From b21046d2eaad49c6e943c1618ba07a9b7da9cd0d Mon Sep 17 00:00:00 2001
From: Roger Pau Monne <roger.pau@entel.upc.edu>
Date: Thu, 19 Jan 2012 11:21:10 +0100
Subject: libxc: add comment to why NetBSD return hypercall->retval

Added a comment that explains why NetBSD return hypercall->retval on
success.

Signed-off-by: Roger Pau Monne <roger.pau@entel.upc.edu>
Acked-by: Ian Campbell <ian.campbell.com>
Committed-by: Ian Jackson <ian.jackson.citrix.com>
Reported-by: Olaf Hering <olaf@aepfle.de>
---
 tools/libxc/xc_netbsd.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/tools/libxc/xc_netbsd.c b/tools/libxc/xc_netbsd.c
index 9782a3423a..b6d67bbb8c 100644
--- a/tools/libxc/xc_netbsd.c
+++ b/tools/libxc/xc_netbsd.c
@@ -96,6 +96,12 @@ static int netbsd_privcmd_hypercall(xc_interface *xch, xc_osdep_handle h, privcm
     int fd = (int)h;
     int error = ioctl(fd, IOCTL_PRIVCMD_HYPERCALL, hypercall);
 
+    /*
+     * Since NetBSD ioctl can only return 0 on success or < 0 on
+     * error, if we want to return a value from ioctl we should
+     * do so by setting hypercall->retval, to mimic Linux ioctl
+     * implementation.
+     */
     if (error < 0)
         return -errno;
     else
-- 
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