[Qemu-devel] [Bug 550863] Re: MicroBlaze QEMU skips jumps when using single steps in GDB

[Edgar E. Iglesias]

Hi,

I've committed a patch (that I hope fixes this problem) into the qemu
git repo.

Cheers

Look for the following commit:
commit 6c5f738daec123020d32543fe90a6633a4f6643e
Author: Edgar E. Iglesias <address@hidden>
Date:   Thu Feb 10 00:46:09 2011 +0100

    microblaze: Handle singlestepping over direct jmps
    
    Signed-off-by: Edgar E. Iglesias <address@hidden>

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https://bugs.launchpad.net/bugs/550863

Title:
  MicroBlaze QEMU skips jumps when using single steps in GDB

Status in QEMU:
  Fix Committed

Bug description:
  I'm trying to debug a MicroBlaze application (with the MicroBlaze
  system qemu, not the user mode qemu) using GDB. When I'm trying to
  single step through instructions all the branches are ignored: the
  program counter is just incremented by 4 (default), even for
  unconditional branches. This only occurs when using single step mode,
  everything runs as expected when using breakpoints only.

  Qemu Versions tested: 0.11.0, 0.12.3, GIT version (March 29, 2010)
  Qemu command used: qemu-system-microblaze -kernel test.elf  -S -s

  GDB Versions used: 7.1 (official MicroBlaze support), 6.5 (from Xilinx EDK 
10.1), 5.3 (from Xilinx EDK 9.1)
  GCC Versions used: 4.1.1 (from Xilinx EDK 11.1)

  I've attached my program, it uses a custom linker script and startup
  code. It runs fine without using singlestep mode.

  The bug looks similar to one submitted for PPC a while ago (181951).