linux-kernel - Re: 2.6.23-rc4-mm1 build issue: ia64 link error

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Message-ID: <a781481a0709080050g746718a7y3c808c2d4f3c4e73@mail.gmail.com>
Date:	Sat, 8 Sep 2007 13:20:55 +0530
From:	"Satyam Sharma" <satyam.sharma@...il.com>
To:	"Andrew Morton" <akpm@...ux-foundation.org>
Cc:	"Luck, Tony" <tony.luck@...el.com>, mathieu.desnoyers@...ymtl.ca,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.23-rc4-mm1 build issue: ia64 link error

On 9/8/07, Satyam Sharma <satyam.sharma@...il.com> wrote:
> On 9/7/07, Andrew Morton <akpm@...ux-foundation.org> wrote:
> > > On Fri, 7 Sep 2007 00:34:59 -0700 "Luck, Tony" <tony.luck@...el.com> wrote:
> > > > local symbol 0: discarded in section `.exit.text' from arch/ia64/kernel/built-in.o
> > >
> > > This usually means that there is a static __exit function (or __devexit etc.)
> > > somewhere in the object being linked.  The error message is pretty unhelpful
> > > in figuring out *where* in the module.  Look at the 'mm' patches that touch
> > > arch/ia64/kernel to see if one of them tinkers with __exit* attributes.
> >
> > Confused.  There are >2500 static __exit functions in the tree, including
> > ones like
> >
> > arch/ia64/kernel/esi.c:static void __exit esi_exit (void)
>
> That message means the linker found someone referencing an .exit.text
> function -- on other archs this would've been a section mismatch but on
> ia64 its a link error due to reasons below
> (although it would not have ever caused an oops).
  ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

In general, there's obviously nothing wrong with ia64's policy of discarding
.exit.text at link time (in fact it's a good optimization), and generally most
references from .init.text (or .text) to .exit.text would really be oopsen.

But not so with this case, because with HOTPLUG_CPU=n (which is when
this link error can occur) it's not possible for the notifier to be
called out in
the first place, and especially not for a CPU_DEAD event, which is when
this reference could've occurred in practice.

Anyway, I came across another little thing while investigating this, patch
attached ...


Satyam

View attachment "ia64-perfmon-remove-exit_pfm_fs.patch" of type "text/x-diff" (715 bytes)