On Thu, 5 Dec 2019 14:05:19 +0100
Philippe Mathieu-Daudé <phi...@redhat.com> wrote:
> Hi Cornelia,
>
> On 12/5/19 12:53 PM, Cornelia Huck wrote:
> > The Posix implementation of guest-set-time invokes hwclock to
> > set/retrieve the time to/from the hardware clock. If hwclock
> > is not available, the user is currently informed that "hwclock
> > failed to set hardware clock to system time", which is quite
> > misleading. This may happen e.g. on s390x, which has a different
> > timekeeping concept anyway.
> >
> > Let's check for the availability of the hwclock command and
> > return QERR_UNSUPPORTED for guest-set-time if it is not available.
> >
> > Reviewed-by: Laszlo Ersek <ler...@redhat.com>
> > Reviewed-by: Daniel P. Berrangé <berra...@redhat.com>
> > Reviewed-by: Michael Roth <mdr...@linux.vnet.ibm.com>
> > Signed-off-by: Cornelia Huck <coh...@redhat.com>
> > ---
> >
> > v2->v3:
> > - added 'static' keyword to hwclock_path
> >
> > Not sure what tree this is going through; if there's no better place,
> > I can also take this through the s390 tree.
>
> s390 or trivial trees seems appropriate.
>
> >
> > ---
> > qga/commands-posix.c | 13 ++++++++++++-
> > 1 file changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> > index 1c1a165daed8..0be301a4ea77 100644
> > --- a/qga/commands-posix.c
> > +++ b/qga/commands-posix.c
> > @@ -156,6 +156,17 @@ void qmp_guest_set_time(bool has_time, int64_t
> > time_ns, Error **errp)
> > pid_t pid;
> > Error *local_err = NULL;
> > struct timeval tv;
> > + static const char hwclock_path[] = "/sbin/hwclock";
> > + static int hwclock_available = -1;
> > +
> > + if (hwclock_available < 0) {
> > + hwclock_available = (access(hwclock_path, X_OK) == 0);
> > + }
> > +
> > + if (!hwclock_available) {
> > + error_setg(errp, QERR_UNSUPPORTED);
>
> In include/qapi/qmp/qerror.h we have:
>
> /*
> * These macros will go away, please don't use in new code, and do not
> * add new ones!
> */
Sigh, it is really hard to keep track here :( I just copied from other
callers in this file...
>
> Maybe we can replace it by "this feature is not supported on this
> architecture"? (or without 'on this architecture').
This is not really architecture specific, you'd get this on any setup
that does not have /sbin/hwclock.
Q: Is libvirt doing anything with such an error message from QEMU? Do
we have the freedom to say e.g "guest-set-time is not supported" or so?
Or is it beneficial to print the same error message for any unsupported
feature?
>
> > + return;
> > + }
> >
> > /* If user has passed a time, validate and set it. */
> > if (has_time) {
> > @@ -195,7 +206,7 @@ void qmp_guest_set_time(bool has_time, int64_t time_ns,
> > Error **errp)
> >
> > /* Use '/sbin/hwclock -w' to set RTC from the system time,
> > * or '/sbin/hwclock -s' to set the system time from RTC. */
> > - execle("/sbin/hwclock", "hwclock", has_time ? "-w" : "-s",
> > + execle(hwclock_path, "hwclock", has_time ? "-w" : "-s",
> > NULL, environ);
> > _exit(EXIT_FAILURE);
> > } else if (pid < 0) {
> >
>
