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Message-ID: <4AB51CA2.9010608@kernel.org>
Date: Sat, 19 Sep 2009 11:02:10 -0700
From: Yinghai Lu <yinghai@...nel.org>
To: Ingo Molnar <mingo@...e.hu>
CC: Hugh Dickins <hugh.dickins@...cali.co.uk>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Zachary Amsden <zach@...are.com>,
"H. Peter Anvin" <hpa@...or.com>,
Xiao Guangrong <xiaooguangrong@...fujitsu.com>,
Andrew Morton <akpm@...ux-foundation.org>,
linux-kernel@...r.kernel.org
Subject: Re: linux-next: reservetop fix disables mem=
Ingo Molnar wrote:
> I thoroughly zapped it. Do you know about any commit ID where it snuck
> in?
after close looking, it will break
1. some cpu feature in early stage too, like cpu_has_x2apic
2. will break built-in-command line
3. will break other memmap= and mem=
4. early_dbgp and early_console that will use early_ioremap to access mmio (?)
YH
commit 8126dec32738421afa362114337331337b4be17f
Author: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
Date: Thu Aug 20 20:23:11 2009 +0800
x86: Fix system crash when loading with "reservetop" parameter
The system will die if the kernel is booted with "reservetop"
parameter, in present code, parse "reservetop" parameter after
early_ioremap_init(), and some function still use
early_ioremap() after it.
The problem is, "reservetop" parameter can modify
'FIXADDR_TOP', then the virtual address got by early_ioremap()
is base on old 'FIXADDR_TOP', but the page mapping is base on
new 'FIXADDR_TOP', it will occur page fault, and the IDT is not
prepare yet, so, the system is dead.
So, put parse_early_param() in the front of
early_ioremap_init() in this patch.
Signed-off-by: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
Cc: yinghai@...nel.org
Cc: Andrew Morton <akpm@...ux-foundation.org>
LKML-Reference: <4A8D402F.4080805@...fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@...e.hu>
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 63f32d2..02643cc 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -711,6 +711,11 @@ void __init setup_arch(char **cmdline_p)
printk(KERN_INFO "Command line: %s\n", boot_command_line);
#endif
+ strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
+ *cmdline_p = command_line;
+
+ parse_early_param();
+
/* VMI may relocate the fixmap; do this before touching ioremap area */
vmi_init();
@@ -793,11 +798,6 @@ void __init setup_arch(char **cmdline_p)
#endif
#endif
- strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
- *cmdline_p = command_line;
-
- parse_early_param();
-
#ifdef CONFIG_X86_64
check_efer();
#endif
--
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