This behaviour has been confirmed by inspection on: - Linux - 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 FreeBSD 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> Cc: Roger Pau Monné <roger....@citrix.com> --- 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
