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Date: Tue, 19 Apr 2011 13:03:05 -0400 From: Arnaud Lacombe <lacombar@...il.com> To: Michal Marek <mmarek@...e.cz> Cc: Valentin Ochs <a@....de>, Roman Zippel <zippel@...ux-m68k.org>, trivial@...nel.org, linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: [PATCH v2] kconfig/kbuild: define _POSIX_C_SOURCE Hi, On Tue, Apr 19, 2011 at 5:54 AM, Michal Marek <mmarek@...e.cz> wrote: > On 10.4.2011 16:31, Valentin Ochs wrote: >> On Sat, Apr 09, 2011 at 11:34:00PM -0400, Arnaud Lacombe wrote: >>> On Sat, Apr 9, 2011 at 10:09 PM, Valentin Ochs <a@....de> wrote: >>>> The three patched files use PATH_MAX without defining the required >>>> _POSIX_C_SOURCE feature test macro. This prevents compilation with the >>>> musl libc. The patch applies to 2.6.38.2. >>>> >>>> Changes since v1: >>>> - fix scripts/kconfig/lex.zconf.c_shipped >>> this file is autogenerated from zconf.l, which should be updated as >>> well. I'm not sure how you searched for PATH_MAX, but you're still >>> missing `confdata.c' and `nconf.c'. > > Yes, please fix the bison parser and run make GENERATE_PARSER=1 > menuconfig to update the *_shipped files. > > >>> I had a quick look to different libc implementation, glibc and uClibc >>> default to _POSIX_C_SOURCE == 200112L, FreeBSD >8.0 defaults to >>> 200809L for >8.0, FreeBSD 7.x to 200112L. >> >> I got the value I used from the Open Group System Interfaces >> specification, but the musl author said that 200112L would be fine too. > > I suggest you use 200112L, so that it is a nop for glibc/uClibc builds. > Please also accompany it with a /* for PATH_MAX */ comment or so. > no it's not. Defining _POSIX_C_SOURCE disables automatic definition of a few features macros, see below. >> >>> None of these seems to requires _POSIX_C_SOURCE to define PATH_MAX, so >>> I'm not certain of the requirement of the change. >> >> While I don't want to appear like a language lawyer, the specification >> says that 'all symbols required by POSIX.1-2008 to appear when the >> header is included shall be made visible' when an application defines >> _POSIX_C_SOURCE. I guess the musl author interprets that as 'if you >> don't define the feature test macros, you're not getting PATH_MAX.' This >> does not seem to be incorrect behaviour to me. > > While I don't completely understand the motivation for such > super-pedantic libc implementation, the fact is that POSIX says one > should define this macro, so let's define it, it does not hurt us. > If we go that way, we should at least: diff --git a/Makefile b/Makefile index d6592b6..0490413 100644 --- a/Makefile +++ b/Makefile @@ -233,7 +233,7 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \ HOSTCC = gcc HOSTCXX = g++ -HOSTCFLAGS = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer +HOSTCFLAGS = -D_POSIX_C_SOURCE=200112L -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer HOSTCXXFLAGS = -O2 at best: index d6592b6..0490413 100644 --- a/Makefile +++ b/Makefile @@ -233,7 +233,7 @@ CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \ HOSTCC = gcc HOSTCXX = g++ -HOSTCFLAGS = -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer +HOSTCFLAGS = --std=c99 -D_POSIX_C_SOURCE=200112L -Wall -Wmissing-prototypes -Wstrict-prototypes -O2 -fomit-frame-pointer HOSTCXXFLAGS = -O2 Both introduces new warnings with the glibc shipped with fedora 14 relating to strdup(3) needing one of: _SVID_SOURCE, _BSD_SOURCE, _XOPEN_SOURCE, _POSIX_C_SOURCE>=200809L (for __USE_XOPEN2K8). -D_POSIX_C_SOURCE=200809L do not generate more warning, at least on my host. Just for reference, the second change fails anyway as `nconf' uses GNU extension of C99. - Arnaud > Michal > -- > To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in > the body of a message to majordomo@...r.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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