Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756594Ab0FNVRe (ORCPT ); Mon, 14 Jun 2010 17:17:34 -0400 Received: from g1t0029.austin.hp.com ([15.216.28.36]:48290 "EHLO g1t0029.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756468Ab0FNVRd convert rfc822-to-8bit (ORCPT ); Mon, 14 Jun 2010 17:17:33 -0400 From: "Altobelli, David" To: Andrew Morton , Prarit Bhargava CC: "linux-kernel@vger.kernel.org" , "stable@kernel.org" , "Camuso, Tony" , "dzickus@redhat.com" Date: Mon, 14 Jun 2010 21:16:34 +0000 Subject: RE: [PATCH]: hpilo: fix pointer warning in ilo_ccb_setup [v2] Thread-Topic: [PATCH]: hpilo: fix pointer warning in ilo_ccb_setup [v2] Thread-Index: AcsL91Se1nwD0XcDS2++Qt24hntw1AAClIGg Message-ID: <92D64232F2316045B18937D5C9996B152CD7EDAE9F@GVW1144EXB.americas.hpqcorp.net> References: <20100608151923.10554.57721.sendpatchset@prarit.bos.redhat.com> <20100614122517.775fc67c.akpm@linux-foundation.org> In-Reply-To: <20100614122517.775fc67c.akpm@linux-foundation.org> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: en-US Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 8BIT MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1115 Lines: 20 > From Andrew Morton: > So what's happening here. As send_fifobar_pa, send_desc_pa, > recv_fifobar_pa and recv_desc_pa are only ever written to, I assume > that we're writing a 64-bit value and then reading it back via the > 32-bit value which shares the same storage. The physical addresses are used to fill out a structure defined by iLO firmware that has 64 bit fields for the various queues or descriptors. A copy with physical addrs is copied to device memory. The size of the structure matters for the physical copy, which is why those fields need to be u64, not a variable type like dma_addr_t, or a pointer. We keep a copy with virtual addresses for use by the kernel. The size of the kernel pointer doesn't really matter, it just tells the driver where to write in the shared memory. Does that answer your question, maybe I missed what concerned you? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/