From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [RFC][PATCH 12/13] hvmloader/pci: skip reserved
	ranges
Date: Fri, 15 May 2015 16:16:02 +0800
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To: Jan Beulich <JBeulich@suse.com>
Cc: tim@xen.org, kevin.tian@intel.com, wei.liu2@citrix.com, ian.campbell@citrix.com, andrew.cooper3@citrix.com, Ian.Jackson@eu.citrix.com, xen-devel@lists.xen.org, stefano.stabellini@citrix.com, yang.z.zhang@intel.com
List-Id: xen-devel@lists.xenproject.org

On 2015/5/15 15:44, Jan Beulich wrote:
>>>> On 15.05.15 at 09:34, <tiejun.chen@intel.com> wrote:
>> So I think we may need to adjust pci_mem_start like this,
>>
>> @@ -301,6 +301,19 @@ void pci_setup(void)
>>                pci_mem_start <<= 1;
>>        }
>>
>> +    /* Relocate PCI memory that overlaps reserved space, like RDM. */
>> +    for ( j = 0; j < memory_map.nr_map ; j++ )
>> +    {
>> +        if ( memory_map.map[j].type != E820_RAM )
>> +        {
>> +            reserved_end = memory_map.map[j].addr + memory_map.map[j].size;
>> +            if ( check_overlap(pci_mem_start, pci_mem_end,
>> +                               memory_map.map[j].addr,
>> +                               memory_map.map[j].size) )
>> +                pci_mem_start -= memory_map.map[j].size >> PAGE_SHIFT;
>> +        }
>> +    }
>> +
>>        if ( mmio_total > (pci_mem_end - pci_mem_start) )
>>        {
>>            printf("Low MMIO hole not large enough for all devices,"
>>
>> Right?
>
> I think that gets you in the right direction, but isn't enough, as it
> doesn't account for (unavoidable) gaps (BARs are always a power
> of 2 in size and accordingly aligned).

Right.

But as you see, we always take this action, >> PAGE_SHIFT, so this means 
its always a sort of power of 2.

Additionally, lets go back here,

         if ( (base < resource->base) || (base > resource->max) )
         {
             printf("pci dev %02x:%x bar %02x size "PRIllx": no space for "
                    "resource!\n", devfn>>3, devfn&7, bar_reg,
                    PRIllx_arg(bar_sz));
             continue;
         }

I mean even without rdm, the original codes don't consider handling this 
lack of space from a alignment in advance, right?


Thanks
Tiejun