From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756472AbWKSGPX (ORCPT ); Sun, 19 Nov 2006 01:15:23 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756473AbWKSGPX (ORCPT ); Sun, 19 Nov 2006 01:15:23 -0500 Received: from mtiwmhc11.worldnet.att.net ([204.127.131.115]:14820 "EHLO mtiwmhc11.worldnet.att.net") by vger.kernel.org with ESMTP id S1756471AbWKSGPW (ORCPT ); Sun, 19 Nov 2006 01:15:22 -0500 Message-ID: <455FF672.4070502@lwfinger.net> Date: Sun, 19 Nov 2006 00:15:14 -0600 From: Larry Finger User-Agent: Thunderbird 1.5.0.8 (X11/20061025) MIME-Version: 1.0 To: LKML CC: Ray Lee Subject: Problem with DMA on x86_64 with 3 GB RAM References: <455B63EC.8070704@madrabbit.org> <20061118112438.GB15349@nineveh.rivenstone.net> <1163868955.27188.2.camel@johannes.berg> <455F3D44.4010502@lwfinger.net> <455F4271.1060405@madrabbit.org> In-Reply-To: <455F4271.1060405@madrabbit.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org I am trying to debug a bcm43xx DMA problem on an x86_64 system with 3 GB RAM. Depending on the particular chip and its implementation, dma transfers may use 64-, 32-, or 30-bit addressing, with the problem interface using 30-bit addressing. From test prints, the correct mask (0x3FFFFFFF) is supplied to pci_set_dma_mask and pci_set_consistent_dma_mask. Neither call returns an error. In addition, several x86_64 systems with more than 1 GB RAM have worked with the current code. If the system is booted with mem=1024M on the command line, it operates normally; however, it gets a kernel NULL pointer dereference and panics when booted with either 2 or 3 GB RAM. The config parameters in the processor section are as follows: CONFIG_X86_64=y CONFIG_64BIT=y CONFIG_X86=y CONFIG_ZONE_DMA32=y CONFIG_LOCKDEP_SUPPORT=y CONFIG_STACKTRACE_SUPPORT=y CONFIG_SEMAPHORE_SLEEPERS=y CONFIG_MMU=y CONFIG_RWSEM_GENERIC_SPINLOCK=y CONFIG_GENERIC_HWEIGHT=y CONFIG_GENERIC_CALIBRATE_DELAY=y CONFIG_X86_CMPXCHG=y CONFIG_EARLY_PRINTK=y CONFIG_GENERIC_ISA_DMA=y CONFIG_GENERIC_IOMAP=y CONFIG_ARCH_MAY_HAVE_PC_FDC=y CONFIG_ARCH_POPULATES_NODE_MAP=y CONFIG_DMI=y CONFIG_AUDIT_ARCH=y CONFIG_DEFCONFIG_LIST="/lib/modules/$UNAME_RELEASE/.config" I would appreciate any tips on debugging this problem. Are there any quantities that should be dumped, etc? Thanks, Larry