linux-kernel - Re: [RESEND][PATCH v2 2/2] powerpc/fadump: parse fadump reserve memory size based on memory range

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Date:	Thu, 04 Aug 2016 19:45:28 +1000
From:	Michael Ellerman <mpe@...erman.id.au>
To:	Hari Bathini <hbathini@...ux.vnet.ibm.com>, rusty@...tcorp.com.au,
	ebiederm@...ssion.com, vgoyal@...hat.com,
	linuxppc-dev <linuxppc-dev@...abs.org>
Cc:	Mahesh J Salgaonkar <mahesh@...ux.vnet.ibm.com>,
	kexec@...ts.infradead.org, lkml <linux-kernel@...r.kernel.org>,
	Ananth N Mavinakayanahalli <ananth@...ibm.com>
Subject: Re: [RESEND][PATCH v2 2/2] powerpc/fadump: parse fadump reserve memory size based on memory range

Hari Bathini <hbathini@...ux.vnet.ibm.com> writes:
...
>  /**
>   * fadump_calculate_reserve_size(): reserve variable boot area 5% of System RAM
>   *
> @@ -212,12 +262,17 @@ static inline unsigned long fadump_calculate_reserve_size(void)
>  {
>  	unsigned long size;
>  
> +	/* sets fw_dump.reserve_bootvar */
> +	parse_fadump_reserve_mem();
> +
>  	/*
>  	 * Check if the size is specified through fadump_reserve_mem= cmdline
>  	 * option. If yes, then use that.
>  	 */
>  	if (fw_dump.reserve_bootvar)
>  		return fw_dump.reserve_bootvar;
> +	else
> +		printk(KERN_INFO "fadump: calculating default boot size\n");
>  
>  	/* divide by 20 to get 5% of value */
>  	size = memblock_end_of_DRAM() / 20;

The code already knows how to reserve 5% based on the size of the machine's
memory, as long as no commandline parameter is passed. So why can't we
just use that logic?

cheers