linux-kernel - Re: 2.6.18-rc3-mm2 early

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Message-ID: <m13bc8b6ca.fsf@ebiederm.dsl.xmission.com>
Date:	Mon, 07 Aug 2006 15:09:57 -0600
From:	ebiederm@...ssion.com (Eric W. Biederman)
To:	Hugh Dickins <hugh@...itas.com>
Cc:	Andrew Morton <akpm@...l.org>,
	Rusty Russell <rusty@...tcorp.com.au>, Andi Kleen <ak@...e.de>,
	linux-kernel@...r.kernel.org
Subject: Re: 2.6.18-rc3-mm2 early_param mem= fix

Hugh Dickins <hugh@...itas.com> writes:

> On Sun, 6 Aug 2006, Hugh Dickins wrote:
>> I was impressed by how fast 2.6.18-rc3-mm2 is under memory pressure,
>> until I noticed that my "mem=512M" boot option was doing nothing.  The
>> two fixes below got it working, but I wonder how many other early_param
>> "option=" args are wrong (e.g. "memmap=" in the same file): x86_64
>> shows many such, i386 shows only one, I've not followed it up further.
>
> Oh, and that's not enough for it to show up in x86_64's /proc/cmdline.

The /proc/cmdline part is easy.

Someone deleted the copy from saved_command_line to command_line.
Since kernel/params.c:parse_args called in init/main.c is destructive
if we don't do this we will never see a reasonable command line in /proc,
and /init implementations that parse /proc/command_line will choke horribly.

Signed-off-by: Eric W. Biederman <ebiederm@...ssion.com>

diff --git a/arch/x86_64/kernel/setup.c b/arch/x86_64/kernel/setup.c
index 3bc1ff4..37206a4 100644
--- a/arch/x86_64/kernel/setup.c
+++ b/arch/x86_64/kernel/setup.c
@@ -378,7 +378,8 @@ #endif
        early_identify_cpu(&boot_cpu_data);
 
        parse_early_param();
-       *cmdline_p = saved_command_line;
+       memcpy(command_line, saved_command_line, COMMAND_LINE_SIZE);
+       *cmdline_p = command_line;
 
        finish_e820_parsing();
 
-
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