[PATCH 1/2] pci: new layout: driver must not write to bits>63

Since we never offer feature bits >63, driver must
not ack them.

Signed-off-by: Michael S. Tsirkin <>
---
 virtio-v1.0-wd01-part1-specification.txt | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/virtio-v1.0-wd01-part1-specification.txt b/virtio-v1.0-wd01-part1-specification.txt
index e6e7eee..71ddcc5 100644
--- a/virtio-v1.0-wd01-part1-specification.txt
+++ b/virtio-v1.0-wd01-part1-specification.txt
@@ -743,8 +743,9 @@ guest_feature_select
 	Selects which Feature Bits does guest_feature field refer to.
 	Value 0x0 selects Feature Bits 0 to 31
 	Value 0x1 selects Feature Bits 32 to 63
-	All other values cause writes to guest_feature to be ignored,
-	and reads to return 0.
+	When set to any other value, reads from guest_feature
+	return 0, writing 0 into guest_feature has no effect, and
+	writing any other value into guest_feature is an error.
 
 guest_feature
 
-- 
MST