New Horizons

Welcome to my blog

My name is Sven Andersson and I
work as a consultant in embedded
system design, implemented in ASIC
and FPGA.
In my spare time I write this blog
and I hope it will inspire others to
learn more about this fantastic field.
I live in Stockholm Sweden and have
my own company


You are welcome to contact me
and ask questions or make comments
about my blog.


New Horizons
What's new
Starting a blog
Writing a blog
Using an RSS reader

Zynq Design From Scratch
Started February 2014
1 Introduction
Changes and updates
2 Zynq-7000 All Programmable SoC
3 ZedBoard and other boards
4 Computer platform and VirtualBox
5 Installing Ubuntu
6 Fixing Ubuntu
7 Installing Vivado
8 Starting Vivado
9 Using Vivado
10 Lab 1. Create a Zynq project
11 Lab 1. Build a hardware platform
12 Lab 1. Create a software application
13 Lab 1. Connect to ZedBoard
14 Lab 1. Run a software application
15 Lab 1. Benchmarking ARM Cortex-A9
16 Lab 2. Adding a GPIO peripheral
17 Lab 2. Create a custom HDL module
18 Lab 2. Connect package pins and implement
19 Lab 2. Create a software application and configure the PL
20 Lab 2. Debugging a software application
21 Running Linux from SD card
22 Installing PetaLinux
23 Booting PetaLinux
24 Connect to ZedBoad via ethernet
25 Rebuilding the PetaLinux kernel image
26 Running a DHCP server on the host
27 Running a TFTP server on the host
28 PetaLinux boot via U-boot
29 PetaLinux application development
30 Fixing the host computer
31 Running NFS servers
32 VirtualBox seamless mode
33 Mounting guest file system using sshfs
34 PetaLinux. Setting up a web server
35 PetaLinux. Using cgi scripts
36 PetaLinux. Web enabled application
37 Convert from VirtualBox to VMware
38 Running Linaro Ubuntu on ZedBoard
39 Running Android on ZedBoard
40 Lab2. Booting from SD card and SPI flash
41 Lab2. PetaLinux board bringup
42 Lab2. Writing userspace IO device driver
43 Lab2. Hardware debugging
44 MicroZed quick start
45 Installing Vivado 2014.1
46 Lab3. Adding push buttons to our Zynq system
47 Lab3. Adding an interrupt service routine
48 Installing Ubuntu 14.04
49 Installing Vivado and Petalinux 2014.2
50 Using Vivado 2014.2
51 Upgrading to Ubuntu 14.04
52 Using Petalinux 2014.2
53 Booting from SD card and SPI flash
54 Booting Petalinux 2014.2 from SD card
55 Booting Petalinux 2014.2 from SPI flash
56 Installing Vivado 2014.3

Chipotle Verification System

EE Times Retrospective Series
It all started more than 40 years ago
My first job as an electrical engineer
The Memory (R)evolution
The Microprocessor (R)evolution

Four soft-core processors
Started January 2012
Table of contents
OpenRISC 1200
Nios II

Using the Spartan-6 LX9 MicroBoard
Started August 2011
Table of contents
Problems, fixes and solutions

FPGA Design From Scratch
Started December 2006
Table of contents
Acronyms and abbreviations

Actel FPGA design
Designing with an Actel FPGA. Part 1
Designing with an Actel FPGA. Part 2
Designing with an Actel FPGA. Part 3
Designing with an Actel FPGA. Part 4
Designing with an Actel FPGA. Part 5

A hardware designer's best friend
Zoo Design Platform

Installing Cobra Command Tool
A processor benchmark

Porting a Unix program to Mac OS X
Fixing a HyperTerminal in Mac OS X
A dream come true

Stockholm by bike

The New York City Marathon

Kittelfjall Lappland

Tour skating in Sweden and around the world
Wild skating
Tour day
Safety equipment
A look at the equipment you need
Skate maintenance
Books, photos, films and videos
Weather forecasts

38000 feet above see level
A trip to Spain
Florida the sunshine state

Photo Albums
Seaside Florida
Ronda Spain
Sevilla Spain
Cordoba Spain
Alhambra Spain
KittelfjÀll Lapland
Landsort Art Walk
Skating on thin ice

100 Power Tips for FPGA Designers

Adventures in ASIC
Computer History Museum
Design & Reuse
d9 Tech Blog
EDA Cafe
EDA DesignLine
Eli's tech Blog
FPGA Arcade
FPGA Central
FPGA developer
FPGA Journal
FPGA World
Lesley Shannon Courses
Mac 2 Ubuntu
Programmable Logic DesignLine
World of ASIC

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Friday, June 15, 2007
FPGA design from scratch. Part 34
Program disassembly

What happened to our c program after we compiled and built it. Let's disassemble the ETC_system_program.elf to find out. We will us the command mb-objdump -d ETC_system_program.elf. Here is the printout:

Assembly code

Disassembly of section .vectors.reset:

00000000 <_start>:
   0:    b8080050     brai    80               // 50 <_TEXT_START_ADDR>
Disassembly of section .vectors.sw_exception:

00000008 <_vector_sw_exception>:
   8:    b80801a0     brai    416              // 1a0 <_exception_handler>
Disassembly of section .vectors.interrupt:

00000010 <_vector_interrupt>:
  10:    b80801bc     brai    444              // 1bc <__interrupt_handler>
Disassembly of section .vectors.hw_exception:

00000020 <_vector_hw_exception>:
  20:    b80801b8     brai    440              // 1b8 <_hw_exception_handler>
Disassembly of section .text:

00000050 <_start1>:
  50:    31a003d0     addik    r13, r0, 976    // 3d0 <_SDA_BASE_>
  54:    304003b0     addik    r2, r0, 944     // 3b0 <_SDA2_BASE_>
  58:    30200750     addik    r1, r0, 1872
  5c:    b9f40088     brlid    r15, 136        // e4 <_crtinit>
  60:    80000000     or       r0, r0, r0
  64:    20210010     addi     r1, r1, 16

00000068 <exit>:
  68:    b8000000     bri      0               // 68 <exit>

0000006c <__do_global_dtors_aux>:
  6c:    e0600350     lbui     r3, r0, 848     // 350 <_essro>
  70:    3021ffe4     addik    r1, r1, -28
  74:    f9e10000     swi      r15, r1, 0
  78:    bc030014     beqi     r3, 20          // 8c
  7c:    b8000028     bri      40              // a4
  80:    f8600338     swi      r3, r0, 824     // 338 <p.0>
  84:    99fc2000     brald    r15, r4
  88:    80000000     or       r0, r0, r0
  8c:    e8600338     lwi      r3, r0, 824     // 338 <p.0>
  90:    e8830000     lwi      r4, r3, 0
  94:    be24ffec     bneid    r4, -20         // 80
  98:    30630004     addik    r3, r3, 4
  9c:    30600001     addik    r3, r0, 1
  a0:    f0600350     sbi      r3, r0, 848     // 350 <_essro>
  a4:    e9e10000     lwi      r15, r1, 0
  a8:    b60f0008     rtsd     r15, 8
  ac:    3021001c     addik    r1, r1, 28

000000b0 <frame_dummy>:
  b0:    e860034c     lwi      r3, r0, 844     // 34c <_edata>
  b4:    3021ffe4     addik    r1, r1, -28
  b8:    f9e10000     swi      r15, r1, 0
  bc:    bc03001c     beqi     r3, 28          // d8
  c0:    b0000000     imm      0
  c4:    30600000     addik    r3, r0, 0
  c8:    30a0034c     addik    r5, r0, 844     // 34c <_edata>
  cc:    bc03000c     beqi     r3, 12          // d8
  d0:    99fc1800     brald    r15, r3
  d4:    80000000     or       r0, r0, r0
  d8:    e9e10000     lwi      r15, r1, 0
  dc:    b60f0008     rtsd     r15, 8
  e0:    3021001c     addik    r1, r1, 28

000000e4 <_crtinit>:
  e4:    2021ffec     addi    r1, r1, -20
  e8:    f9e10000     swi     r15, r1, 0
  ec:    20c00350     addi    r6, r0, 848     // 350 <_essro>
  f0:    20e00350     addi    r7, r0, 848     // 350 <_essro>
  f4:    06463800     rsub    r18, r6, r7
  f8:    bc720014     blei    r18, 20         // 10c
  fc:    f8060000     swi     r0, r6, 0
 100:    20c60004     addi    r6, r6, 4
 104:    06463800     rsub    r18, r6, r7
 108:    bc92fff4     bgti    r18, -12        // fc
 10c:    20c00350     addi    r6, r0, 848     // 350 <_essro>
 110:    20e0035c     addi    r7, r0, 860     // 35c <__bss_end>
 114:    06463800     rsub    r18, r6, r7
 118:    bc720014     blei    r18, 20         // 12c
 11c:    f8060000     swi     r0, r6, 0
 120:    20c60004     addi    r6, r6, 4
 124:    06463800     rsub    r18, r6, r7
 128:    bc92fff4     bgti    r18, -12        // 11c
 12c:    b9f40084     brlid   r15, 132        // 1b0 <_program_init>
 130:    80000000     or      r0, r0, r0
 134:    b9f401ac     brlid   r15, 428        // 2e0 <_etext>
 138:    80000000     or      r0, r0, r0
 13c:    20c00000     addi    r6, r0, 0
 140:    20e00000     addi    r7, r0, 0
 144:    b9f40024     brlid   r15, 36         // 168 <main>
 148:    20a00000     addi    r5, r0, 0
 14c:    b9f401b8     brlid   r15, 440        // 304 <__fini>
 150:    80000000     or      r0, r0, r0
 154:    b9f40054     brlid   r15, 84         // 1a8 <_program_clean>
 158:    80000000     or      r0, r0, r0
 15c:    c9e10000     lw      r15, r1, r0
 160:    b60f0008     rtsd    r15, 8
 164:    20210014     addi    r1, r1, 20

00000168 <main>:
 168:    3021ffe8     addik   r1, r1, -24
 16c:    fa610014     swi     r19, r1, 20
 170:    12610000     addk    r19, r1, r0
 174:    b00041f0     imm     16880
 178:    f800c004     swi     r0, r0, -16380
 17c:    3060007f     addik   r3, r0, 127
 180:    b00041f0     imm     16880
 184:    f860c000     swi     r3, r0, -16384
 188:    b00041f0     imm     16880
 18c:    f800c000     swi     r0, r0, -16384
 190:    3060002a     addik   r3, r0, 42
 194:    b00041f0     imm     16880
 198:    f860c000     swi     r3, r0, -16384
 19c:    b8000000     bri     0                // 19c

000001a0 <_exception_handler>:
 1a0:    b6110000     rtsd    r17, 0
 1a4:    80000000     or      r0, r0, r0

000001a8 <_program_clean>:
 1a8:    b60f0008     rtsd   r15, 8
 1ac:    80000000     or     r0, r0, r0

000001b0 <_program_init>:
 1b0:    b60f0008     rtsd   r15, 8
 1b4:    80000000     or     r0, r0, r0

000001b8 <_hw_exception_handler>:
 1b8:    b8000000     bri    0                // 1b8 <_hw_exception_handler>

000001bc <__interrupt_handler>:
 1bc:    3021ffb0     addik  r1, r1, -80
 1c0:    f9e10000     swi    r15, r1, 0
 1c4:    f8610020     swi    r3, r1, 32
 1c8:    f8810024     swi    r4, r1, 36
 1cc:    f8a10028     swi    r5, r1, 40
 1d0:    f8c1002c     swi    r6, r1, 44
 1d4:    f8e10030     swi    r7, r1, 48
 1d8:    f9010034     swi    r8, r1, 52
 1dc:    f9210038     swi    r9, r1, 56
 1e0:    f941003c     swi    r10, r1, 60
 1e4:    f9610040     swi    r11, r1, 64
 1e8:    f9810044     swi    r12, r1, 68
 1ec:    fa210048     swi    r17, r1, 72
 1f0:    95608001     mfs    r11, rmsr
 1f4:    e8a00340     lwi    r5, r0, 832
 1f8:    e860033c     lwi    r3, r0, 828     // 33c <MB_InterruptVectorTable>
 1fc:    fa41004c     swi    r18, r1, 76
 200:    f961001c     swi    r11, r1, 28
 204:    99fc1800     brald  r15, r3
 208:    80000000     or     r0, r0, r0
 20c:    e9e10000     lwi    r15, r1, 0
 210:    e961001c     lwi    r11, r1, 28
 214:    e8610020     lwi    r3, r1, 32
 218:    e8810024     lwi    r4, r1, 36
 21c:    940bc001     mts    rmsr, r11
 220:    e8a10028     lwi    r5, r1, 40
 224:    e8c1002c     lwi    r6, r1, 44
 228:    e8e10030     lwi    r7, r1, 48
 22c:    e9010034     lwi    r8, r1, 52
 230:    e9210038     lwi    r9, r1, 56
 234:    e941003c     lwi    r10, r1, 60
 238:    e9610040     lwi    r11, r1, 64
 23c:    e9810044     lwi    r12, r1, 68
 240:    ea210048     lwi    r17, r1, 72
 244:    ea41004c     lwi    r18, r1, 76
 248:    b62e0000     rtid   r14, 0
 24c:    30210050     addik  r1, r1, 80

00000250 <microblaze_register_handler>:
 250:    f8a0033c     swi    r5, r0, 828     // 33c <MB_InterruptVectorTable>
 254:    f8c00340     swi    r6, r0, 832
 258:    b60f0008     rtsd   r15, 8
 25c:    80000000     or     r0, r0, r0

00000260 <XAssert>:
 260:    e8600354     lwi    r3, r0, 852     // 354 <XAssertCallbackRoutine>
 264:    3021ffe4     addik  r1, r1, -28
 268:    f9e10000     swi    r15, r1, 0
 26c:    bc230018     bnei   r3, 24          // 284
 270:    e8600344     lwi    r3, r0, 836     // 344 <XWaitInAssert>
 274:    bc230000     bnei   r3, 0           // 274
 278:    e9e10000     lwi    r15, r1, 0
 27c:    b60f0008     rtsd   r15, 8
 280:    3021001c     addik  r1, r1, 28
 284:    99fc1800     brald  r15, r3
 288:    80000000     or     r0, r0, r0
 28c:    b800ffe4     bri    -28             // 270

00000290 <XAssertSetCallback>:
 290:    f8a00354     swi    r5, r0, 852     // 354 <XAssertCallbackRoutine>
 294:    b60f0008     rtsd   r15, 8
 298:    80000000     or     r0, r0, r0

0000029c <XNullHandler>:
 29c:    b60f0008     rtsd   r15, 8
 2a0:    80000000     or     r0, r0, r0

000002a4 <__do_global_ctors_aux>:
 2a4:    3021ffe0     addik  r1, r1, -32
 2a8:    fa61001c     swi    r19, r1, 28
 2ac:    e8600320     lwi    r3, r0, 800     // 320 <__CTOR_LIST__>
 2b0:    32600320     addik  r19, r0, 800    // 320 <__CTOR_LIST__>
 2b4:    f9e10000     swi    r15, r1, 0
 2b8:    b8000010     bri    16              // 2c8
 2bc:    99fc1800     brald  r15, r3
 2c0:    3273fffc     addik  r19, r19, -4
 2c4:    e8730000     lwi    r3, r19, 0
 2c8:    aa43ffff     xori   r18, r3, -1
 2cc:    bc32fff0     bnei   r18, -16        // 2bc
 2d0:    e9e10000     lwi    r15, r1, 0
 2d4:    ea61001c     lwi    r19, r1, 28
 2d8:    b60f0008     rtsd   r15, 8
 2dc:    30210020     addik  r1, r1, 32
Disassembly of section .init:

000002e0 <__init>:
 2e0:    3021fff8     addik   r1, r1, -8
 2e4:    d9e00800     sw      r15, r0, r1
 2e8:    b9fc00b0     bralid  r15, 176      // b0 <frame_dummy>
 2ec:    80000000     or      r0, r0, r0
 2f0:    b9fc02a4     bralid  r15, 676      // 2a4 <__do_global_ctors_aux>
 2f4:    80000000     or      r0, r0, r0
 2f8:    c9e00800     lw      r15, r0, r1
 2fc:    b60f0008     rtsd    r15, 8
 300:    30210008     addik   r1, r1, 8
Disassembly of section .fini:

00000304 <__fini>:
 304:    3021fff8     addik   r1, r1, -8
 308:    d9e00800     sw      r15, r0, r1
 30c:    b9fc006c     bralid  r15, 108     // 6c <__do_global_dtors_aux>
 310:    80000000     or      r0, r0, r0
 314:    c9e00800     lw      r15, r0, r1
 318:    b60f0008     rtsd    r15, 8
 31c:    30210008     addik   r1, r1, 8

MicroBlaze Software Reference Guide

MicroBlaze Software Reference Guide will tell us all about writing software for the MicroBlaze soft processor.

System memory layout

How is the system memory allocated. Let's try to find out. Address range 0x00000000-0x0000004f is reserved for reset, exceptions, interrupt and break vectors.

Event Vector Address
Register File Return Address
Reset 0x00000000-0x00000004 -
User Vector (Exception)
0x00000008-0x0000000c Rx
Interrrupt 0x00000010-0x00000014  R14
0x00000018-0x0000001c  R16
Hardware Exception
0x00000020-0x00000024 R17 or BTR
Reserved by Xilinx for future use
0x00000028-0x0000004f -

To allow for 64 bit addressing two 32 bit worlds are reserved for each vector.

Reset sequence

When a Reset occurs, MicroBlaze flushes the pipeline and starts fetching instructions from the reset vector (address 0x0). The external reset signal is active high and should be asserted for a minimum of 16 cycles.

The branch instruction <b
rai  _TEXT_START_ADDR> stored in address 0x0 will be executed (see Simvision plot). _TEXT_START_ADDR marks the start of the executable code.

ELF file content

 C routine
exit End of program loop 
main Our program











Here are some more information about the different files used when compiling and linking a typical MicroBlaze executable.
Startup files

The compiler includes pre-compiled startup and end files in the final link command when forming an executable. Startup files set up the language and the platform environment before your application code executes. The following actions are typically performed by startup files:
  • Set up any reset, interrupt, and exception vectors as required.
  • Set up stack pointer, small-data anchors, and other registers. Refer to Table 10-9 for details.
  • Clear the BSS memory regions to zero.
  • Invoke language initialization functions, such as C++ constructors.
  • Initialize the hardware sub-system.
  • Set up arguments for the main procedure and invoke it.
Similarly, end files are used to include code that must execute after your program ends. The following actions are typically performed by end files:
  • Invoke language cleanup functions, such as C++ destructors.
  • De-initialize the hardware sub-system. For example, if the program is being profiled, clean up the profiling sub-system.
First stage initialization files


This initialization file is used for programs which are to be executed in standalone mode, without the use of any bootloader or debugging stub such as xmdstub. This CRT populates the reset, interrupt, exception, and hardware exception vectors and invokes the second stage startup routine _crtinit. On returning from _crtinit, it ends the program by infinitely looping in the exit label.

Second stage initialization files

According to the C standard specification, all global and static variables must be initialized to 0. This is a common functionality required by all the CRTs above. Another routine _crtinit is invoked. The _crtinit routine initializes memory in the .bss section of the program. _crtinit is also the wrapper that invokes the main procedure. Before invoking the main procedure, it may invoke other initialization functions. _crtinit is supplied by the following startup files, as described below.


This is the default second stage C startup file. This startup file performs the following steps:
  1. Clears the .bss section to zero.
  2.  Invokes _program_init.
  3.  Invokes "constructor" functions (__init).
  4. Sets up the arguments for main and invokes main.
  5. Invokes "destructor" functions (__fini).
  6. Invokes _program_clean and returns.

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