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diff --git a/usr.sbin/bhyve/e820.c b/usr.sbin/bhyve/e820.c
--- a/usr.sbin/bhyve/e820.c
+++ b/usr.sbin/bhyve/e820.c
@@ -26,6 +26,16 @@
#define MB (1024 * KB)
#define GB (1024 * MB)
+/*
+ * Fix E820 memory holes:
+ * [ A0000, C0000) VGA
+ * [ C0000, 100000) ROM
+ */
+#define E820_VGA_MEM_BASE 0xA0000
+#define E820_VGA_MEM_END 0xC0000
+#define E820_ROM_MEM_BASE 0xC0000
+#define E820_ROM_MEM_END 0x100000
+
struct e820_element {
TAILQ_ENTRY(e820_element) chain;
uint64_t base;
@@ -204,6 +214,74 @@
return (0);
}
+static int
+e820_add_memory_hole(const uint64_t base, const uint64_t end)
+{
+ struct e820_element *element;
+ struct e820_element *ram_element;
+
+ assert(end >= base);
+
+ /*
+ * E820 table should be always sorted in ascending order. Therefore,
+ * search for an element which end is larger than the base parameter.
+ */
+ TAILQ_FOREACH(element, &e820_table, chain) {
+ if (element->end > base) {
+ break;
+ }
+ }
+
+ if (element == NULL || end <= element->base) {
+ /* Nothing to do. Hole already exists */
+ return (0);
+ }
+
+ /* Memory holes are only allowed in system memory */
+ assert(element->type == E820_TYPE_MEMORY);
+
+ if (base == element->base) {
+ /*
+ * New hole at system memory base boundary.
+ *
+ * Old table:
+ * [ 0x1000, 0x4000] RAM
+ * New table:
+ * [ 0x2000, 0x4000] RAM
+ */
+ element->base = end;
+ } else if (end == element->end) {
+ /*
+ * New hole at system memory end boundary.
+ *
+ * Old table:
+ * [ 0x1000, 0x4000] RAM
+ * New table:
+ * [ 0x1000, 0x3000] RAM
+ */
+ element->end = base;
+ } else {
+ /*
+ * New hole inside system memory entry. Split the system memory.
+ *
+ * Old table:
+ * [ 0x1000, 0x4000] RAM <-- element
+ * New table:
+ * [ 0x1000, 0x2000] RAM
+ * [ 0x3000, 0x4000] RAM <-- element
+ */
+ ram_element = e820_element_alloc(element->base, base,
+ E820_TYPE_MEMORY);
+ if (ram_element == NULL) {
+ return (ENOMEM);
+ }
+ TAILQ_INSERT_BEFORE(element, ram_element, chain);
+ element->base = end;
+ }
+
+ return (0);
+}
+
int
e820_init(struct vmctx *const ctx)
{
@@ -229,5 +307,17 @@
}
}
+ error = e820_add_memory_hole(E820_VGA_MEM_BASE, E820_VGA_MEM_END);
+ if (error) {
+ warnx("%s: Could not add VGA memory", __func__);
+ return (error);
+ }
+
+ error = e820_add_memory_hole(E820_ROM_MEM_BASE, E820_ROM_MEM_END);
+ if (error) {
+ warnx("%s: Could not add ROM area", __func__);
+ return (error);
+ }
+
return (0);
}

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