linux-kernel - Re: [patch 2/7] Use extended crashkernel command line on i386

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Message-ID: <20070918043607.GB4842@in.ibm.com>
Date:	Tue, 18 Sep 2007 10:06:07 +0530
From:	Vivek Goyal <vgoyal@...ibm.com>
To:	Bernhard Walle <bwalle@...e.de>
Cc:	kexec@...ts.infradead.org, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [patch 2/7] Use extended crashkernel command line on i386

On Thu, Sep 13, 2007 at 06:14:30PM +0200, Bernhard Walle wrote:
> -
>  void arch_crash_save_vmcoreinfo(void)
>  {
>  #ifdef CONFIG_ARCH_DISCONTIGMEM_ENABLE
> --- a/arch/i386/kernel/setup.c
> +++ b/arch/i386/kernel/setup.c
> @@ -381,6 +381,33 @@ extern unsigned long __init setup_memory
>  extern void zone_sizes_init(void);
>  #endif /* !CONFIG_NEED_MULTIPLE_NODES */
> 
> +#ifdef CONFIG_KEXEC
> +static void reserve_crashkernel(void)
> +{
> +	unsigned long long 	free_mem;
> +	unsigned long long 	crash_size, crash_base;
> +	int			ret;
> +
> +	free_mem = (max_low_pfn + highend_pfn - highstart_pfn) << PAGE_SHIFT;
> +
> +	ret = parse_crashkernel(boot_command_line, free_mem,
> +			&crash_size, &crash_base);
> +	if (ret == 0 && crash_size > 0 && crash_base > 0) {
> +		printk(KERN_INFO "Reserving %ldMB of memory at %ldMB "
> +				"for crashkernel (System RAM: %ldMB)\n",
> +				(unsigned long)(crash_size >> 20),
> +				(unsigned long)(crash_base >> 20),
> +				(unsigned long)(free_mem >> 20));
> +		crashk_res.start = crash_base;
> +		crashk_res.end   = crash_base + crash_size - 1;
> +		reserve_bootmem(crash_base, crash_size);

Hi Bernhard,

I think we might need to do more here. Because [offset] is optional, one
would assume that things will work even if offset is not specified. But
in this patchset, that's not the case for i386 and x86_64. It will silently
fail if a user does not specify the offset. No memory will be reserved for
capture kernel.

I think we either need to make offset mandatory or put in additional
intelligence here to choose the offset automatically based on the memory
available.

Thanks
Vivek
-
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