Hi Andrew,
On 11 May 2015 at 12:17, Andrew Jones <[email protected]> wrote:
> > +
> > +void atomic_lock(int *lock_var)
> > +{
> > + while (__sync_lock_test_and_set(lock_var, 1));
> > +}
> > +
> > +void atomic_unlock(int *lock_var)
> > +{
> > + __sync_lock_release(lock_var);
> > +}
>
> Do these builtins actually do anything without enabling the
> MMU first?
>From my experience while testing on ARM, without the builtins
atomicity will fail, with our without enabling the MMU.
> > +
> > +void test_spinlock()
> > +{
> > + int i, errors = 0;
> > + int cpu = get_cpuid();
> > +
> > + for (i = 0; i < LOOP_SIZE; i++) {
> > + LOCK(&global_lock);
> > +
> > + if (global_a == (cpu + 1) % 2) {
> > + global_a = 1;
> > + global_b = 0;
> > + } else {
> > + global_a = 0;
> > + global_b = 1;
> > + }
> > +
> > + if (global_a == global_b) {
> > + errors++;
> > + }
> > + UNLOCK(&global_lock);
> > + }
> > +
> > + printf("CPU%d: Done - Errors: %d\n", cpu, errors);
> > +}
> > +
> > void main(void)
> > {
> > - printf("CPU %d on\n", get_cpuid());
> > + if (!get_cpuid()) {
> > + printf("Starting test\n");
> > + }
> > +
> > + test_spinlock();
> > power_off();
> > }
>
> You could have saved a ton of time by just putting these 50
> lines into a new kvm-unit-tests test. If you need the mmu
> disabled for some reason, then we can add an mmu_disable()
> to the API.
>
> drew
The main idea is to start with something very minimal and
straightforward for a standalone test similar to the QEMU's multiboot,
since the target is to mainly trigger race conditions and test
multithreaded TCG.
Thanks.
