Re: [Xen-devel] [PATCH 04/11] Disable the mfn_is_ram() check, it doesn't work correctly on all systems

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2012-09-27 at 18:09 +0100, Matthew Fioravante wrote:
> This patch disables the mfn_is_ram check in mini-os. The current check
> is insufficient and fails on some systems with larger than 4gb memory.
> 
> Signed-off-by: Matthew Fioravante <matthew.fioravante@xxxxxxxxxx>
> Acked-by: Samuel Thibault <samuel.thibault@xxxxxxxxxxxx>

Further down the thread with the Ack Samuel said:
        We can probably just remove the check in __do_ioremap, which
        AFAIK is the only call.

since this function is a bit pointless now.

> 
> diff --git a/extras/mini-os/arch/x86/mm.c b/extras/mini-os/arch/x86/mm.c
> index 80aceac..5813a08 100644
> --- a/extras/mini-os/arch/x86/mm.c
> +++ b/extras/mini-os/arch/x86/mm.c
> @@ -850,6 +850,8 @@ unsigned long alloc_contig_pages(int order, unsigned int 
> addr_bits)
>  static long system_ram_end_mfn;
>  int mfn_is_ram(unsigned long mfn)
>  {
> +   /* This is broken on systems with large ammounts of ram. Always return 0 
> for now */
> +    return 0;
>      /* very crude check if a given MFN is memory or not. Probably should
>       * make this a little more sophisticated ;) */
>      return (mfn <= system_ram_end_mfn) ? 1 : 0;



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