Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760882AbZCMRFy (ORCPT ); Fri, 13 Mar 2009 13:05:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759773AbZCMRBW (ORCPT ); Fri, 13 Mar 2009 13:01:22 -0400 Received: from gw.goop.org ([64.81.55.164]:57402 "EHLO abulafia.goop.org" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1759748AbZCMRBV (ORCPT ); Fri, 13 Mar 2009 13:01:21 -0400 From: Jeremy Fitzhardinge To: "H. Peter Anvin" Cc: the arch/x86 maintainers , Linux Kernel Mailing List , Xen-devel , David Airlie , Jeremy Fitzhardinge Subject: [PATCH 17/27] xen/swiotlb: improve comment on gfp flags in xen_alloc_coherent() Date: Fri, 13 Mar 2009 10:00:02 -0700 Message-Id: <1236963612-14287-18-git-send-email-jeremy@goop.org> X-Mailer: git-send-email 1.6.0.6 In-Reply-To: <1236963612-14287-1-git-send-email-jeremy@goop.org> References: <1236963612-14287-1-git-send-email-jeremy@goop.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1415 Lines: 44 From: Jeremy Fitzhardinge Clarify why we don't care about the kernel's pseudo-phys restrictions, so long as the underlying pages are in the right place. Signed-off-by: Jeremy Fitzhardinge --- drivers/pci/xen-iommu.c | 10 ++++++---- 1 files changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/pci/xen-iommu.c b/drivers/pci/xen-iommu.c index 7b6fd3e..13cfe0c 100644 --- a/drivers/pci/xen-iommu.c +++ b/drivers/pci/xen-iommu.c @@ -202,15 +202,17 @@ static void *xen_alloc_coherent(struct device *dev, size_t size, unsigned long vstart; u64 mask; - /* ignore region specifiers */ + /* + * Ignore region specifiers - the kernel's ideas of + * pseudo-phys memory layout has nothing to do with the + * machine physical layout. We can't allocate highmem + * because we can't return a pointer to it. + */ gfp &= ~(__GFP_DMA | __GFP_HIGHMEM); if (dma_alloc_from_coherent(dev, size, dma_handle, &ret)) return ret; - if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff)) - gfp |= GFP_DMA; - vstart = __get_free_pages(gfp, order); ret = (void *)vstart; -- 1.6.0.6 -- 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/