Re: [Qemu-devel] ARM Cortex-M issues

[Liviu Ionescu]

> On 30 Aug 2016, at 10:38, Peter Maydell <address@hidden> wrote:
> 
> ... the only thing
> you can do is test it on the RTOSes you have to hand.

which, in the end, is a highly effective way. it does not identifies bugs 
related to features not used by the RTOS, but otherwise it is even more 
effective in catching bugs, than when using real hardware, especially when the 
RTOS is under construction.

some will probably argue agains this statement, but in the last 6 moths I used 
QEMU **extensively** to develop µOS++, finally running 8h+ endurance tests.

not only that QEMU is incredibly robust, but due to the inherent high jitter of 
the timers (SysTick in my case), combined with the very high speed of the 
emulation, it increases the chance for interrupts to occur in "unexpected" 
moments, and so identify badly placed critical sections inside the RTOS (the 
common source of concern in young RTOSes).

it is true that I spent quite a lot of time on GNU ARM Eclipse QEMU, but it was 
worth every penny; I could not imagine developing µOS++ without the scripts 
running multiple semihosted tests in a loop, for hours and hours. you simply 
cannot do this effectively on a real hardware.


so, Bill, if NMI is the only missing feature for your use case, I suggest 
fixing it and running your RTOS tests on QEMU.


regards,

Liviu