| Message ID | 1327667215-5411-2-git-send-email-stefano.stabellini@eu.citrix.com |
|---|---|
| State | New |
| Headers | show |
On 01/27/2012 01:26 PM, Stefano Stabellini wrote: > rtc_clock is only used by the RTC emulator (mc146818rtc.c), however Xen > has its own RTC emulator in the hypervisor so we can disable it. > > Signed-off-by: Stefano Stabellini<stefano.stabellini@eu.citrix.com> > --- > xen-all.c | 1 + > 1 files changed, 1 insertions(+), 0 deletions(-) > > diff --git a/xen-all.c b/xen-all.c > index d1fc597..bf183f7 100644 > --- a/xen-all.c > +++ b/xen-all.c > @@ -513,6 +513,7 @@ void xen_vcpu_init(void) > qemu_register_reset(xen_reset_vcpu, first_cpu); > xen_reset_vcpu(first_cpu); > } > + qemu_clock_enable(rtc_clock, false); > } > > /* get the ioreq packets from share mem */ Depending on "-rtc clock=vm" or "-rtc clock=rt", this may not be true. Why do you need to instantiate an RTC at all? Paolo
On Fri, 27 Jan 2012, Paolo Bonzini wrote: > On 01/27/2012 01:26 PM, Stefano Stabellini wrote: > > rtc_clock is only used by the RTC emulator (mc146818rtc.c), however Xen > > has its own RTC emulator in the hypervisor so we can disable it. > > > > Signed-off-by: Stefano Stabellini<stefano.stabellini@eu.citrix.com> > > --- > > xen-all.c | 1 + > > 1 files changed, 1 insertions(+), 0 deletions(-) > > > > diff --git a/xen-all.c b/xen-all.c > > index d1fc597..bf183f7 100644 > > --- a/xen-all.c > > +++ b/xen-all.c > > @@ -513,6 +513,7 @@ void xen_vcpu_init(void) > > qemu_register_reset(xen_reset_vcpu, first_cpu); > > xen_reset_vcpu(first_cpu); > > } > > + qemu_clock_enable(rtc_clock, false); > > } > > > > /* get the ioreq packets from share mem */ > > Depending on "-rtc clock=vm" or "-rtc clock=rt", this may not be true. Good point. I should check for rtc_clock == host_clock. > Why do you need to instantiate an RTC at all? I don't, in fact in previous versions of this patch series I tried to do that but it is difficult and makes the common code worse, so I followed Anthony's suggestion of just disabling the rtc_clock.
On 01/30/2012 12:56 PM, Stefano Stabellini wrote: >> > Depending on "-rtc clock=vm" or "-rtc clock=rt", this may not be true. > > Good point. > I should check for rtc_clock == host_clock. > >> > Why do you need to instantiate an RTC at all? > I don't, in fact in previous versions of this patch series I tried to do > that but it is difficult and makes the common code worse, so I followed > Anthony's suggestion of just disabling the rtc_clock. I see. It shouldn't surprise you that I completely disagree with Anthony on this. :) Paolo
On Mon, 30 Jan 2012, Paolo Bonzini wrote: > On 01/30/2012 12:56 PM, Stefano Stabellini wrote: > >> > Depending on "-rtc clock=vm" or "-rtc clock=rt", this may not be true. > > > > Good point. > > I should check for rtc_clock == host_clock. > > > >> > Why do you need to instantiate an RTC at all? > > I don't, in fact in previous versions of this patch series I tried to do > > that but it is difficult and makes the common code worse, so I followed > > Anthony's suggestion of just disabling the rtc_clock. > > I see. It shouldn't surprise you that I completely disagree with > Anthony on this. :) I am OK with both approaches, but I can see the benefits of reducing this patch to (almost) a one-liner.
On 01/30/2012 05:59 AM, Paolo Bonzini wrote: > On 01/30/2012 12:56 PM, Stefano Stabellini wrote: >>> > Depending on "-rtc clock=vm" or "-rtc clock=rt", this may not be true. >> >> Good point. >> I should check for rtc_clock == host_clock. >> >>> > Why do you need to instantiate an RTC at all? >> I don't, in fact in previous versions of this patch series I tried to do >> that but it is difficult and makes the common code worse, so I followed >> Anthony's suggestion of just disabling the rtc_clock. > > I see. It shouldn't surprise you that I completely disagree with Anthony on > this. :) Give me some credit at least... The original patches didn't disable the RTC, it introduced a half-neutered Xen specific RTC. My original suggestion (which I still think is the best approach) is to change the RTC emulation to not use a second timer at all. Regards, Anthony Liguori > Paolo >
On 01/30/2012 08:28 PM, Anthony Liguori wrote: >> >> I see. It shouldn't surprise you that I completely disagree with >> Anthony on this. :) > > Give me some credit at least... > > The original patches didn't disable the RTC, it introduced a > half-neutered Xen specific RTC. Ah. :) > My original suggestion (which I still think is the best approach) is to > change the RTC emulation to not use a second timer at all. Yes, that would be really the best approach. I tried and it's pretty hard, but we can give it a second try. Paolo
diff --git a/xen-all.c b/xen-all.c index d1fc597..bf183f7 100644 --- a/xen-all.c +++ b/xen-all.c @@ -513,6 +513,7 @@ void xen_vcpu_init(void) qemu_register_reset(xen_reset_vcpu, first_cpu); xen_reset_vcpu(first_cpu); } + qemu_clock_enable(rtc_clock, false); } /* get the ioreq packets from share mem */
rtc_clock is only used by the RTC emulator (mc146818rtc.c), however Xen has its own RTC emulator in the hypervisor so we can disable it. Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com> --- xen-all.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)