Richard Henderson <r...@twiddle.net> writes: > On 11/10/2016 05:14 PM, Alex Bennée wrote: >> Even worse than that we trip up the atomic.h QEMU_BUILD_BUG_ON with the >> atomic_cmpxchg. Now I believe we can use atomic_cmpxchg__nocheck without >> too much issue on x86 but we'll need to #ifdef it on detection of wide >> atomics. > > You've already got CONFIG_ATOMIC64. And what's the fallback?
I'm going to re-factor cputlb a bit so all the TLB read and write's can be done in helper functions so I don't scatter stuff around too much. I was thinking something like: #ifdef CONFIG_ATOMIC64 .. as usual .. #else assert(!parallel_cpus) .. non atomic update .. #endif > We ought not be enabling mttcg for 32-bit host and 64-bit guest at all. But > that doesn't help much here, where we're otherwise guest width > agnostic. Hmm well the most common case (any guest on x86) should work. Currently the default mttcg code in cpus.c works when: #if defined(CONFIG_MTTCG_TARGET) && defined(CONFIG_MTTCG_HOST) I should probably expand that to default to false in the case of (sizeof target_ulong > sizeof void *) when we don't have CONFIG_ATOMIC64. Then if the user does force mttcg on they will quickly get an assert although maybe we want to report that in a nicer way? > > > r~ -- Alex Bennée
