On 16/02/2017 18:23, Laszlo Ersek wrote: > On 02/16/17 17:58, Paolo Bonzini wrote: >> >> >> On 16/02/2017 17:30, Chad Joan wrote: >>> Hello, >>> >>> This is a one-line patch to the configure script that will allow QEMU to be >>> built on musl-libc based Linux systems. This problem is only noticeable >>> when QEMU is built with --enable-curses. >>> >>> Detailed reading material if you want to know where this came from: >>> https://bugs.gentoo.org/show_bug.cgi?id=609364 >> >> Hi, >> >> can you explain exactly which function is missing without >> -D_XOPEN_SOURCE=500? If it is curses' wide-char functions, why does it >> fail with musl but not with glibc? Is _XOPEN_SOURCE always defined by >> glibc if you have _D_GNU_SOURCE? > > It is not necessarily auto-defined, but the effect is "as if".
Ok, so the bug is that glibc _does_ auto-define _XOPEN_SOURCE: #ifdef _GNU_SOURCE # undef _ISOC95_SOURCE # define _ISOC95_SOURCE 1 # undef _ISOC99_SOURCE # define _ISOC99_SOURCE 1 # undef _ISOC11_SOURCE # define _ISOC11_SOURCE 1 # undef _POSIX_SOURCE # define _POSIX_SOURCE 1 # undef _POSIX_C_SOURCE # define _POSIX_C_SOURCE 200809L # undef _XOPEN_SOURCE # define _XOPEN_SOURCE 700 # undef _XOPEN_SOURCE_EXTENDED # define _XOPEN_SOURCE_EXTENDED 1 # undef _LARGEFILE64_SOURCE # define _LARGEFILE64_SOURCE 1 # undef _DEFAULT_SOURCE # define _DEFAULT_SOURCE 1 # undef _ATFILE_SOURCE # define _ATFILE_SOURCE 1 #endif and ncursesw looks for _XOPEN_SOURCE exclusively: #ifndef NCURSES_WIDECHAR #if defined(_XOPEN_SOURCE_EXTENDED) || (defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE - 0 >= 500)) #define NCURSES_WIDECHAR 1 #else #define NCURSES_WIDECHAR 0 #endif #endif /* NCURSES_WIDECHAR */ So I do think that if musl wants to support _GNU_SOURCE, it should also auto-define; however it doesn't, see https://git.musl-libc.org/cgit/musl/tree/include/features.h. Alternatively, ncurses should be patched to look at _GNU_SOURCE in addition to _XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED. In any case, it's not a QEMU bug. Other packages likely are going to have the same issue, and fixing all of them is the wrong course of action. Paolo
