On Tue, Jun 19, 2018 at 02:40:14PM +0800, 陈华才 wrote: > Hi, Paul, > > First of all, could you please check why linux-mips reject e-mails > from lemote.com? Of course I can send e-mails by gmail, but my gmail > can't receive e-mails from linux-mips since March, 2018. Could you please learn to use email? No top posting and wrap lines at 78 chars. > I have already read Documentation/memory-barriers.txt, but I don't > think we should define a smp_read_barrier_depends() for Loongson-3. > Because Loongson-3's behavior isn't like Alpha, and in syntax, this is > not a data-dependent issue. Agreed, this is not a data-dependency issue. > There is no document about Loongson-3's SFB. In my opinion, SFB looks > like the L0 cache but sometimes it is out of cache-coherent machanism > (L1 cache's cross-core coherency is maintained by hardware, but not > always true for SFB). smp_mb() is needed for smp_cond_load_acquire(), > but not every READ_ONCE(). Linux does _NOT_ support non-coherent SMP. If your system is not fully coherent, you're out of luck. But please, explain in excruciating detail what exactly you need that smp_mb for. If, like I posited in my previous email, it is to ensure remote store buffer flushes, then your machine is terminally broken.
