From mboxrd@z Thu Jan  1 00:00:00 1970
From: Keir Fraser <keir.xen@gmail.com>
Subject: Re: [PATCH v2 9/9] xen: support RAM at addresses 0 and
	4096
Date: Fri, 13 Sep 2013 04:48:04 -0700
Message-ID: <CE584984.5DCEB%keir.xen@gmail.com>
References: <1379072437-28099-9-git-send-email-ian.campbell@citrix.com>
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To: Ian Campbell <ian.campbell@citrix.com>, xen-devel@lists.xen.org
Cc: julien.grall@linaro.org, tim@xen.org, jbeulich@suse.com, andre.przywara@linaro.org, stefano.stabellini@eu.citrix.com
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On 13/09/2013 04:40, "Ian Campbell" <ian.campbell@citrix.com> wrote:

> Currently the mapping from pages to zones causes the page at zero to go into
> zone -1 and the page at 4096 to go into zone 0, which is the Xen zone
> (confusing various assertions).
> 
> Arrange instead for the mapping to be such that zone 0 is always reserved for
> Xen and all other pages map to a zone >= 1.
> 
> Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> Cc: keir@xen.org
> Cc: jbeulich@suse.com

Acked-by: Keir Fraser <keir@xen.org>

> ---
> v2: fixup my arithmetic
> ---
>  xen/common/page_alloc.c |    6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
> index 41251b2..fb8187b 100644
> --- a/xen/common/page_alloc.c
> +++ b/xen/common/page_alloc.c
> @@ -257,11 +257,11 @@ unsigned long __init alloc_boot_pages(
>   */
>  
>  #define MEMZONE_XEN 0
> -#define NR_ZONES    (PADDR_BITS - PAGE_SHIFT)
> +#define NR_ZONES    (PADDR_BITS - PAGE_SHIFT + 1)
>  
> -#define bits_to_zone(b) (((b) < (PAGE_SHIFT + 1)) ? 0 : ((b) - PAGE_SHIFT -
> 1))
> +#define bits_to_zone(b) (((b) < (PAGE_SHIFT + 1)) ? 1 : ((b) - PAGE_SHIFT))
>  #define page_to_zone(pg) (is_xen_heap_page(pg) ? MEMZONE_XEN :  \
> -                          (fls(page_to_mfn(pg)) - 1))
> +                          (fls(page_to_mfn(pg)) ? : 1))
>  
>  typedef struct page_list_head
> heap_by_zone_and_order_t[NR_ZONES][MAX_ORDER+1];
>  static heap_by_zone_and_order_t *_heap[MAX_NUMNODES];