done using the superuser ID.
On nnlxb create the directory /opt/ELDK/4.2
To install for ppc405 and ppc440:
```
cd /media/cdrom
./install -d /opt/ELDK/4.2  ppc_4xx
cd /opt/ELDK/4.2
```
The next step DOES have to be performed using the superuser ID.
```
cd /opt/ELDK/4.2
bash eldk_init 4xx
/media/cdrom/ELDK_FIXOWNER  -a ppc_4xx
/media/cdrom/ELDK_MAKEDEV -a ppc_4xx
```
These steps can be repeated for other processor types such as ppc_74xx

A root filesystem suitable for Virtex4/5 can now be found in /opt/ELDK/4.2/ppc_4xx.
Cross compilers and other tools needed to built a Linux kernel can be found in /opt/ELDK/4.2/usr/bin.
The command bash /opt/ELDK/4.2/eldk_init 4xx sets the environment variables ARCH, CROSS_COMPILE and PATH needed for building the Linux kernel.
Alternatively using csh the command is source /opt/ELDK/4.2/ELDK.csh

(3) Embedded Linux Kernel

The PowerPC processors 405 and 440 and the architecture powerpc have now been merged into the mainstream Linux distribution (as of release 2.6.28). The last Linux release which supports the architecture ppc is 2.6.25. Both use the ELDK obtained above.
Since release 2.6.28 introduces a new way to handle devices embedded into the fabric of the FPGA (such as ethernet and all "user" devices) both 2.6.25 (ML403) and 2.6.28 (ML405 and ML507) are currently in use.

Obtain the Linux distribution from the Xilinx Open Source Wiki site and more specifically the Xilinx projects page.
For the latest release (currently 2.6.31) locate the project linux-2.6-xlnx.git and select tree. Then select snapshot. Save the file linux-2.6-xlnx.git-HEAD.tar.gz. Extract the compressed tarball and make it the directory structure /opt/SoftDev/Xilinx/linux-2.6.31.

Remember to setup the ELDK using bash /opt/ELDK/4.2/eldk_init 4xx or source /opt/ELDK/4.2/ELDK.csh.
Alternatively add the following to an initialise script
```
   setenv ARCH powerpc
   setenv CROSS_COMPILE ppc_4xx-

   if ($?PATH) then
      setenv PATH /opt/ELDK/4.2/usr/bin:/opt/ELDK/4.2/bin:${PATH}
   else
      setenv PATH /opt/ELDK/4.2/usr/bin:/opt/ELDK/4.2/bin
   endif
    
```
[Note: At Daresbury the Linux installation for the ML507 is /opt/SoftDev/Xilinx/linux-2.6.31/ml507 and for the AIDA board is /opt/SoftDev/Xilinx/linux-2.6.31/aida]
The following commands will then build a Linux kernel for the ML507 board.
A default Linux configuration is taken from the file arch/powerpc/configs/44x/ml507_defconfig The target to be built is defined by CONFIG_EXTRA_TARGETS="simpleImage.virtex440-ml507". The boot-time command line CONFIG_CMDLINE="" is actually defined later.
```
cd /opt/SoftDev/Xilinx/linux-2.6.31/ml507
make ARCH=powerpc 44x/ml507_defconfig
make ARCH=powerpc zImage
```
The Linux kernel will be in the file arch/powerpc/boot/simpleImage.virtex440-ml507.elf

Release 2.6.28 of Linux introduces the Device Tree feature which attempts to pull together the options from the FPGA code which are required by the corresponding Linux drivers.
The device tree file for the ML507 is arch/powerpc/boot/dts/virtex440-ml507.dts. This is combined with the Linux kernel as the very last step of the kernel build to make the elf file.
The device tree file contains options such as the default boot-time command line and the ethernet MAC address.
In the Daresbury installation the default command line parameter is bootargs = "console=ttyS0 ip=on root=/dev/nfs rw". The ethernet MAC address needs to be set correctly since it is used by DHCP to obtain Linux boot options such as the IP address and location of the NFS Root File System.
The following commands will then build a Linux kernel for the AIDA board.
A default Linux configuration is taken from the file arch/powerpc/configs/44x/aida_defconfig The target to be built is defined by CONFIG_EXTRA_TARGETS="simpleImage.virtex440-ml507". The boot-time command line CONFIG_CMDLINE="" is actually defined later.
```
cd /opt/SoftDev/Xilinx/linux-2.6.31/aida
make ARCH=powerpc 44x/aida_defconfig
make ARCH=powerpc zImage
```
The Linux kernel will be in the file arch/powerpc/boot/simpleImage.virtex440-ml507.elf
The device tree file for the AIDA board is arch/powerpc/boot/dts/virtex440-ml507.dts.

(4) Building the System ACE file

At Daresbury we elect (at least for the development phase) to load the Linux kernel using System ACE from a Compact Flash card as supported by all the Xilinx reference boards.
This requires that the elf file generated by the Linux build is combined with a bitstream (.bit) file generated by Xilinx EDK.
Xilinx ISE and EDK are installed on nnlxb in /opt/Xilinx/10.1.

Move the bitstream file generated by EDK for your ML507 project to /opt/SoftDev/Xilinx/linux-2.6.31/ml507/implementation/ml507_download.bit.
A reference design for the ML507 which contains a bitstream file suitable for use with the default Linux system can be obtained from Xilinx. Follow the link ML507 BlueCat Linux PPC440 Project. Look for the file ml507_ppc440_emb_ref/ready_for_download/download.bit.
Then use the following commands to run xmd and generate the ace file.
```
source /opt/Xilinx/10.1/ISE.csh
source /opt/Xilinx/10.1/EDK.csh
cd /opt/SoftDev/Xilinx/linux-2.6.31/ml507/implementation
xmd -tcl genace.tcl -opt genace_507.opt
```
The ace file will be in the file linux.ace and can then be copied to a Compact Flash card.
The xmd options file looks like:
```
-jprog
-hw /opt/SoftDev/Xilinx/linux-2.6.31/ml507/implementation/ml507_download.bit
-ace linux.ace
-board ml507
-elf /opt/SoftDev/Xilinx/linux-2.6.31/ml507/arch/powerpc/boot/simpleImage.virtex440-ml507.elf
-target ppc_hw
```

(5) ML405

A Linux kernel for the ML405 is obtained using the same procedure as described for the ML507 above.
[Note: At Daresbury the Linux installation for the ML405 is /opt/SoftDev/Xilinx/linux-2.6.28-rc6/ml405]

The default Linux configuration is taken from the file arch/powerpc/configs/40x/virtex4_defconfig.
The target to be built is defined by CONFIG_EXTRA_TARGETS="simpleImage.virtex405-ml405".

The following commands build the Linux kernel.
```
cd /opt/SoftDev/Xilinx/linux-2.6.28-rc6/ml405
make ARCH=powerpc 40x/virtex4_defconfig
make ARCH=powerpc zImage
```
The Linux kernel will be in the file arch/powerpc/boot/simpleImage.virtex405-ml405.elf
The device tree file for the ML405 is arch/powerpc/boot/dts/virtex405-ml405.dts
A reference bitstream file is available from the Xilinx Open Source Wiki site. Click on files at the bottom right hand corner of the page and download the file ml405_rtos_dma.bit.
[Note: The ml507 files here are no longer useful]

Build the linux.ace file from the generated elf file and the bitstream file as for the ML507 replacing ml507 with ml405 everywhere.

(6) ML403

A Linux kernel for the ML403 is currently obtained using the older (pre Device Tree) structure and the architecture ARCH=ppc. The last Linux release for which this is supported is 2.6.25-rc9.

Obtain the Linux distribution from the Xilinx Open Source Wiki site and more specifically the Xilinx projects page.
For the last release containing ARCH=ppc (2.6.25-rc9) locate the project linux-2.6-xlnx.git and select summary. Locate heads lin26-xlnx and select tree. Then select snapshot. Save the file linux-2.6-xlnx.git-lin26-xlnx.tar.gz. Extract the compressed tarball and make it the directory structure /opt/SoftDev/Xilinx/linux-2.6.25-rc9.

[Note: At Daresbury the Linux installation for the ML403 is named /opt/SoftDev/Xilinx/linux-2.6.25-xlnx]

The default Linux configuration is taken from the file arch/ppc/configs/ml403_defconfig.
The following configuration has been used at Daresbury and is generated from the defconfig file by the first step of the Linux kernel build. It is the file .config in the root of the Linux distribution.

For this release the information in the device tree file (.dts) above is supplied by the file arch/ppc/platforms/4xx/xparameters/xparameters_ml403.h which is compatible with the above .config file.
The corresponding bitstream file is download.bit

The Linux kernel for the ML403 can be built using the same method as for the ML507 and ML403.
```
cd /opt/SoftDev/Xilinx/linux-2.6.25-xlnx
make ARCH=ppc zImage
```
The system.ace file is then built using the file arch/ppc/boot/images/zImage.elf and the bitstream file download.bit.

Version 1.1 V Pucknell, STFC, Daresbury Lab. Oct 30 2009