> Does anything except the vDSO actually use the vDSO data page? It's > mapped as part of the vDSO image (i.e. at a non-constant address), and > it's not immediate obvious how userspace would locate that page.
Just for reference - on ia64 the address of the entry point for the magic fast system call page is passed to each applications via the "auxv" structure that exec(2) drops at the top of stack after args/env in the AT_SYSINFO entry. Apps look for it to find out where to jump for fast system call entry (if it isn't there, they fall back to regular slow syscall path). Same method could be used to provide the address of a magic read-only for users page that kernel fills with stuff for simple system calls. -Tony -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
