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Re: [PATCH v2] mips: delete __cpuinit/__CPUINIT usage from MIPS code

To: Paul Gortmaker <paul.gortmaker@windriver.com>, Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH v2] mips: delete __cpuinit/__CPUINIT usage from MIPS code
From: David Daney <ddaney.cavm@gmail.com>
Date: Wed, 19 Jun 2013 15:19:33 -0700
Cc: linux-mips@linux-mips.org
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On 06/18/2013 07:38 AM, Paul Gortmaker wrote:
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
and are flagged as __cpuinit  -- so if we remove the __cpuinit from
the arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
related content into no-ops as early as possible, since that will get
rid of these warnings.  In any case, they are temporary and harmless.

Here, we remove all the MIPS __cpuinit from C code and __CPUINIT
from asm files.  MIPS is interesting in this respect, because there
are also uasm users hiding behind their own renamed versions of the
__cpuinit macros.

[1] https://lkml.org/lkml/2013/5/20/589

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

I get:


WARNING: vmlinux.o(.text+0x18640): Section mismatch in reference from the function register_cavium_notifier() to the variable .cpuinit.data:octeon_cpu_callback_nb.37045
The function register_cavium_notifier() references
the variable __cpuinitdata octeon_cpu_callback_nb.37045.
This is often because register_cavium_notifier lacks a __cpuinitdata
annotation or the annotation of octeon_cpu_callback_nb.37045 is wrong.

WARNING: vmlinux.o(.text+0x18650): Section mismatch in reference from the function register_cavium_notifier() to the variable .cpuinit.data:octeon_cpu_callback_nb.37045
The function register_cavium_notifier() references
the variable __cpuinitdata octeon_cpu_callback_nb.37045.
This is often because register_cavium_notifier lacks a __cpuinitdata
annotation or the annotation of octeon_cpu_callback_nb.37045 is wrong.

WARNING: vmlinux.o(.text+0x24778): Section mismatch in reference from the function start_secondary() to the function .cpuinit.text:calibrate_delay()
The function start_secondary() references
the function __cpuinit calibrate_delay().
This is often because start_secondary lacks a __cpuinit
annotation or the annotation of calibrate_delay is wrong.

WARNING: vmlinux.o(.text+0x247b4): Section mismatch in reference from the function start_secondary() to the function .cpuinit.text:notify_cpu_starting()
The function start_secondary() references
the function __cpuinit notify_cpu_starting().
This is often because start_secondary lacks a __cpuinit
annotation or the annotation of notify_cpu_starting is wrong.



So I think an alternate approach is required.

Really I think we need to leave all existing __cpuinitdata and __cpuinit annotations in place.

Instead we would first change the definitions of these two to be empyt:

#define __cpuinit
#define __cpuinitdata

Once that is working, we would make a second pass and remove the symbols themselves.

David Daney

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