KVM: Document replacements for KVM_EXIT_HYPERCALL

Signed-off-by: Avi Kivity <avi@redhat.com>
git-mirror · May 17, 2010 · 647dc49 · 647dc49
1 parent 05b0ab1
commit 647dc49
Showing 1 changed file with 3 additions and 1 deletion.
diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
@@ -974,7 +974,9 @@ pending operations.
 			__u32 pad;
 		} hypercall;
 
-Unused.
+Unused.  This was once used for 'hypercall to userspace'.  To implement
+such functionality, use KVM_EXIT_IO (x86) or KVM_EXIT_MMIO (all except s390).
+Note KVM_EXIT_IO is significantly faster than KVM_EXIT_MMIO.
 
 		/* KVM_EXIT_TPR_ACCESS */
 		struct {