From: Corinna Vinschen <vinschen@redhat.com>
To: newlib@sourceware.org
Subject: Re: can i delete libtool / shared library support ?
Date: Mon, 7 Feb 2022 12:48:11 +0100 [thread overview]
Message-ID: <YgEG+85nSPUF4meB@calimero.vinschen.de> (raw)
In-Reply-To: <YgDl9AhBMitaTYBd@vapier>
I was never involved in this part of the project, so I can't say
if there's any value in it. Jeff?
On Feb 7 04:27, Mike Frysinger wrote:
> let's talk about the shared library support in newlib. i want to delete it.
>
> it was added in 2001. the commit doesn't have any info itself, and i can't
> find it in the mailing list archives to try and explain "why".
> https://sourceware.org/git/?p=newlib-cygwin.git;a=commit;h=2e1a71756e754ada402efe9f5e2d6378dc11e496
>
> the README has a section on it, but only explains "how", not "why". and that
> leads me to a large limitation in the code: it only works when built for a
> target that already uses glibc, and only 32-bit x86. i.e. it will produce a
> shared libc.so & libm.so, but it doesn't provide its own ld.so, and it will
> still be loaded & run in an environment that otherwise is assuming glibc is
> used. e.g. when you configure gcc, you tell it you're targeting glibc, and
> it bakes assumptions about certain functions & behaviors into it as a result.
>
> i'll note that the configure.host logic is weird in its tuple selection. it
> requires the "vendor" field be set to "pc" even though it's meaningless, and
> it seems to accept any C library (i?86-pc-linux-*), but in reality, it only
> works with glibc (i.e. *-gnu).
>
> back in 2016, Jeff noted that he didn't think anyone used it, and that even
> then the code had rotted into a state that made it unusable (i.e. does not
> compile let alone link). this is because it mixes glibc headers with newlib
> headers, and that glibc had made incompatible changes to its internals. and
> that newlib depends on those internal behaviors.
> https://sourceware.org/legacy-ml/newlib/2016/msg01106.html
>
> i've taken a 32-bit x86 system and tried to compile newlib, and indeed it
> blows up pretty immediately when it starts to mix newlib & glibc headers.
>
> i'm fairly certain that getting it working again won't be that easy since the
> current newlib imported code is based on linuxthreads which was removed from
> glibc 2.4 which was released in 2006, and had already been deprecated for a
> while by that point. the replacement, NPTL, is drastically different.
>
> in my autotools build cleanup, keeping this libtool logic has been kind of a
> pita to try and make sure i don't break it. but on the otherhand, it's been
> broken for at least 5 years (and most likely even longer), no one is using it,
> and it's impossible for me to test. if no one is using it, and no one seems
> to be asking for it, and actually getting it working again will take a huge
> amount of effort, can i just delete all the complicated logic and be done ?
> if someone shows up years from now and wants to get it working, i don't think
> it will be that much harder.
> -mike
next prev parent reply other threads:[~2022-02-07 11:48 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-07 9:27 Mike Frysinger
2022-02-07 10:30 ` Mike Frysinger
2022-02-07 11:48 ` Corinna Vinschen [this message]
2022-02-07 19:30 ` Jeff Johnston
2022-02-08 1:57 ` [PATCH 0/6] delete i?86-pc-linux-gnu & libtool support Mike Frysinger
2022-02-08 1:57 ` [PATCH 1/6] newlib: drop i?86-pc-linux-* target support Mike Frysinger
2022-02-08 1:57 ` [PATCH 2/6] newlib: punt sys/linux support Mike Frysinger
2022-02-08 1:57 ` [PATCH 3/6] newlib: drop unused iconvdata Mike Frysinger
2022-02-08 4:55 ` Joel Sherrill
2022-02-08 1:57 ` [PATCH 4/6] newlib: drop libtool support Mike Frysinger
2022-02-08 9:47 ` Corinna Vinschen
2022-02-09 0:20 ` Mike Frysinger
2022-02-09 10:54 ` Corinna Vinschen
2022-02-09 8:41 ` Brian Inglis
2022-02-09 10:55 ` Corinna Vinschen
2022-02-08 1:57 ` [PATCH 5/6] newlib: drop support for $aext Mike Frysinger
2022-02-08 1:57 ` [PATCH 6/6] newlib: drop support for $oext Mike Frysinger
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