On 10 Sep 2010 at 2:25, Roland McGrath wrote: > > Brad, sorry, I have bad news. glibc sysconf(_SC_ARG_MAX) is implemented > > by hard coded RLIMIT_STACK/4 heuristics. That said, at least _now_, we > > can't change this even though you disliked. That said, we can't break > > userland even though userland library is very crazy. > > I'm sorry you think it's "very crazy" to implement the required > functionality in the only way available. POSIX requires that execve > fail with E2BIG when the ARG_MAX limit is exceeded. sysconf has to > return the correct actual limit that execve will enforce so that a > conforming application knows how much it can safely attempt to use. > Since the kernel uses the hard-coded RLIMIT_STACK/4 heuristic and does > not expose the true manifest limit any other way, sysconf has to > parallel the kernel's calculation. no it doesn't have to, similarly to how it doesn't have to hardcode _SC_PAGESIZE either, AT_PAGESZ tells userland what it needs to know and i think AT_ARGMAX could exist just as well. -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
