Message-ID: <5552ACB9.5050309@hp.com>
Date: Wed, 13 May 2015 09:45:29 +0800
From: "Li, ZhenHua" <zhen-hual@hp.com>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0
MIME-Version: 1.0
To: Dave Young <dyoung@redhat.com>
CC: dwmw2@infradead.org, indou.takao@jp.fujitsu.com, bhe@redhat.com,
        joro@8bytes.org, vgoyal@redhat.com, iommu@lists.linux-foundation.org,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        kexec@lists.infradead.org, alex.williamson@redhat.com,
        ddutile@redhat.com, ishii.hironobu@jp.fujitsu.com, bhelgaas@google.com,
        doug.hatch@hp.com, jerry.hoemann@hp.com, tom.vaden@hp.com,
        li.zhang6@hp.com, lisa.mitchell@hp.com, billsumnerlinux@gmail.com,
        rwright@hp.com, "Li, ZhenHua" <zhen-hual@hp.com>
Subject: Re: [PATCH v11 02/10] iommu/vt-d: Items required for kdump
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>
In-Reply-To: <20150512081723.GC4561@localhost.localdomain>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1542
Lines: 38

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.
And the blank does not matter, I checked the patch with 
scripts/checkpatch.pl,  no warnings, no errors.


--
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/