Re: [PATCH v9 3/10] x86, asm: Change is_new_memtype_allowed() for WT

[Thomas Gleixner]

On Wed, 13 May 2015, Toshi Kani wrote:

> __ioremap_caller() calls reserve_memtype() to set new_pcm
> (existing map type if any), and then calls
> is_new_memtype_allowed() to verify if converting to new_pcm
> is allowed when pcm (request type) is different from new_pcm.
> 
> When WT is requested, the caller expects that writes are
> ordered and uncached.  Therefore, this patch changes
> is_new_memtype_allowed() to disallow the following cases.
> 
>  - If the request is WT, mapping type cannot be WB
>  - If the request is WT, mapping type cannot be WC
> 
> Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>

Reviewed-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
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