From c9e5777ede291cc8a5e9166e6c1979174b545c96 Mon Sep 17 00:00:00 2001
From: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Date: Wed, 1 Aug 2018 11:56:16 +0200
Subject: [PATCH] virtio: clarify feature negotiation failure

Change-Id: Ifb1566033569af0b3cf4a9dfbc8094a9883c7622
Signed-off-by: Dariusz Stojaczyk <dariuszx.stojaczyk@intel.com>
Reviewed-on: https://review.gerrithub.io/420980
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Chandler-Test-Pool: SPDK Automated Test System <sys_sgsw@intel.com>
Reviewed-by: Ben Walker <benjamin.walker@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
---
 lib/virtio/virtio.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/lib/virtio/virtio.c b/lib/virtio/virtio.c
index 511803ed25..b03034cffc 100644
--- a/lib/virtio/virtio.c
+++ b/lib/virtio/virtio.c
@@ -266,6 +266,9 @@ virtio_negotiate_features(struct virtio_dev *dev, uint64_t req_features)
 	virtio_dev_set_status(dev, VIRTIO_CONFIG_S_FEATURES_OK);
 	if (!(virtio_dev_get_status(dev) & VIRTIO_CONFIG_S_FEATURES_OK)) {
 		SPDK_ERRLOG("failed to set FEATURES_OK status!\n");
+		/* either the device failed, or we offered some features that
+		 * depend on other, not offered features.
+		 */
 		return -EINVAL;
 	}