This behaviour has been confirmed by inspection on:
- Linux
- NetBSD & FreeBSD (NB: hcall->retval is the hypercall return value
only for values >= 0. For negative values the underlying privcmd
driver translates the value from Xen to {Net,Free}BSD errno space
and returns it as the result of the ioctl, which becomes
ret=-1/errno=EFOO in userspace)
- MiniOS (which takes care of errno in this library)
Signed-off-by: Ian Campbell <ian.campb...@citrix.com>
Acked-by: Wei Liu <wei.l...@citrix.com>
Acked-by: Ian Jackson <ian.jack...@eu.citrix.com>
Acked-by: Roger Pau Monné <roger....@citrix.com>
Cc: Roger Pau Monné <roger....@citrix.com>
---
v7: Noted NetBSD behaviour
v6: New patch
---
tools/libs/call/include/xencall.h | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/tools/libs/call/include/xencall.h
b/tools/libs/call/include/xencall.h
index 0d91aa8..3f325f0 100644
--- a/tools/libs/call/include/xencall.h
+++ b/tools/libs/call/include/xencall.h
@@ -46,6 +46,21 @@ int xencall_close(xencall_handle *xcall);
/*
* Call hypercalls with varying numbers of arguments.
+ *
+ * On success the return value of the hypercall is the return value of
+ * the xencall function. On error these functions set errno and
+ * return -1.
+ *
+ * The errno values will be either:
+ * - The Xen hypercall error return (from xen/include/public/errno.h)
+ * translated into the corresponding local value for that POSIX error.
+ * - An errno value produced by the OS driver or the library
+ * implementation. Such values may be defined by POSIX or by the OS.
+ *
+ * Note that under some circumstances it will not be possible to tell
+ * whether an error came from Xen or from the OS/library.
+ *
+ * These functions never log.
*/
int xencall0(xencall_handle *xcall, unsigned int op);
int xencall1(xencall_handle *xcall, unsigned int op,
--
2.1.4
_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel
