[Xen-devel] [PATCH] x86: adjust available memory calculation for Dom0 construction

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

With a large number of CPUs, the amount of memory needed to construct
the vCPU structures for Dom0 becomes significant and hence should be
accounted for when calculating the amount of memory to pass to Dom0.

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>

--- 2010-03-09.orig/xen/arch/x86/domain_build.c 2010-03-09 00:00:00.000000000 
+0100
+++ 2010-03-09/xen/arch/x86/domain_build.c      2010-03-10 16:49:52.000000000 
+0100
@@ -155,6 +155,13 @@ static unsigned long __init compute_dom0
     unsigned long min_pages = dom0_min_nrpages;
     unsigned long max_pages = dom0_max_nrpages;
 
+    avail -= (opt_dom0_max_vcpus - 1UL)
+             << get_order_from_bytes(sizeof(struct vcpu));
+#ifdef __x86_64__
+    if ( sizeof_long == sizeof(int) )
+        avail -= opt_dom0_max_vcpus - 1;
+#endif
+
     /*
      * If domain 0 allocation isn't specified, reserve 1/16th of available
      * memory for things like DMA buffers. This reservation is clamped to

x86-dom0-alloc-avail.patch
Description: Text document

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