From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [v10][PATCH 06/16] hvmloader/pci: Try to avoid
 placing BARs in RMRRs
Date: Mon, 20 Jul 2015 22:06:07 +0800
Message-ID: <55AD004F.7060905@intel.com>
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To: George Dunlap <george.dunlap@citrix.com>, Jan Beulich <JBeulich@suse.com>, George Dunlap <George.Dunlap@eu.citrix.com>
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>>> +/* Find the lowest RMRR higher than base. */
>>> +static int find_next_rmrr(uint32_t base)
>>> +{
>>> +    unsigned int i;
>>> +    int next_rmrr = -1;
>>> +    uint64_t min_base = (1ull << 32);
>>> +
>>> +    for ( i = 0; i < memory_map.nr_map ; i++ )
>>> +    {
>>> +        if ( memory_map.map[i].type == E820_RESERVED &&
>>> +             memory_map.map[i].addr > base &&
>>> +             memory_map.map[i].addr < min_base )
>>> +        {
>>> +            next_rmrr = i;
>>> +            min_base = memory_map.map[i].addr;
>>> +        }
>>> +    }
>>> +    return next_rmrr;
>>> +}
>>
>> Considering _both_ callers, I think the function should actually return
>> the lowest RMRR higher than or equal to base.
>
> You mean instead of strictly greater than the base.
>
>> Or wait - we actually
>> need to find the lowest RMRR the _end_ of which is higher than base.
>
> Yes, you're right: there's always a risk that pci_mem_start will *start*
> in the middle of a range.  Looking for the next *end* is more robust.
>

Sorry this is not very clear to me so are you saying something like this?

     for ( i = 0; i < memory_map.nr_map ; i++ )
     {
         end = memory_map.map[i].addr + memory_map.map[i].size;

         if ( memory_map.map[i].type == E820_RESERVED &&
              end > base &&
              memory_map.map[i].addr < min_base )
         {
             next_rmrr = i;
             min_base = memory_map.map[i].addr;
         }
     }


Thanks
Tiejun