linux-kernel - Re: linux-next: reservetop fix disables mem=

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Date:	Sat, 5 Sep 2009 23:56:18 -0700
From:	Yinghai Lu <yhlu.kernel@...il.com>
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=

On Mon, Aug 24, 2009 at 11:27 AM, Ingo Molnar<mingo@...e.hu> wrote:
>
> * Yinghai Lu <yinghai@...nel.org> wrote:
>
>> Hugh Dickins wrote:
>> > I find the "mem=" boot parameter disabled in today's linux-next:
>> > reverting the tip commit below fixes that.
>> >
>> > Hugh
>> >
>> > From: Xiao Guangrong <xiaoguangrong@...fujitsu.com>
>> > Date: Thu, 20 Aug 2009 12:23:11 +0000 (+0800)
>> > Subject: x86: Fix system crash when loading with "reservetop" parameter
>> > X-Git-Url: http://git.kernel.org/?p=linux%2Fkernel%2Fgit%2Fmingo%2Flinux-2.6-x86.git;a=commitdiff_plain;h=8126dec32738421afa362114337331337b4be17f
>> >
>> > 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
>>
>> yes, that patch will break other built-in command too.
>>
>> need drop that patch.
>
> done. Was nervous about the patch already:
>
>  http://lkml.org/lkml/2009/8/21/127
>
>> also the problem was caused by vmi patch, and that commit should
>> be reverted.
>>
>> commit ae8d04e2ecbb233926860e9ce145eac19c7835dc
>> Author: Zachary Amsden <zach@...are.com>
>> Date:   Sat Dec 13 12:36:58 2008 -0800
>>
>>     x86 Fix VMI crash on boot in 2.6.28-rc8
>>
>>     VMI initialiation can relocate the fixmap, causing early_ioremap to
>>     malfunction if it is initialized before the relocation.  To fix this,
>>     VMI activation is split into two phases; the detection, which must
>>     happen before setting up ioremap, and the activation, which must happen
>>     after parsing early boot parameters.
>>
>>     This fixes a crash on boot when VMI is enabled under VMware.
>>
>>     Signed-off-by: Zachary Amsden <zach@...are.com>
>>     Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
>>
>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
>> index 9d5674f..bdec76e 100644
>> --- a/arch/x86/kernel/setup.c
>> +++ b/arch/x86/kernel/setup.c
>> @@ -794,6 +794,9 @@ void __init setup_arch(char **cmdline_p)
>>         printk(KERN_INFO "Command line: %s\n", boot_command_line);
>>  #endif
>>
>> +       /* VMI may relocate the fixmap; do this before touching ioremap area */
>> +       vmi_init();
>> +
>>         early_cpu_init();
>>         early_ioremap_init();
>>
>> @@ -880,13 +883,8 @@ void __init setup_arch(char **cmdline_p)
>>         check_efer();
>>  #endif
>>
>> -#if defined(CONFIG_VMI) && defined(CONFIG_X86_32)
>> -       /*
>> -        * Must be before kernel pagetables are setup
>> -        * or fixmap area is touched.
>> -        */
>> -       vmi_init();
>> -#endif
>> +       /* Must be before kernel pagetables are setup */
>> +       vmi_activate();
>>
>>         /* after early param, so could get panic from serial */
>>         reserve_early_setup_data();
>>
>>
>> and according to
>> http://lkml.org/lkml/2008/12/10/388
>> http://lkml.org/lkml/2008/12/10/456
>>
>> Zachary should split reserve_top_address() to two functions...
>> before sending that patch to Linus
>
> mind looking at this yourself if interested? Zachary has not been
> active for quite some time.
>

please check attached patch...

still need to make early_dbgp and early_console that would use early_ioremap?

YH

View attachment "fix_early_param.patch" of type "text/x-patch" (6200 bytes)