On Tue, 10 Dec 2019 10:49:43 +0200
Tzvetomir Stoyanov <tz.stoyanov@xxxxxxxxx> wrote:
> > > + if (guest_config) {
> > > + /* If -C is specified, prepend clock to all guest VM flags */
> > > + for_all_instances(instance) {
> > > + if (top_instance.ftrace->clock) {
> > > + if (is_guest(instance)) {
> >
> > We should only append this, if the guest didn't have a clock set
> > already. As the change log seems to say, if the user states a "-C
> > clock" for the guest, that should take precedence over the host clock
> > set. That is, a user may specifically state that they are using a
> > different clock. If we have frequency and offset set, it should still
> > work with different clocks.
>
> The guest config string is not parsed in the host context, that's why the host
> doesn't know if a guest has an explicit "-C clock" argument.
> I can parse the guest config here, but this will complicate the implementation.
> Using the current approach still guarantees that the user specified
> config has higher
> priority than injected one - add_argv() API prepends to the beginning
> of the string, so
> user arguments are always after the injected one. When guest parses
> the string, in case of
> duplicated "-C clock" arguments, the last one wins.
I'm confused. I'm looking at this:
for (;;) {
[..]
switch (c) {
[..]
case 'A':
[..]
ctx->instance->flags |= BUFFER_FL_GUEST;
[..]
case 'C':
ctx->instance->ftrace->clock = optarg;
guest_config = true;
break;
[..]
}
[..]
}
[..]
if (guest_config) {
/* If -C is specified, prepend clock to all guest VM flags */
for_all_instances(instance) {
if (top_instance.ftrace->clock) {
Why can't we have here:
if (top_instance.ftrace->clock && !instance->ftrace->clock)
If the guest instance was given a -C, I would think we don't want to add
another -C to pass to that guest?
-- Steve
if (is_guest(instance)) {
add_argv(instance,
(char *)top_instance.ftrace->clock,
true);
add_argv(instance, "-C", true);
}
}
}
}
|