| Message ID | 1470390377-228219-17-git-send-email-imammedo@redhat.com |
|---|---|
| State | New |
| Headers | show |
On Fri, Aug 05, 2016 at 11:46:15AM +0200, Igor Mammedov wrote: > Currently firmware uses 1 byte at 0x5F offset in RTC CMOS > to get number of CPUs present at boot. However 1 byte is > not enough to handle more than 255 CPUs. So add a new > fw_cfg file that would allow QEMU to tell it. > For compat reasons add file only for machine types that > support more than 255 CPUs. > > Signed-off-by: Igor Mammedov <imammedo@redhat.com> Do we really need this? Why differentiate between boot cpus and others? How about reusing the hotplug register, such that it looks just as if all CPUs were just added by hotplug? > --- > hw/i386/pc.c | 12 +++++++++++- > 1 file changed, 11 insertions(+), 1 deletion(-) > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > index c2cd5bd..2b5581a 100644 > --- a/hw/i386/pc.c > +++ b/hw/i386/pc.c > @@ -1235,9 +1235,11 @@ void pc_machine_done(Notifier *notifier, void *data) > PCMachineState *pcms = container_of(notifier, > PCMachineState, machine_done); > PCIBus *bus = pcms->bus; > + static uint16_t boot_cpus; > > /* set the number of CPUs */ > - rtc_set_memory(pcms->rtc, 0x5f, pc_present_cpus_count(pcms) - 1); > + boot_cpus = pc_present_cpus_count(pcms); > + rtc_set_memory(pcms->rtc, 0x5f, boot_cpus - 1); > > if (bus) { > int extra_hosts = 0; > @@ -1258,8 +1260,16 @@ void pc_machine_done(Notifier *notifier, void *data) > > acpi_setup(); > if (pcms->fw_cfg) { > + MachineClass *mc = MACHINE_GET_CLASS(pcms); > + > pc_build_smbios(pcms->fw_cfg); > pc_build_feature_control_file(pcms); > + > + if (mc->max_cpus > 255) { > + boot_cpus = cpu_to_le16(boot_cpus); > + fw_cfg_add_file(pcms->fw_cfg, "etc/boot-cpus", &boot_cpus, > + sizeof(boot_cpus)); > + } > } > } > > -- > 2.7.4
On Sun, 7 Aug 2016 09:02:33 +0300 "Michael S. Tsirkin" <mst@redhat.com> wrote: > On Fri, Aug 05, 2016 at 11:46:15AM +0200, Igor Mammedov wrote: > > Currently firmware uses 1 byte at 0x5F offset in RTC CMOS > > to get number of CPUs present at boot. However 1 byte is > > not enough to handle more than 255 CPUs. So add a new > > fw_cfg file that would allow QEMU to tell it. > > For compat reasons add file only for machine types that > > support more than 255 CPUs. > > > > Signed-off-by: Igor Mammedov <imammedo@redhat.com> > > Do we really need this? Why differentiate between boot > cpus and others? How about reusing the hotplug > register, such that it looks just as if all CPUs > were just added by hotplug? We could hijack cpu hotplug registers or even better extend it with new command, like GET_PRESENT_CPUS_COUNT but then we would need to tell firmware where register is located which would lead to just adding other fw_cfg file with register address. So it's not better (maybe worse) than just adding etc/boot-cpus fw_cfg file. > > > --- > > hw/i386/pc.c | 12 +++++++++++- > > 1 file changed, 11 insertions(+), 1 deletion(-) > > > > diff --git a/hw/i386/pc.c b/hw/i386/pc.c > > index c2cd5bd..2b5581a 100644 > > --- a/hw/i386/pc.c > > +++ b/hw/i386/pc.c > > @@ -1235,9 +1235,11 @@ void pc_machine_done(Notifier *notifier, void *data) > > PCMachineState *pcms = container_of(notifier, > > PCMachineState, machine_done); > > PCIBus *bus = pcms->bus; > > + static uint16_t boot_cpus; > > > > /* set the number of CPUs */ > > - rtc_set_memory(pcms->rtc, 0x5f, pc_present_cpus_count(pcms) - 1); > > + boot_cpus = pc_present_cpus_count(pcms); > > + rtc_set_memory(pcms->rtc, 0x5f, boot_cpus - 1); > > > > if (bus) { > > int extra_hosts = 0; > > @@ -1258,8 +1260,16 @@ void pc_machine_done(Notifier *notifier, void *data) > > > > acpi_setup(); > > if (pcms->fw_cfg) { > > + MachineClass *mc = MACHINE_GET_CLASS(pcms); > > + > > pc_build_smbios(pcms->fw_cfg); > > pc_build_feature_control_file(pcms); > > + > > + if (mc->max_cpus > 255) { > > + boot_cpus = cpu_to_le16(boot_cpus); > > + fw_cfg_add_file(pcms->fw_cfg, "etc/boot-cpus", &boot_cpus, > > + sizeof(boot_cpus)); > > + } > > } > > } > > > > -- > > 2.7.4
diff --git a/hw/i386/pc.c b/hw/i386/pc.c index c2cd5bd..2b5581a 100644 --- a/hw/i386/pc.c +++ b/hw/i386/pc.c @@ -1235,9 +1235,11 @@ void pc_machine_done(Notifier *notifier, void *data) PCMachineState *pcms = container_of(notifier, PCMachineState, machine_done); PCIBus *bus = pcms->bus; + static uint16_t boot_cpus; /* set the number of CPUs */ - rtc_set_memory(pcms->rtc, 0x5f, pc_present_cpus_count(pcms) - 1); + boot_cpus = pc_present_cpus_count(pcms); + rtc_set_memory(pcms->rtc, 0x5f, boot_cpus - 1); if (bus) { int extra_hosts = 0; @@ -1258,8 +1260,16 @@ void pc_machine_done(Notifier *notifier, void *data) acpi_setup(); if (pcms->fw_cfg) { + MachineClass *mc = MACHINE_GET_CLASS(pcms); + pc_build_smbios(pcms->fw_cfg); pc_build_feature_control_file(pcms); + + if (mc->max_cpus > 255) { + boot_cpus = cpu_to_le16(boot_cpus); + fw_cfg_add_file(pcms->fw_cfg, "etc/boot-cpus", &boot_cpus, + sizeof(boot_cpus)); + } } }
Currently firmware uses 1 byte at 0x5F offset in RTC CMOS to get number of CPUs present at boot. However 1 byte is not enough to handle more than 255 CPUs. So add a new fw_cfg file that would allow QEMU to tell it. For compat reasons add file only for machine types that support more than 255 CPUs. Signed-off-by: Igor Mammedov <imammedo@redhat.com> --- hw/i386/pc.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-)