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Subject: Re: [PATCH V2 4/5] powerpc/64/kexec: Copy image with MMU off when
 possible
To: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>,
 benh@kernel.crashing.org, paulus@samba.org, mpe@ellerman.id.au
References: <1471596759-3396-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
 <1471596759-3396-5-git-send-email-aneesh.kumar@linux.vnet.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org
From: Balbir Singh <bsingharora@gmail.com>
Message-ID: <218c621a-8873-47a5-f1f5-21d530cc0005@gmail.com>
Date: Tue, 23 Aug 2016 10:21:13 +1000
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On 19/08/16 18:52, Aneesh Kumar K.V wrote:
> From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> 
> Currently we turn the MMU off after copying the image, and we make
> sure there is no overlap between the hash table and the target pages
> in that case.
> 
> That doesn't work for Radix however. In that case, the page tables
> are scattered and we can't really enforce that the target of the
> image isn't overlapping one of them.
> 
> So instead, let's turn the MMU off before copying the image in radix
> mode. Thankfully, in radix mode, even under a hypervisor, we know we
> don't have the same kind of RMA limitations that hash mode has.
> 
> While at it, also turn the MMU off early when using hash in non-LPAR
> mode, that way we can get rid of the collision check completely.
> 
> Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>

Looks good

Acked-by: Balbir Singh <bsingharora@gmail.com>