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From: Andrew Morton <akpm@linux-foundation.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: linux-kernel@vger.kernel.org, Rik van Riel <riel@surriel.com>,
	Mike Galbraith <efault@gmx.de>,
	Dave Hansen <dave.hansen@intel.com>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: Build failures with gcc 4.5 and older
Date: Tue, 14 Aug 2018 14:36:55 -0700	[thread overview]
Message-ID: <20180814143655.3acd4bb211d44747f77e74f2@linux-foundation.org> (raw)
In-Reply-To: <20180814170904.GA12768@roeck-us.net>

On Tue, 14 Aug 2018 10:09:04 -0700 Guenter Roeck <linux@roeck-us.net> wrote:

> Since commit c1a2f7f0c0645 ("mm: Allocate the mm_cpumask
> (mm->cpu_bitmap[]) dynamically based on nr_cpu_ids"), building
> the Linux kernel with gcc version 4.5 and older fails as follows.
> 
> In file included from ./include/linux/mm.h:17:0,
>                  from ./include/linux/pid_namespace.h:7,
> 		 from ./include/linux/ptrace.h:10,
> 		 from arch/openrisc/kernel/asm-offsets.c:32:
> ./include/linux/mm_types.h:497:16: error: flexible array member in otherwise empty struct

Confused.  Why does it think that the mm_struct is "otherwise empty"?

This shuts it up:

--- a/include/linux/mm_types.h~a
+++ a/include/linux/mm_types.h
@@ -490,6 +490,7 @@ struct mm_struct {
 #endif
 	} __randomize_layout;
 
+	int wibble;
 	/*
 	 * The mm_cpumask needs to be at the end of mm_struct, because it
 	 * is dynamically sized based on nr_cpu_ids.


So we could add something like that, along with the appropriate #if
GCC_VERSION and a comment.  A simple enough change, to keep those old
gcc versions limping along for a bit longer?


  parent reply	other threads:[~2018-08-14 21:37 UTC|newest]

Thread overview: 24+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-14 17:09 Build failures with gcc 4.5 and older Guenter Roeck
2018-08-14 17:20 ` Linus Torvalds
2018-08-14 17:36   ` Guenter Roeck
2018-08-14 20:19     ` Tony Luck
2018-08-15 16:09       ` Tony Luck
2018-08-15 16:34         ` Linus Torvalds
2018-08-16  0:27           ` Guenter Roeck
2018-08-15 16:49         ` Guenter Roeck
2018-08-14 17:48 ` Joe Perches
2018-08-19 21:23   ` Kees Cook
2018-08-20 17:46   ` Nick Desaulniers
2018-08-20 18:34     ` Linus Torvalds
2018-08-14 21:36 ` Andrew Morton [this message]
2018-08-14 22:15   ` Guenter Roeck
2018-08-14 23:02     ` Andrew Morton
2018-08-14 23:20       ` Linus Torvalds
2018-08-15  1:02         ` Guenter Roeck
2018-08-20 14:53           ` Thomas Gleixner
2018-08-20 16:00             ` Arnd Bergmann
2018-08-15 12:40 ` David Laight
2018-08-15 15:44   ` Linus Torvalds
2018-08-15 16:18     ` David Laight
2018-08-15 16:33       ` Linus Torvalds
2018-08-16  9:17         ` David Laight

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