From mboxrd@z Thu Jan  1 00:00:00 1970
From: Yasunori Goto <y-goto@jp.fujitsu.com>
Date: Wed, 13 Jul 2005 06:34:48 +0000
Subject: Re: [PATCH] gurantee DMA area for alloc_bootmem_low()
Message-Id: <20050713152030.1B11.Y-GOTO@jp.fujitsu.com>
List-Id: <linux-ia64.vger.kernel.org>
References: <20050712152715.44CD.Y-GOTO@jp.fujitsu.com> <20050712183021.GC3987@w-mikek2.ibm.com>
In-Reply-To: <20050712183021.GC3987@w-mikek2.ibm.com>
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To: Mike Kravetz <kravetz@us.ibm.com>
Cc: linux-mm <linux-mm@kvack.org>, "Luck, Tony" <tony.luck@intel.com>, linux-ia64@vger.kernel.org, "Martin J. Bligh" <mbligh@mbligh.org>

> On Tue, Jul 12, 2005 at 03:50:09PM +0900, Yasunori Goto wrote:
> > Index: allocbootmem/mm/bootmem.c
> > =================================> > --- allocbootmem.orig/mm/bootmem.c	2005-06-30 11:57:13.000000000 +0900
> > +++ allocbootmem/mm/bootmem.c	2005-07-08 20:46:56.209040741 +0900
> > @@ -387,10 +387,16 @@
> >  	pg_data_t *pgdat = pgdat_list;
> >  	void *ptr;
> >  
> > -	for_each_pgdat(pgdat)
> > +	for_each_pgdat(pgdat){
> > +
> > +		if (goal < __pa(MAX_DMA_ADDRESS) &&
> > +		    pgdat->bdata->node_boot_start >= __pa(MAX_DMA_ADDRESS))
> > +			continue; /* Skip No DMA node */
> > +
> >  		if ((ptr = __alloc_bootmem_core(pgdat->bdata, size,
> >  						align, goal)))
> >  			return(ptr);
> > +	}
> >  
> >  	/*
> >  	 * Whoops, we cannot satisfy the allocation request.
> 
> Need to be careful about the use of MAX_DMA_ADDRESS.  It is not always
> the case that archs define MAX_DMA_ADDRESS as a real address.  In some
> cases, MAX_DMA_ADDRESS is defined as something like -1 to indicate that
> all addresses are available for DMA.  I'm not sure that the above code
> will always work as desired in such cases.

Hmm... Thanks for your advise.

If MAX_DMA_ADDRESS is like -1, then all of memory can be DMA'ble, 
right?  How is like this? One more comparison is added.

	if (MAX_DMA_ADDRESS != ~0UL  &&
		goal < __pa(MAX_DMA_ADDRESS) &&
		pgdat->bdata->node_boot_start >= 
		__pa(MAX_DMA_ADDRESS))

Thanks.

-- 
Yasunori Goto