ACK: [PATCH] mtrr: allow uncached type for PCI prefetchable memory

[Colin Ian King]

On 16/11/2018 08:45, Alex Hung wrote:
> Buglink: https://bugs.launchpad.net/bugs/1781920
> 
> Intel® 64 and IA-32 Architectures Software Developer's Manual seems to
> suggest uncachable memory can be used for memory-mapped I/O.
> 
> Details can be found in Section 11.3.2 - Choosing a Memory Type
> 
> Signed-off-by: Alex Hung <alex.hung at canonical.com>
> ---
>  src/bios/mtrr/mtrr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/src/bios/mtrr/mtrr.c b/src/bios/mtrr/mtrr.c
> index 4948b55a..a614ffbb 100644
> --- a/src/bios/mtrr/mtrr.c
> +++ b/src/bios/mtrr/mtrr.c
> @@ -351,7 +351,7 @@ static int guess_cache_type(
>  
>  		if (pref) {
>  			*must = 0;
> -			*mustnot = WRITE_BACK | UNCACHED;
> +			*mustnot = WRITE_BACK;
>  		} else {
>  			*must = UNCACHED;
>  			*mustnot = (~UNCACHED) & (~DEFAULT);
> 

Lets see if there is any fall-out from this. I agree it seems a correct
choice with respect to the manual, so I think it should be OK.

Acked-by: Colin Ian King <colin.king at canonical.com>