* the current maximum rather than the static maximum. In this
* case the e820 map provided to us will cover the static
* maximum region.
+ *
+ * The dom0_mem=min:X,max:Y tweaks options differently depending
+ * on the version, but in general this is what we get:
+ * | XENMEM_maximum_reser | nr_pages
+ * --------------++-----------------------+-------------------
+ * no dom0_mem | INT_MAX | max_phys_pfn
+ * =3G | INT_MAX | 786432
+ * =max:3G | 786432 | 786432
+ * =min:1G,max:3G| INT_MAX | max_phys_fn
+ * =1G,max:3G | INT_MAX | 262144
+ * =min:1G,max:3G,2G | INT_MAX | max_phys_fn
+ *
+ * The =3G is often used and it lead to us initially setting
+ * 786432 and allowing dom0 to balloon up to the max_physical_pfn.
+ * This is at odd with the classic XenOClassic so lets emulate
+ * the classic behavior.
*/
if (xen_initial_domain()) {
ret = HYPERVISOR_memory_op(XENMEM_maximum_reservation, &domid);
if (ret > 0)
max_pages = ret;
+ if (ret == -1UL)
+ max_pages = xen_start_info->nr_pages;
}
return min(max_pages, MAX_DOMAIN_PAGES);