Date: Sat, 7 Oct 2017 17:27:42 -0700 From: Mark Millard <markmi@dsl-only.net> To: Mark Linimon <linimon@lonesome.com> Cc: Ian Lepore <ian@freebsd.org>, freebsd-arm <freebsd-arm@freebsd.org> Subject: Re: armv7, building p7zip and -fPIC Message-ID: <29DA467B-BD24-4E1A-B3CC-E1F4BD107DA4@dsl-only.net> In-Reply-To: <20171007214849.GB22150@lonesome.com> References: <CAC67Hz8kctZyTEW%2B0qQRVYLzPEK7cG9JXhw90fwHx84fnuwO0w@mail.gmail.com> <CANCZdfo-1ngKQSkkW5zjZwMWj0QnVnrf2WaJ68=bh_oNPKZ3hw@mail.gmail.com> <CAC67Hz8RxH%2BNd0dPbn4qstpFJEkoFWkKpTQ81sX6K3NUuYPDtA@mail.gmail.com> <1507403387.86205.286.camel@freebsd.org> <20171007214849.GB22150@lonesome.com>
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On 2017-Oct-7, at 2:48 PM, Mark Linimon <linimon@lonesome.com> wrote:
> On Sat, Oct 07, 2017 at 01:09:47PM -0600, Ian Lepore wrote:
>> This is really not just an armv7-only thing, the -fPIC flag should
>> always be used.
>
> OK, I'm going to admit some ignorance and prepare to take my beating.
>
> The last time I tried to pepper some -fPIC flags around without knowing
> what I was doing, I was told (in no uncertain terms) that I didn't know
> what I was doing. While this was true I wasn't happy with the way I was
> told :-)
>
> So can you please provide a "-fPIC for dummies" summary? I'll add it to
> the wiki.
>
> (In my old embedded systems days, we didn't need all this fancy stuff;
> you just stuffed your statically-linked result in the 64KB EPROM and you
> were done.)
Here is my understanding of a recent exchange for
this subject area:
If any architecture needs -fPIC then then
target all of them doing so. In order
of priority:
A) If the original materials have a defined way
to cause -fPIC use that instead of explicitly
using CFLAGS+= -fPIC style.
B) Otherwise use CFLAGS+= -fPIC style.
An example of (A) was audio/liba52 that uses (an
internal?) libtool and had used libtool's
-prefer-non-pic . Such is now removed via:
post-patch:
@${REINPLACE_CMD} '/-prefer-non-pic/d' ${WRKSRC}/configure
instead of separately using CFLAGS+= -fPIC .
(There was the possibility of using -prefer-pic instead.
I'm unsure of the tradeoffs/distinctions vs. what was
done.)
The above wording does not deal with -fpic vs. -fPIC or
possibly other distinctions that might sometimes be
involved.
===
Mark Millard
markmi at dsl-only.net
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