So far Perl has been using the 'fast stdio' tricks if they have been available (meaning that Configure has been able to snoop the structure of the stdio buffers enough). Yes, stdio has still been used even in this era of brave new perlio. I now (change #19286) introduced two new Configure variables and a new policy with them. d_faststdio d_stdstdio && d_stdio_ptr_lval && (d_stdio_cnt_lval || d_stdio_ptr_lval_sets_cnt) or in "C": USE_STDIO_PTR && STDIO_PTR_LVALUE && (STDIO_CNT_LVALUE || STDIO_PTR_LVAL_SETS_CNT) usefaststdio If we have 'fast stdio', shall we use it? For pre-blead (like, say, maint), the answer is 'no', because of backward compatibility. For blead, the answer is 'yes', use 'perlio'. THIS CHANGE MAY BREAK THINGS. Especially XS code may crash and burn because of FILE* in typemaps or directly in the code. This change is effectively the same as PERLIO=perlio. (PERLIO=stdio will still command Perl to use stdio, if we have 'fast stdio', that is.) I have not yet tried to propagate this change to non-Configure lands, let's first see how this thing flies. -- Jarkko Hietaniemi <jhi@iki.fi> http://www.iki.fi/jhi/ "There is this special biologist word we use for 'stable'. It is 'dead'." -- Jack CohenThread Next