linux-kernel - [PATCH 2/11] i386: Remove unnecessary ALIGN() in vmlinux.lds.S

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Message-ID: <20061023192923.GC13263@in.ibm.com>
Date:	Mon, 23 Oct 2006 15:29:23 -0400
From:	Vivek Goyal <vgoyal@...ibm.com>
To:	linux kernel mailing list <linux-kernel@...r.kernel.org>
Cc:	Reloc Kernel List <fastboot@...ts.osdl.org>, ebiederm@...ssion.com,
	akpm@...l.org, ak@...e.de, hpa@...or.com, magnus.damm@...il.com,
	lwang@...hat.com, dzickus@...hat.com, maneesh@...ibm.com
Subject: [PATCH 2/11] i386: Remove unnecessary ALIGN() in vmlinux.lds.S



o There seems to be one extra ALIGN(4096) before symbol __smp_alt_end. The
  only usage of __smp_alt_end is to mark the end of smp alternative
  sections so that this memory can be freed. As a physical page is freed
  one has to just make sure that there is no other data on the same page
  where __smp_alt_end is pointing. There is already a ALIGN(4096) after
  this section which should take care of the above issue. Hence it looks
  like the ALIGN(4096) before __smp_alt_end is redundant and not required.

Signed-off-by: Vivek Goyal <vgoyal@...ibm.com>
---

 arch/i386/kernel/vmlinux.lds.S |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff -puN arch/i386/kernel/vmlinux.lds.S~i386-remove-unnecessary-align-option arch/i386/kernel/vmlinux.lds.S
--- linux-2.6.19-rc2-git7-reloc/arch/i386/kernel/vmlinux.lds.S~i386-remove-unnecessary-align-option	2006-10-23 13:15:21.000000000 -0400
+++ linux-2.6.19-rc2-git7-reloc-root/arch/i386/kernel/vmlinux.lds.S	2006-10-23 15:09:02.000000000 -0400
@@ -112,11 +112,15 @@ SECTIONS
   }
   .smp_altinstr_replacement : AT(ADDR(.smp_altinstr_replacement) - LOAD_OFFSET) {
 	*(.smp_altinstr_replacement)
-	. = ALIGN(4096);
 	__smp_alt_end = .;
   }
 
-  /* will be freed after init */
+  /* will be freed after init
+   * Following ALIGN() is required to make sure no other data falls on the
+   * same page where __smp_alt_end is pointing as that page might be freed
+   * after boot. Always make sure that ALIGN() directive is present after
+   * the section which contains __smp_alt_end.
+   */
   . = ALIGN(4096);		/* Init code and data */
   .init.text : AT(ADDR(.init.text) - LOAD_OFFSET) {
   	__init_begin = .;
_
-
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