Subject: Re: [RFC/PATCH 3/4] powerpc/64/kexec: Copy image with MMU off when possible

From: Balbir Singh <[email-masked]>
Date: Fri, 8 Jul 2016 13:08:44 +1000

On 06/07/16 14:35, Benjamin Herrenschmidt wrote:
> 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 <[email-masked]>
> ---
> Currently only compile tested

This makes sense

Acked-by: Balbir Singh <[email-masked]>