-----Original Message-----
From: Jason Wang <redacted>
Sent: Sunday, October 8, 2023 12:36 PM
To: Liming Wu <redacted>
Cc: Michael S . Tsirkin <mst@redhat.com>; kvm@vger.kernel.org;
virtualization@lists.linux-foundation.org; netdev@vger.kernel.org; linux-
kernel@vger.kernel.org; 398776277@qq.com
Subject: Re: [PATCH 2/2] tools/virtio: Add hints when module is not installed

On Tue, Sep 26, 2023 at 1:00 PM [off-list ref] wrote:

quoted

From: Liming Wu <redacted>

Need to insmod vhost_test.ko before run virtio_test.
Give some hints to users.

Signed-off-by: Liming Wu <redacted>
---
 tools/virtio/virtio_test.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tools/virtio/virtio_test.c b/tools/virtio/virtio_test.c
index 028f54e6854a..ce2c4d93d735 100644
--- a/tools/virtio/virtio_test.c
+++ b/tools/virtio/virtio_test.c

@@ -135,6 +135,10 @@ static void vdev_info_init(struct vdev_info* dev,

unsigned long long features)

quoted

        dev->buf = malloc(dev->buf_size);
        assert(dev->buf);
        dev->control = open("/dev/vhost-test", O_RDWR);
+
+       if (dev->control < 0)
+               fprintf(stderr, "Install vhost_test module" \
+               "(./vhost_test/vhost_test.ko) firstly\n");

There should be many other reasons to fail for open().

Let's use strerror()?

Yes,  Thanks for the review. 
Please rechecked the code as follow:

--- a/tools/virtio/virtio_test.c
+++ b/tools/virtio/virtio_test.c

@@ -135,6 +135,11 @@ static void vdev_info_init(struct vdev_info* dev, unsigned long long features)
        dev->buf = malloc(dev->buf_size);
        assert(dev->buf);
        dev->control = open("/dev/vhost-test", O_RDWR);
+
+       if (dev->control == NULL)
+               fprintf(stderr,
+                       "%s: Check whether vhost_test.ko is installed.\n",
+                       strerror(errno));
        assert(dev->control >= 0);
        r = ioctl(dev->control, VHOST_SET_OWNER, NULL);
        assert(r >= 0);
 

Thanks