From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Young Subject: Re: [PATCH v11 02/10] iommu/vt-d: Items required for kdump Date: Wed, 13 May 2015 16:42:26 +0800 Message-ID: <20150513084226.GO4561@localhost.localdomain> References: <1431337974-545-1-git-send-email-zhen-hual@hp.com> <1431337974-545-3-git-send-email-zhen-hual@hp.com> <20150512081723.GC4561@localhost.localdomain> <5552ACB9.5050309@hp.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Content-Disposition: inline In-Reply-To: <5552ACB9.5050309-VXdhtT5mjnY@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: iommu-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Li, ZhenHua" Cc: bhe-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, tom.vaden-VXdhtT5mjnY@public.gmane.org, rwright-VXdhtT5mjnY@public.gmane.org, linux-pci-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kexec-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, lisa.mitchell-VXdhtT5mjnY@public.gmane.org, iommu-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, doug.hatch-VXdhtT5mjnY@public.gmane.org, ishii.hironobu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, bhelgaas-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org, billsumnerlinux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, li.zhang6-VXdhtT5mjnY@public.gmane.org, dwmw2-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, vgoyal-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org List-Id: iommu@lists.linux-foundation.org On 05/13/15 at 09:45am, Li, ZhenHua wrote: > On 05/12/2015 04:17 PM, Dave Young wrote: > >On 05/11/15 at 05:52pm, Li, Zhen-Hua wrote: > >>Add context entry functions needed for kdump. > >>+/* > >>+ * Fix Crashdump failure caused by leftover DMA through a hardware IOMMU > >>+ * > >>+ * Fixes the crashdump kernel to deal with an active iommu and legacy > >>+ * DMA from the (old) panicked kernel in a manner similar to how legacy > >>+ * DMA is handled when no hardware iommu was in use by the old kernel -- > >>+ * allow the legacy DMA to continue into its current buffers. > >>+ * > >>+ * In the crashdump kernel, this code: > >>+ * 1. skips disabling the IOMMU's translating. > >>+ * 2. Do not re-enable IOMMU's translating. > >>+ * 3. In kdump kernel, use the old root entry table. > >>+ * 4. Allocate pages for new context entry, copy data from old context entries > >>+ * in the old kernel to the new ones. > >>+ * > >>+ * In other kinds of kernel, for example, a kernel started by kexec, > >>+ * do the same thing as crashdump kernel. > >>+ */ > >>+ > >>+ > > > >Above comments should come along with the code changes instead of putting it > >in this patch. > > > >BTW, there's one more blank line at the end.. > Code change is in 00/10, the cover letter. I means the real code, not the changelog. > And the blank does not matter, I checked the patch with > scripts/checkpatch.pl, no warnings, no errors. Why add two line breaks if one is enough? Adding such check in checkpatch.pl make sense to me actually. Thanks Dave