[Qemu-devel] [Bug 1636126] Re: qemu-system-arm segfaults on "smulbb r7, r5, r5"

[Peter Maydell]

Hi. This command line:

/opt/qemu-system-arm -M integratorcp -cpu cortex-m3 ...

is wrong. The integratorcp board is not a Cortex-M3 and trying to stick
one into it produces something that is not likely to work very well.
Please can you either (a) using a board that's expected to support a
Cortex-M3, like the lm3s6965evb or lm3s811evb, or (b) using the
integratorcp's default CPU if that's what your guest code is supposed to
run on. This sort of frankenstein combination is not supported...

That said, your problem here is that the SMULBB instruction is part of
the M profile DSP extension, which is not implemented in the Cortex-M3
(it first appears in the -M4). Not UNDEFing on the DSP instructions in
our Cortex-M3 model was a bug in QEMU v2.2 which we have subsequently
fixed.

You should build your guest code to target the CPU you're trying to run
it on.

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https://bugs.launchpad.net/bugs/1636126

Title:
  qemu-system-arm segfaults on "smulbb r7, r5, r5"

Status in QEMU:
  New

Bug description:
  I'll attach a binary that runs fine with qemu-system-arm V2.2.0 but V2.7.0 
segfaults.
  By stepping through with gdb I found that the segfaults happens when 
executing the line "smulbb r7, r5, r5" (where r7=0x1, r5=0x12).
  I'll also attach a debugger screenshot.

  call and output:

  /opt/qemu-system-arm -M integratorcp -cpu cortex-m3 -semihosting
  -nographic -monitor null -serial null -no-reboot -kernel
  0MFW_SafetyFunctions_ParameteruP1_CUNIT.elf

  ------------ CUnit_MFW_SafetyFunctions_Parameter ------------

  
       CUnit - A Unit testing framework for C - Version 2.1-0
       http://cunit.sourceforge.net/

  
  Suite: Suite_MFW_SafetyFunctions_Parameter
    Test: MFW_SafetyFunctions_Parameter_PositionLimiter ... Segmentation fault 
(core dumped)

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