[PATCH] kexec: x86: struct x86_linux_param_header should be packed

From: Vivek Goyal <vgoyal@redhat.com>
To: Kexec Mailing List <kexec@lists.infradead.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH] kexec: x86: struct x86_linux_param_header should be packed
Date: Mon, 5 Aug 2013 13:35:11 -0400	[thread overview]
Message-ID: <20130805173510.GD2274@redhat.com> (raw)

I think struct x86_linux_param_header should be packed. Strange that we
did not do it so far. 

Without packing struct size was 3824 (decimal) on my x86_64 machine. With
packing it is 3820. I think there was a padding of 4 bytes at the end. So
it should be harmless.

I tried to introduce more fields and that introduced padding in the
middle of structure and kexec stopped working and that's how I got to
know that bootparam is not packed.

Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
---
 include/x86/x86-linux.h |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: kexec-tools/include/x86/x86-linux.h
===================================================================

--- kexec-tools.orig/include/x86/x86-linux.h	2013-08-05 13:28:33.999338740 -0400
+++ kexec-tools/include/x86/x86-linux.h	2013-08-05 13:28:46.616475104 -0400
@@ -198,7 +198,7 @@ struct x86_linux_param_header {
 	struct 	edd_info eddbuf[EDDMAXNR];	/* 0xd00 */
 						/* 0xeec */
 #define COMMAND_LINE_SIZE 2048
-};
+} __attribute__ ((packed));
 
 struct x86_linux_faked_param_header {
 	struct x86_linux_param_header hdr;	/* 0x00 */

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