On Thu, 5 Dec 2019 14:05:19 +0100 Philippe Mathieu-Daudé <philmd(a)redhat.com&gt; 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 <lersek(a)redhat.com&gt; >> Reviewed-by: Daniel P. Berrangé <berrange(a)redhat.com&gt; >> Reviewed-by: Michael Roth <mdroth(a)linux.vnet.ibm.com&gt; >> Signed-off-by: Cornelia Huck <cohuck(a)redhat.com&gt; >> --- >> >> 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) { >> >