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Date: Fri, 2 Mar 2012 11:01:16 +1300
From: Alexey Korolev <alexey.korolev@endace.com>
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Subject: Re: [Qemu-devel] [SeaBIOS] [PATCH 4/6] Mapping of BARs and Bridge
	regions
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To: Gerd Hoffmann <kraxel@redhat.com>
Cc: sfd@endace.com, seabios@seabios.org, mst@redhat.com, qemu-devel@nongnu.org, avi@redhat.com

On 01/03/12 22:22, Gerd Hoffmann wrote:
> On 03/01/12 07:57, Alexey Korolev wrote:
>> In pci_bios_map_regions() we try to reserve memory for 
>> all entries of root bus regions.
>> If pci_bios_init_root_regions() fails - e.g no enough space, we create two new pci_regions:
>> r64pref, r64mem and migrate all entries which are 64bit capable to them. Migration process
>> is very simple: delete the entry from one list add to another.
> It isn't that simple.  There are a bunch of constrains.  First the
> bridge must be 64bit capable.  All bridges up to the root bus in case of
> nested bridges.  Second all other prefmem bars of devices behind the
> bridge must be 64bit capable too.  Again, in case of nested bridges this
> applies to all devices behind the toplevel bridge.
It must be simple as we derive 64bit flag from devices behind the bridge at the stage of building topology.

In other words if the entry at the stage of mapping has 64bit flag it means that the entry and all
the entries behind it are 64bit capable.

 

+    for (i = (MaxPCIBus + 1) * PCI_REGION_TYPE_COUNT ; i < 0; i--) {
+	 .................
+        is64bit = this_entry->is64bit;
+        size = 0;
+        foreach_region_entry(&regions[i-1], entry) {
+            size += entry->size;
+            is64bit &= entry->is64bit;
+        }
	 .................
+        this_entry->is64bit = is64bit;