linux-kernel - Re: [PATCH] x86: let 'reservetop' functioning right

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Date:	Wed, 31 Mar 2010 10:49:44 +0800
From:	Liang Li <liang.li@...driver.com>
To:	mingo@...e.hu
Cc:	linux-kernel@...r.kernel.org, wangchen@...fujitsu.com,
	akpm@...ux-foundation.org
Subject: Re: [PATCH] x86: let 'reservetop' functioning right

Hi Ingo,

Seems the problem still there in 2.6.34-rc3. When pass
'reservetop=0x1000' to x86_32 kernel, kernel hangs on
very early boot stage.

Do we have any plan to abandon 'reservetop' or due to
some reason that the patch is non-acceptable?

Thanks,
		-Liang Li

On Thu, Mar 25, 2010 at 08:54:05AM +0800, Liang Li wrote:
> When specify 'reservetop=0xabc000' kernel parameter, kernel will hang
> on boot due to a early_ioremap bug that relate to commit 8827247ff.
> 
> The root cause of boot failure problem is the value of 'slot_virt[i]'
> was initialized in setup_arch->early_ioremap_init. But later in
> setup_arch, the function 'parse_early_param' will modify 'FIXADDR_TOP'
> when 'reservetop=0xbadc0de' being specified.
> 
> The simplest fix might be use __fix_to_virt(idx0) to get updated value
> of 'FIXADDR_TOP' in '__early_ioremap' instead of reference old value
> from slot_virt[slot] directly.
> 
> Signed-off-by: Liang Li <liang.li@...driver.com>
> ---
>  arch/x86/mm/ioremap.c |    4 ++--
>  1 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/mm/ioremap.c b/arch/x86/mm/ioremap.c
> index 5eb1ba7..ea82ef0 100644
> --- a/arch/x86/mm/ioremap.c
> +++ b/arch/x86/mm/ioremap.c
> @@ -537,9 +537,9 @@ __early_ioremap(resource_size_t phys_addr, unsigned long size, pgprot_t prot)
>  		--nrpages;
>  	}
>  	if (early_ioremap_debug)
> -		printk(KERN_CONT "%08lx + %08lx\n", offset, slot_virt[slot]);
> +		printk(KERN_CONT "%08lx + %08lx\n", offset, __fix_to_virt(idx0));
>  
> -	prev_map[slot] = (void __iomem *)(offset + slot_virt[slot]);
> +	prev_map[slot] = (void __iomem *)(offset + __fix_to_virt(idx0));
>  	return prev_map[slot];
>  }
>  
> -- 
> 1.6.6
> 
> --
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