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". It is documented in the libc info: https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html#index-_005fXOPEN_005fSOURCE > Macro: _XOPEN_SOURCE > Macro: _XOPEN_SOURCE_EXTENDED > > If you define this macro, functionality described in the X/Open > Portability Guide is included. This is a superset of the POSIX.1 > and POSIX.2 functionality and in fact _POSIX_SOURCE and > _POSIX_C_SOURCE are automatically defined. > > As the unification of all Unices, functionality only available in > BSD and SVID is also included. > > If the macro _XOPEN_SOURCE_EXTENDED is also defined, even more > functionality is available. The extra functions will make all > functions available which are necessary for the X/Open Unix brand. > > If the macro _XOPEN_SOURCE has the value 500 this includes all > functionality described so far plus some new definitions from the > Single Unix Specification, version 2. https://www.gnu.org/software/libc/manual/html_node/Feature-Test-Macros.html#index-_005fGNU_005fSOURCE > Macro: _GNU_SOURCE > > If you define this macro, everything is included: ISO C89, ISO > C99, POSIX.1, POSIX.2, BSD, SVID, X/Open, LFS, and GNU extensions. > In the cases where POSIX.1 conflicts with BSD, the POSIX > definitions take precedence. Curiously, I managed to recall this from years ago, when I was still living and breathing the SUS (and looking frequently at the glibc info too). Laszlo
