OvmfPkg: VirtioFlush(): return the number of bytes written by the host

[mirror_edk2.git] / OvmfPkg / Include / Library / VirtioLib.h

diff --git a/OvmfPkg/Include/Library/VirtioLib.h b/OvmfPkg/Include/Library/VirtioLib.h
index 36527a523f28814b4e0ce0c0b5f53f12ca7da3d9..decd4418af3d997739e8f39fef3c32fa2bc23759 100644 (file)
--- a/OvmfPkg/Include/Library/VirtioLib.h
+++ b/OvmfPkg/Include/Library/VirtioLib.h
@@ -2,7 +2,7 @@
 \r
   Declarations of utility functions used by virtio device drivers.\r
 \r
-  Copyright (C) 2012, Red Hat, Inc.\r
+  Copyright (C) 2012-2016, Red Hat, Inc.\r
 \r
   This program and the accompanying materials are licensed and made available\r
   under the terms and conditions of the BSD License which accompanies this\r
@@ -167,6 +167,12 @@ VirtioAppendDesc (
                           Indices->HeadDescIdx identifies the head descriptor\r
                           of the descriptor chain.\r
 \r
+  @param[out] UsedLen     On success, the total number of bytes, consecutively\r
+                          across the buffers linked by the descriptor chain,\r
+                          that the host wrote. May be NULL if the caller\r
+                          doesn't care, or can compute the same information\r
+                          from device-specific request structures linked by the\r
+                          descriptor chain.\r
 \r
   @return              Error code from VirtIo->SetQueueNotify() if it fails.\r
 \r
@@ -179,7 +185,8 @@ VirtioFlush (
   IN     VIRTIO_DEVICE_PROTOCOL *VirtIo,\r
   IN     UINT16                 VirtQueueId,\r
   IN OUT VRING                  *Ring,\r
-  IN     DESC_INDICES           *Indices\r
+  IN     DESC_INDICES           *Indices,\r
+  OUT    UINT32                 *UsedLen    OPTIONAL\r
   );\r
 \r
 #endif // _VIRTIO_LIB_H_\r