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Re: [Xen-devel] [RFC][PATCH 3/5] tools:libxc: remove mmio BAR out of RMRR mappings



On 2014/8/8 23:49, Jan Beulich wrote:
On 07.08.14 at 13:02, <tiejun.chen@xxxxxxxxx> wrote:
@@ -300,6 +302,30 @@ static int setup_guest(xc_interface *xch,
          goto error_out;
      }

+    /* We need to move mmio range out of RMRR mapping. */
+    rc = xc_get_rmrr_map(xch, map, E820MAX);
+    if (rc < 0)
+    {
+        PERROR("Could not get RMRR info on domain");
+    }
+    else if ( rc )
+    {
+        for ( i = 0; i < rc; i++ )
+        {
+            rmrr_end = map[i].addr + map[i].size + 1;
+            if ( rmrr_end > mmio_start )
+            {
+                mmio_start = rmrr_end;
+            }
+        }

This seems way too simplistic - what if the RMRRs are referring to
memory regions extremely far apart?

+        mmio_size = (1ull << 32) - mmio_start;

Limiting things to 4Gb?

+        if ( mmio_size <= 0 )

mmio_size is an unsigned quantity, so this won't do what you intend.

Yes, you're right.

With a further consideration, mmio size should be configured so I think it may be enough just to check if current mmio is overlapping, then let user determine what next should do.

Please comments this in next revision directly.

Thanks
Tiejun

Jan



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