On 09 Feb 2012, at 02:38, Matthew Gretton-Dann wrote:

> On Wed, Feb 08, 2012 at 10:35:48PM +0000, Jonas Maebe wrote:
>>
>> The full QEMU command line I use:
>>
>> ~/qemu/bin/qemu-system-arm -nographic -semihosting -M realview-eb - 
>> cpu cortex-m3 -kernel qsort_large -append "input_large.dat" -S -s
>
> I think -M realview-eb -cpu cortex-m3 is not the best way of  
> invoking qemu
> as it generates a system with a Cortex-M3 but without the appropriate
> interrupt controller.  Try one of the Stellaris boards instead (use
> -machine ? to get the actual command line).

I've now tried both -M lm3s811evb (Stellaris LM3S811EVB) and -M  
lm3s6965evb (Stellaris LM3S6965EVB) together with -cpu cortex-m3.  
Neither appears to work at all: there's no output (not even QEMU  
complaining that it can't open any sound devices, which it does  
instantaneously on startup if I choose the realview-eb platform).

If I start QEMU with a Stellaris platform selected and with -S -s  
(stop immediately on startup and wait for gdb) and attach gdb, the  
process is stopped at address 0 (instead of 0x8000). Removing the - 
semihosting switch does not change this (that would obviously fail as  
soon as a syscall were executed, but it doesn't get that far).

> We need to diagnose whether this is a QEmu or GDB issue.

Yes, I'm also starting to wonder whether I might be QEMU rather than  
gdb that's going wrong...

> What QEmu are you using?

The main site's 1.0 release, manually compiled directly from source  
(on Linux/x86-64).

> Can you clarify whether this is Cortex-M3 specific?  Does it happen  
> if you
> build for a Cortex-A profile CPU in ARM and Thumb state?  What  
> happens when
> you run the image in QEmu without GDB attached?

If I run it in QEMU (with -m realview-eb -cpu cortex-m3) without gdb  
attached, everything works correctly (although occasionally not all  
output is printed, but that's probably a QEMU issue). I currently  
can't rebuild it for Cortex-A or anything else because our license for  
RVCT has expired and we're still in the process of renewing it.

> Can you also provide a gdb trace of the remote protocol (use set debug
> remote on before attaching to QEmu).


I've attached the remote log for the qsort_large program I've  
compiled. The binary was started with the following QEMU command line:

~/qemu/bin/qemu-system-arm -nographic -semihosting -M realview-eb -cpu  
cortex-m3 -kernel qsort_large -append "input_large.dat" -s -S

I've also attached the qsort_large binary itself, since it's pretty  
small (and it's from mibench, so it's freely distributable). The  
input_large.dat file that's required for input can be gotten from http://www.eecs.umich.edu/mibench/automotive.tar.gz 
  (automotive/qsort/input_large.dat)

Thanks,


Jonas