Where is the CPU serializing instruction which must be executed before return
to user mode, so that kernel accesses to hardware devices are guaranteed to
complete before any subsequent user access begins? (Otherwise a read/write
by the user to a memory-mapped device page can appear out-of-order with respect
to the kernel accesses in a preceding syscall.) The only generally useful
serializing instructions are IRET and CPUID; only IRET is implemented univerally.
-- John Reiser, jreiser@BitWagon.com- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/