Hi Ben, Cc: ghc-devs, I'm trying to build GHC head on OS X Mavericks with Xcode 5. 72f8b8d694362890a424f5fa21fef37cee921ecf introduced _SC_PHYS_PAGES. "man 3 sysconf" of OS X says that _SC_PHYS_PAGES exists. But actually I cannot find it in unistd.h. This is one of the problems which I hit up on now. Would you suggest me any workarounds? --Kazu