Re: [Xen-devel] [PATCH] MAX_DMADOM_PFN

[Jon Mason <jdmason@xxxxxxxxxx>]

On Thu, Jan 26, 2006 at 10:19:20AM +0900, Isaku Yamahata wrote:
> 
> made MAX_DMADOM_PFN page size aware.
> 4K page size was assumed, however it is not true for xen/ia64.
> It should also be possible for arch dependent code to override it.
> 
> # HG changeset patch
> # User yamahata@xxxxxxxxxxxxx
> # Node ID 0c2b703c79333c01e4cccef1fbac1d01c6c7daa7
> # Parent  5b004f4e76cf90ef6f7155a4822e63b9e33cf7d8
> made MAX_DMADOM_PFN aware of page size.
> 4K page size was assumed. It is not true for xen/ia64 by default.
> It should also be possible for arch dependent code to override it.
> 
> Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
> 
> diff -r 5b004f4e76cf -r 0c2b703c7933 xen/common/page_alloc.c
> --- a/xen/common/page_alloc.c Wed Jan 25 23:35:22 2006 +0100
> +++ b/xen/common/page_alloc.c Thu Jan 26 10:09:39 2006 +0900
> @@ -216,7 +216,9 @@
>  #define NR_ZONES    3
>  
>  
> -#define MAX_DMADOM_PFN 0x7FFFFUL /* 31 addressable bits */
> +#ifndef MAX_DMADOM_PFN /* arch-depedent code can override */
> +#define MAX_DMADOM_PFN (0x7FFFFFFFUL >> PAGE_SHIFT) /* 31 addressable bits */
> +#endif
>  #define pfn_dom_zone_type(_pfn)                                 \
>      (((_pfn) <= MAX_DMADOM_PFN) ? MEMZONE_DMADOM : MEMZONE_DOM)

Why only 31bits?

Also, wouldn't it be better to define this in <asm/dma.h>?  x86-64 added
similar #defines to include/asm-x86_64/dma.h relatively recently (see
MAX_DMA32_PFN).  This would be a good model to follow.

Thanks,
Jon

>  
> 
> -- 
> yamahata

> # HG changeset patch
> # User yamahata@xxxxxxxxxxxxx
> # Node ID 0c2b703c79333c01e4cccef1fbac1d01c6c7daa7
> # Parent  5b004f4e76cf90ef6f7155a4822e63b9e33cf7d8
> made MAX_DMADOM_PFN aware of page size.
> 4K page size was assumed. It is not true for xen/ia64 by default.
> It should also be possible for arch dependent code to override it.
> 
> Signed-off-by: Isaku Yamahata <yamahata@xxxxxxxxxxxxx>
> 
> diff -r 5b004f4e76cf -r 0c2b703c7933 xen/common/page_alloc.c
> --- a/xen/common/page_alloc.c Wed Jan 25 23:35:22 2006 +0100
> +++ b/xen/common/page_alloc.c Thu Jan 26 10:09:39 2006 +0900
> @@ -216,7 +216,9 @@
>  #define NR_ZONES    3
>  
>  
> -#define MAX_DMADOM_PFN 0x7FFFFUL /* 31 addressable bits */
> +#ifndef MAX_DMADOM_PFN /* arch-depedent code can override */
> +#define MAX_DMADOM_PFN (0x7FFFFFFFUL >> PAGE_SHIFT) /* 31 addressable bits */
> +#endif
>  #define pfn_dom_zone_type(_pfn)                                 \
>      (((_pfn) <= MAX_DMADOM_PFN) ? MEMZONE_DMADOM : MEMZONE_DOM)
>  

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