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Re: [Xen-devel] [RFC][PATCH 12/13] hvmloader/pci: skip reserved ranges



On 2015/5/15 15:44, Jan Beulich wrote:
On 15.05.15 at 09:34, <tiejun.chen@xxxxxxxxx> 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

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