David Miller wrote: > From: Ingo Molnar <mingo@xxxxxxx> > Date: Tue, 26 Aug 2008 09:22:20 +0200 > >> And i guess the next generation of 4K CPUs support should just get away >> from cpumask_t-on-kernel-stack model altogether, as the current model is >> not maintainable. We tried the on-kernel-stack variant, and it really >> does not work reliably. We can fix this in v2.6.28. > > I recently did some work on sparc64 to use cpumask pointers > as much as possible. > > The only case that didn't work was due to a limitation in > arch interfaces for the new generic smp_call_function() code. > It passes a cpumask_t instead of a pointer to one via > arch_send_call_function_ipi(). > > But other than that, the whole sparc64 SMP stuff uses cpumask_t > pointers only. > > What it comes down to is that you have to do the "self cpu" > and other tests in the cross-call dispatch routines themselves, > instead of at the top-level working on cpumask_t objects. > > Otherwise you have to modify cpumask_t objects and thus pluck > them onto the stack where they take up silly amounts of space. Yes, I had proposed either modifying, or supplementing a new smp_call function to pass the cpumask_t as a pointer (similar to set_cpus_allowed_ptr.) But an ABI change such as this was not well received at the time. Thanks, Mike -- To unsubscribe from this list: send the line "unsubscribe kernel-testers" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
