My First Nios-II

Altera_Forum · ‎01-21-2005

Hi,

I am trying to run a really simple Nios-II application using the ISS. After starting execution, the application does not even reach main(), however.

Instead it decides to crash within the system initialization routines, specifically, in a strcmp() call. The ISS reports:

'cpu::nios2ModelRun: ERROR: [439] instruction fetch access to address 0x1af8 returned uninitialized memory (valid mask=0x0)',

...and that is the end of the show.

The C-statement causing the error is:

strcmp("hoi","la"); /* yes, I lacked inspiration in coming up with better string names */

And the assembly statement within strcmp() causing the error when single stepping over it is:

0x00001af8 <strcmp>: ldb r6,0(r4)

Now, the value of register r4 right before entering the offending assembly line is r4 = 0x402c. So the Nios-II is reading a byte from location 0x402c in memory.

At this specific location is the value:

format: (address) (hex contents) (ascii contents)

0x0000402c 68 6f 69 00 hoi.

One would say that reading this memory location would be perfectly legal... I wonder if it has to do with the remark 'valid mask=0x0' in the error message.

Anyone, any idea ?

Bye,

Roland Vossen.

------ info about my Nios-II system ---

Altera Nios II ISS Software Simulation Environment Version 2.0

Info : Successfully read SOPC Builder PTF file 'D:\altera\roland_designs\first_nios\rollator.ptf'

Info : The SOPC Builder system contains the following modules:

Info : Bus module 'cpu_instruction_master_bus' - avalon.dll

Info : Bus module 'cpu_data_master_bus' - avalon.dll

Info : Master module 'cpu' - altera_nios2.dll

Info : Slave module 'timer' - altera_avalon_timer.dll

Info : Address span: 0x8800-0x881F (cpu_data_master_bus)

Warning : SOPC Builder system component pio_led is not supported by the simulator. Simulation may be incorrect if your software attempts to access it

Info : Slave module 'pio_led' - altera_avalon_pio.dll

Info : Address span: 0x8840-0x884F (cpu_data_master_bus)

Info : Slave module 'onchip_ram' - altera_memory.dll

Info : Address span: 0x4000-0x7FFF (cpu_instruction_master_bus)

Info : Address span: 0x4000-0x7FFF (cpu_data_master_bus)

Info : Slave module 'onchip_rom' - altera_memory.dll

Info : Address span: 0x0000-0x3FFF (cpu_instruction_master_bus)

Info : Address span: 0x0000-0x3FFF (cpu_data_master_bus)

Info : Slave module 'uart_0' - altera_avalon_uart.dll

Info : Address span: 0x8820-0x883F (cpu_data_master_bus)

Info : The debugger will be attached to processor cpu on port 2342

Info : Configuring 'rollator' model

Info : PTF Setting uart_0/SYSTEM_BUILDER_INFO/Iss_Launch_Telnet="0" detected

Info : 'uart_0' character stream will be displayed in this window

Info : The host communication device for stdin is uart_0

Info : The host communication device for stdout is uart_0

Info : The host communication device for stderr is uart_0

Info : Running 'rollator' model

Error! : Failed memory access in component cpu - Reading data 0x12f1d0 from uninitialised memory (addr = 0x1af8)

Info : Component cpu's program has terminated

Info : Instructions executed = 439

Info : cpu simulation return code 1

Info : Exiting rollator model with return code 1 (0 fatal errors, 1 error, 1 warning)

cpu::nios2ModelRun: ERROR: [439] instruction fetch access to address 0x1af8 returned uninitialized memory (valid mask=0x0)

Altera_Forum · ‎01-25-2005

Roland,

The error message is complaining about the instruction fetch.

<div class='quotetop'>QUOTE </div>

--- Quote Start ---

ERROR: [439] instruction fetch access to address 0x1af8 returned uninitialized memory[/b]

--- Quote End ---

It sounds like the simulator's memory at 0x1af8 hasn't been initialized. The simulator realizes this when it fetches an instruction from that address.

<div class='quotetop'>QUOTE </div>

--- Quote Start ---

I wonder if it has to do with the remark 'valid mask=0x0' in the error message.[/b]

--- Quote End ---

I think that the value mask records which bytes of the memory have been initialized. 0x0 means an entirely uninitialized word.

Kerry

Altera_Forum · ‎01-31-2005

Hi,

Update: this problem was solved by upgrading from Nios-II V2.0 to Nios-II V2.1. Issue closed.

Bye,

Roland.