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From: Szabolcs Nagy <nsz@port70.net>
To: Markus Wichmann <nullplan@gmx.net>
Cc: musl@lists.openwall.com, Rui Ueyama <rui314@gmail.com>
Subject: Re: [musl] [PATCH] Explicitly pass the -fno-common flag
Date: Mon, 10 Jan 2022 19:45:27 +0100	[thread overview]
Message-ID: <20220110184527.GD1320090@port70.net> (raw)
In-Reply-To: <20220110165015.GA2046@voyager>

* Markus Wichmann <nullplan@gmx.net> [2022-01-10 17:50:15 +0100]:
> On Sat, Jan 08, 2022 at 08:49:17PM -0500, Rich Felker wrote:
> > The one time bss is significantly preferable to common is for
> > zero-initialized const objects (rare but they might appear in some
> > places) since commons don't actually get made const. I don't think we
> > have any of those that are commons now though.
> >
> 
> Wait, that's a possibility? I thought all constant data would be added
> to .rodata. I thought that was the whole point of .rodata.

const int x;

with -fcommon the x is a common symbol.
(the fact that it was const is lost in the .o)

common symbol is treated as bss at link time,
if there is no actual definition, and thus writable.

with -fno-common x is rodata.

      reply	other threads:[~2022-01-10 18:45 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-01-08  7:45 Rui Ueyama
2022-01-08 23:25 ` Szabolcs Nagy
2022-01-09  1:49   ` Rich Felker
2022-01-10 16:50     ` Markus Wichmann
2022-01-10 18:45       ` Szabolcs Nagy [this message]

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