From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx173.postini.com [74.125.245.173]) by kanga.kvack.org (Postfix) with SMTP id 744D06B0119 for ; Wed, 12 Sep 2012 20:34:07 -0400 (EDT) Received: by dadi14 with SMTP id i14so1535646dad.14 for ; Wed, 12 Sep 2012 17:34:06 -0700 (PDT) Date: Wed, 12 Sep 2012 17:34:00 -0700 From: Tejun Heo Subject: Re: [PATCH] mm: bootmem: use phys_addr_t for physical addresses Message-ID: <20120913003400.GA25889@localhost> References: <1347466008-7231-1-git-send-email-cyril@ti.com> <20120912203920.GU7677@google.com> <505123FE.2090305@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <505123FE.2090305@ti.com> Sender: owner-linux-mm@kvack.org List-ID: To: Cyril Chemparathy Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, akpm@linux-foundation.org, davem@davemloft.net, eric.dumazet@gmail.com, hannes@cmpxchg.org, shangw@linux.vnet.ibm.com, vitalya@ti.com Hello, On Wed, Sep 12, 2012 at 08:08:30PM -0400, Cyril Chemparathy wrote: > >So, a function which takes phys_addr_t for goal and limit but returns > >void * doesn't make much sense unless the function creates directly > >addressable mapping somewhere. > > On the 32-bit PAE platform in question, physical memory is located > outside the 4GB range. Therefore phys_to_virt takes a 64-bit > physical address and returns a 32-bit kernel mapped lowmem pointer. Yes but phys_to_virt() can return the vaddr only if the physical address is already mapped in the kernel address space; otherwise, you need one of the kmap*() calls which may not be online early in the boot and consumes either the vmalloc area or fixmaps. bootmem interface can't handle unmapped memory. Thanks. -- tejun -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org