[microblaze-uclinux] Microblaze bootloop question

[david moloney <moloned@xxxxxx>]

The following simple program works fine when downloaded to BRAM either 
from the EDK as part of the bitstream or via XMD as a file using dow 
simple/executable.elf.

main() {
 int i=1;
 while (i) {
   xil_printf("hello world! %d\n\r",i++);
 }
}

Downloading the bitstream via XMD into the external SDRAM with 
bootloader rather than application initialization in BRAM as suggested 
in Chapter 9 of the Xilinx User Guide and executing the following 
sequence of XMD commands below results (see end of mail) in the program 
being stuck in a loop in the bootloader (look at the rrd and stp 
commands below) code created automatically by the BSB for the NuHorizons 
Spartan3 board.

.section ".boot","ax"

_boot:  bri 0

Would I be right in that I need to change the bootloader from the 
default one in C:\EDK\sw\lib\microblaze\src called mb_bootloop.s and/or 
the associated linker script mb_bootloop.linkerscript?  

If so does anyone have such a bootloop or can you suggest how I can 
modify the existing one to work with my board which has its SDRAM 
located at 0x81800000.

Regards,

- David


XMD trace below:

Xilinx Microprocessor Debug (XMD) Engine
Xilinx EDK 6.2 Build EDK_Gm.11
Copyright (c) 1995-2002 Xilinx, Inc.  All rights reserved.
XMD% mbconnect mdm
Connecting to cable (Parallel Port - LPT1).
Checking cable driver.
Driver windrvr6.sys version = 6.0.3.0. LPT base address = 0378h.
ECP base address = 0778h.
Cable connection established.

JTAG chain configuration
--------------------------------------------------
Device   ID Code        IR Length    Part Name
1       05046093           8        XCF04S
2       0141c093           6        XC3S400
Assuming, Device No: 2 contains the MicroBlaze system
Connected to the JTAG MicroBlaze Debug Module (MDM)
No of processors = 1

MicroBlaze Processor 1 Configuration :
-------------------------------------
Version............................2.00.a
No of PC Breakpoints...............2
No of Read Addr/Data Watchpoints...1
No of Write Addr/Data Watchpoints..1
Instruction Cache Support..........off
Data Cache Support.................off
WARNING:: MHS file not specified..
       Cannot Check Microblaze-MDM FSL Connectivity !!
INFO:: No MHS,Assuming No MDM-FSL-MB Connection
JTAG MDM Connected to Mircoblaze 1
Connected to MicroBlaze "mdm" target. id = 0
Starting GDB server for "mdm" target (id = 0) at TCP port no 1234
XMD% dow -data simple/executable.elf 0x81800000
XMD% rrd
   r0: 00000000      r8: 00000000     r16: 00000000     r24: 00000000
   r1: 00000000      r9: 00000000     r17: 00000000     r25: 00000000
   r2: 00000000     r10: 00000000     r18: 00000000     r26: 00000000
   r3: 00000000     r11: 00000000     r19: 00000000     r27: 00000000
   r4: 00000000     r12: 00000000     r20: 00000000     r28: 00000000
   r5: 00000000     r13: 00000000     r21: 00000000     r29: 00000000
   r6: 00000000     r14: 00000000     r22: 00000000     r30: 00000000
   r7: 00000000     r15: 00000000     r23: 00000000     r31: 00000000
   pc: 00000000     msr: 00000000
XMD% stp
BREAKPOINT at
      0:   B8000000  bri     0
XMD% stp
BREAKPOINT at
      0:   B8000000  bri     0
XMD% stp
BREAKPOINT at
      0:   B8000000  bri     0
XMD% rrd
   r0: 00000000      r8: 00000000     r16: 00000000     r24: 00000000
   r1: 00000000      r9: 00000000     r17: 00000000     r25: 00000000
   r2: 00000000     r10: 00000000     r18: 00000000     r26: 00000000
   r3: 00000000     r11: 00000000     r19: 00000000     r27: 00000000
   r4: 00000000     r12: 00000000     r20: 00000000     r28: 00000000
   r5: 00000000     r13: 00000000     r21: 00000000     r29: 00000000
   r6: 00000000     r14: 00000000     r22: 00000000     r30: 00000000
   r7: 00000000     r15: 00000000     r23: 00000000     r31: 00000000
   pc: 00000000     msr: 00000000
XMD% run
Processor started. Type "stop" to stop processor
RUNNING> stop
XMD%
Processor stopped at PC: 0x00008000
XMD% rrd
   r0: 00000000      r8: 00000000     r16: 00000000     r24: 00000000
   r1: 00000000      r9: 00000000     r17: 00000000     r25: 00000000
   r2: 00000000     r10: 00000000     r18: 00000000     r26: 00000000
   r3: 00000000     r11: 00000000     r19: 00000000     r27: 00000000
   r4: 00000000     r12: 00000000     r20: 00000000     r28: 00000000
   r5: 00000000     r13: 00000000     r21: 00000000     r29: 00000000
   r6: 00000000     r14: 00000000     r22: 00000000     r30: 00000000
   r7: 00000000     r15: 00000000     r23: 00000000     r31: 00000000
   pc: 00008000     msr: 00000000
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