Date: Wed, 4 May 2022 13:22:57 -0700 From: John Baldwin <jhb@FreeBSD.org> To: sgk@troutmask.apl.washington.edu Cc: Ed Maste <emaste@freebsd.org>, FreeBSD Current <freebsd-current@freebsd.org> Subject: Re: Profiled libraries on freebsd-current Message-ID: <4b128639-f233-acfe-aeb4-5830aa973cb6@FreeBSD.org> In-Reply-To: <YnLZraesrXQJdgy3@troutmask.apl.washington.edu> References: <Ymt%2BICLaQPxx2knx@troutmask.apl.washington.edu> <CAPyFy2CuSFd7zm8BvrWYDv%2BEgM0Ryz-bxwWNzUEMEkm0fruokA@mail.gmail.com> <Ym1XE9QSSvIy/4uo@troutmask.apl.washington.edu> <CAPyFy2AcKcT3NmpA5cs0WG4B7gPCJwdax%2BPp02YHEQBmJ10ZtQ@mail.gmail.com> <Ym6tJn60RmqQVsrv@troutmask.apl.washington.edu> <CAPyFy2DJp6ycnqsZMH%2B094B%2BhykYrF4T5PN3qHm9qogVkQm9dQ@mail.gmail.com> <YnAWvEvQaNgzTFYn@troutmask.apl.washington.edu> <80e38cf3-0d53-fce6-76e6-936c47d95c91@FreeBSD.org> <YnLZraesrXQJdgy3@troutmask.apl.washington.edu>
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On 5/4/22 12:53 PM, Steve Kargl wrote: > On Wed, May 04, 2022 at 11:12:55AM -0700, John Baldwin wrote: >> On 5/2/22 10:37 AM, Steve Kargl wrote: >>> On Mon, May 02, 2022 at 12:32:25PM -0400, Ed Maste wrote: >>>> On Sun, 1 May 2022 at 11:54, Steve Kargl >>>> <sgk@troutmask.apl.washington.edu> wrote: >>>>> >>>>> diff --git a/gcc/config/freebsd-spec.h b/gcc/config/freebsd-spec.h >>>>> index 594487829b5..1e8ab2e1827 100644 >>>>> --- a/gcc/config/freebsd-spec.h >>>>> +++ b/gcc/config/freebsd-spec.h >>>>> @@ -93,14 +93,22 @@ see the files COPYING3 and COPYING.RUNTIME respectively. If not, see >>>>> (similar to the default, except no -lg, and no -p). */ >>>>> >>>>> #ifdef FBSD_NO_THREADS >>>> >>>> I wonder if we can simplify things now, and remove this >>>> `FBSD_NO_THREADS` case. I didn't see anything similar in other GCC >>>> targets I looked at. >>> >>> That I don't know. FBSD_NO_THREADS is defined in freebsd-nthr.h. >>> In fact, it's the only thing in that header (except copyright >>> broilerplate). freebsd-nthr.h only appears in config.gcc and >>> seems to only get added to the build if someone runs configure >>> with --enable-threads=no. Looking at my last config.log for >>> gcc trunk, I see "Thread model: posix", which appears to be >>> the default case or if someone does --enable-threads=yes or >>> --enable-threads=posix. So, I suppose it comes down to >>> two questions: (1) is libpthread.* available on all supported >>> targets and versions? (2) does anyone build gcc without >>> threads support? >> >> libpthread is available on all supported architectures on all >> supported versions. libthr has been the default threading library >> since 7.0 and the only supported library since 8.0. In GDB I just >> assume libthr style threads, and I think GCC can safely do the >> same. >> > > I don't know the entire FreeBSD ecosystem. Do people > use FreeBSD on embedded systems (e.g., nanobsd) where > libthr may be stripped out? Thus, --enable-threads=no > is needed. If they do, they are also using a constrained userland and probably are not shipping a GCC binary either. However, it's not clear to me what --enable-threads means. Does this enable -pthread as an option? If so, that should definitely just always be on. It's still an option users have to opt into via a command line flag and doesn't prevent building non-threaded programs. If it's enabling use of threads at runtime within GCC itself, I'd say that also should probably just be allowed to be on. I can't really imagine what else it might mean (and I doubt it means the latter). -- John Baldwin
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