[v2] kvm/openpic: in-kernel mpic support

Enables support for the in-kernel MPIC that thas been merged into the
KVM next branch.  This includes irqfd/KVM_IRQ_LINE support from Alex
Graf (along with some other improvements).

Note from Alex regarding kvm_irqchip_create():

  On x86, one would call kvm_irqchip_create() to initialize an
  in-kernel interrupt controller.  That function then goes ahead and
  initializes global capability variables as well as the default irq
  routing table.

  On ppc, we can't call kvm_irqchip_create() because we can have
  different types of interrupt controllers.  So we want to do all the
  things that function would do for us in the in-kernel device init
  handler.

Signed-off-by: Scott Wood <scottwood@freescale.com>
---
v2: fix "llx" -> PRI_x64, and remove some broken leftover code
involving reg_base.
---
 default-configs/ppc-softmmu.mak   |    1 +
 default-configs/ppc64-softmmu.mak |    1 +
 hw/intc/Makefile.objs             |    1 +
 hw/intc/openpic_kvm.c             |  250 +++++++++++++++++++++++++++++++++++++
 hw/ppc/e500.c                     |   79 +++++++++++-
 include/hw/ppc/openpic.h          |    2 +-
 6 files changed, 328 insertions(+), 6 deletions(-)
 create mode 100644 hw/intc/openpic_kvm.c

On 12.06.2013, at 22:32, Scott Wood wrote:

> Enables support for the in-kernel MPIC that thas been merged into the
> KVM next branch.  This includes irqfd/KVM_IRQ_LINE support from Alex
> Graf (along with some other improvements).
> 
> Note from Alex regarding kvm_irqchip_create():
> 
>  On x86, one would call kvm_irqchip_create() to initialize an
>  in-kernel interrupt controller.  That function then goes ahead and
>  initializes global capability variables as well as the default irq
>  routing table.
> 
>  On ppc, we can't call kvm_irqchip_create() because we can have
>  different types of interrupt controllers.  So we want to do all the
>  things that function would do for us in the in-kernel device init
>  handler.
> 
> Signed-off-by: Scott Wood <scottwood@freescale.com>

Thanks, applied to ppc-next.


Alex

Am 12.06.2013 22:32, schrieb Scott Wood:
> Enables support for the in-kernel MPIC that thas been merged into the
> KVM next branch.  This includes irqfd/KVM_IRQ_LINE support from Alex
> Graf (along with some other improvements).
> 
> Note from Alex regarding kvm_irqchip_create():
> 
>   On x86, one would call kvm_irqchip_create() to initialize an
>   in-kernel interrupt controller.  That function then goes ahead and
>   initializes global capability variables as well as the default irq
>   routing table.
> 
>   On ppc, we can't call kvm_irqchip_create() because we can have
>   different types of interrupt controllers.  So we want to do all the
>   things that function would do for us in the in-kernel device init
>   handler.
> 
> Signed-off-by: Scott Wood <scottwood@freescale.com>
> ---
> v2: fix "llx" -> PRI_x64, and remove some broken leftover code
> involving reg_base.
> ---
>  default-configs/ppc-softmmu.mak   |    1 +
>  default-configs/ppc64-softmmu.mak |    1 +
>  hw/intc/Makefile.objs             |    1 +
>  hw/intc/openpic_kvm.c             |  250 +++++++++++++++++++++++++++++++++++++
>  hw/ppc/e500.c                     |   79 +++++++++++-
>  include/hw/ppc/openpic.h          |    2 +-
>  6 files changed, 328 insertions(+), 6 deletions(-)
>  create mode 100644 hw/intc/openpic_kvm.c
> 
> diff --git a/default-configs/ppc-softmmu.mak b/default-configs/ppc-softmmu.mak
> index cc3587f..63255dc 100644
> --- a/default-configs/ppc-softmmu.mak
> +++ b/default-configs/ppc-softmmu.mak
> @@ -43,5 +43,6 @@ CONFIG_XILINX=y
>  CONFIG_XILINX_ETHLITE=y
>  CONFIG_OPENPIC=y
>  CONFIG_E500=$(CONFIG_FDT)
> +CONFIG_OPENPIC_KVM=$(and $(CONFIG_E500),$(CONFIG_KVM))
>  # For PReP
>  CONFIG_MC146818RTC=y
> diff --git a/default-configs/ppc64-softmmu.mak b/default-configs/ppc64-softmmu.mak
> index 884ea8a..e3c0c68 100644
> --- a/default-configs/ppc64-softmmu.mak
> +++ b/default-configs/ppc64-softmmu.mak
> @@ -44,6 +44,7 @@ CONFIG_XILINX_ETHLITE=y
>  CONFIG_OPENPIC=y
>  CONFIG_PSERIES=$(CONFIG_FDT)
>  CONFIG_E500=$(CONFIG_FDT)
> +CONFIG_OPENPIC_KVM=$(and $(CONFIG_E500),$(CONFIG_KVM))
>  # For pSeries
>  CONFIG_PCI_HOTPLUG=y
>  # For PReP
> diff --git a/hw/intc/Makefile.objs b/hw/intc/Makefile.objs
> index 718d97a..837ef19 100644
> --- a/hw/intc/Makefile.objs
> +++ b/hw/intc/Makefile.objs
> @@ -20,4 +20,5 @@ obj-$(CONFIG_GRLIB) += grlib_irqmp.o
>  obj-$(CONFIG_IOAPIC) += ioapic.o
>  obj-$(CONFIG_OMAP) += omap_intc.o
>  obj-$(CONFIG_OPENPIC) += openpic.o
> +obj-$(CONFIG_OPENPIC_KVM) += openpic_kvm.o
>  obj-$(CONFIG_SH4) += sh_intc.o
> diff --git a/hw/intc/openpic_kvm.c b/hw/intc/openpic_kvm.c
> new file mode 100644
> index 0000000..809b34b
> --- /dev/null
> +++ b/hw/intc/openpic_kvm.c
> @@ -0,0 +1,250 @@
> +/*
> + * KVM in-kernel OpenPIC
> + *
> + * Copyright 2013 Freescale Semiconductor, Inc.
> + *
> + * Permission is hereby granted, free of charge, to any person obtaining a copy
> + * of this software and associated documentation files (the "Software"), to deal
> + * in the Software without restriction, including without limitation the rights
> + * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
> + * copies of the Software, and to permit persons to whom the Software is
> + * furnished to do so, subject to the following conditions:
> + *
> + * The above copyright notice and this permission notice shall be included in
> + * all copies or substantial portions of the Software.
> + *
> + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
> + * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
> + * THE SOFTWARE.
> + */
> +
> +#include <sys/ioctl.h>
> +#include "exec/address-spaces.h"
> +#include "hw/hw.h"
> +#include "hw/ppc/openpic.h"
> +#include "hw/pci/msi.h"
> +#include "hw/sysbus.h"
> +#include "sysemu/kvm.h"
> +#include "qemu/log.h"
> +
> +typedef struct KVMOpenPICState {
> +    SysBusDevice busdev;

SysBusDevice parent_obj; please!

http://wiki.qemu.org/QOMConventions

> +    MemoryRegion mem;
> +    MemoryListener mem_listener;
> +    uint32_t fd;
> +    uint32_t model;
> +} KVMOpenPICState;
> +
> +static void kvm_openpic_set_irq(void *opaque, int n_IRQ, int level)
> +{
> +    kvm_set_irq(kvm_state, n_IRQ, level);
> +}
> +
> +static void kvm_openpic_reset(DeviceState *d)
> +{
> +    qemu_log_mask(LOG_UNIMP, "%s: unimplemented\n", __func__);
> +}
> +
> +static void kvm_openpic_write(void *opaque, hwaddr addr, uint64_t val,
> +                              unsigned size)
> +{
> +    KVMOpenPICState *opp = opaque;
> +    struct kvm_device_attr attr;
> +    uint32_t val32 = val;
> +    int ret;
> +
> +    attr.group = KVM_DEV_MPIC_GRP_REGISTER;
> +    attr.attr = addr;
> +    attr.addr = (uint64_t)(unsigned long)&val32;
> +
> +    ret = ioctl(opp->fd, KVM_SET_DEVICE_ATTR, &attr);
> +    if (ret < 0) {
> +        qemu_log_mask(LOG_UNIMP, "%s: %s %" PRIx64 "\n", __func__,
> +                      strerror(errno), attr.attr);
> +    }
> +}
> +
> +static uint64_t kvm_openpic_read(void *opaque, hwaddr addr, unsigned size)
> +{
> +    KVMOpenPICState *opp = opaque;
> +    struct kvm_device_attr attr;
> +    uint32_t val = 0xdeadbeef;
> +    int ret;
> +
> +    attr.group = KVM_DEV_MPIC_GRP_REGISTER;
> +    attr.attr = addr;
> +    attr.addr = (uint64_t)(unsigned long)&val;
> +
> +    ret = ioctl(opp->fd, KVM_GET_DEVICE_ATTR, &attr);
> +    if (ret < 0) {
> +        qemu_log_mask(LOG_UNIMP, "%s: %s %" PRIx64 "\n", __func__,
> +                      strerror(errno), attr.attr);
> +        return 0;
> +    }
> +
> +    return val;
> +}
> +
> +static const MemoryRegionOps kvm_openpic_mem_ops = {
> +    .write = kvm_openpic_write,
> +    .read  = kvm_openpic_read,
> +    .endianness = DEVICE_BIG_ENDIAN,
> +    .impl = {
> +        .min_access_size = 4,
> +        .max_access_size = 4,
> +    },
> +};
> +
> +static void kvm_openpic_region_add(MemoryListener *listener,
> +                                   MemoryRegionSection *section)
> +{
> +    KVMOpenPICState *opp = container_of(listener, KVMOpenPICState,
> +                                        mem_listener);
> +    struct kvm_device_attr attr;
> +    uint64_t reg_base;
> +    int ret;
> +
> +    if (section->address_space != &address_space_memory) {
> +        abort();
> +    }
> +
> +    reg_base = section->offset_within_address_space;
> +
> +    attr.group = KVM_DEV_MPIC_GRP_MISC;
> +    attr.attr = KVM_DEV_MPIC_BASE_ADDR;
> +    attr.addr = (uint64_t)(unsigned long)&reg_base;
> +
> +    ret = ioctl(opp->fd, KVM_SET_DEVICE_ATTR, &attr);
> +    if (ret < 0) {
> +        fprintf(stderr, "%s: %s %" PRIx64 "\n", __func__,
> +                strerror(errno), reg_base);
> +    }
> +}
> +
> +static void kvm_openpic_region_del(MemoryListener *listener,
> +                                   MemoryRegionSection *section)
> +{
> +    KVMOpenPICState *opp = container_of(listener, KVMOpenPICState,
> +                                        mem_listener);
> +    struct kvm_device_attr attr;
> +    uint64_t reg_base = 0;
> +    int ret;
> +
> +    attr.group = KVM_DEV_MPIC_GRP_MISC;
> +    attr.attr = KVM_DEV_MPIC_BASE_ADDR;
> +    attr.addr = (uint64_t)(unsigned long)&reg_base;
> +
> +    ret = ioctl(opp->fd, KVM_SET_DEVICE_ATTR, &attr);
> +    if (ret < 0) {
> +        fprintf(stderr, "%s: %s %" PRIx64 "\n", __func__,
> +                strerror(errno), reg_base);
> +    }
> +}
> +
> +static int kvm_openpic_init(SysBusDevice *dev)

Please make this instance_init + realize functions - "dev" should rather
be reserved for DeviceState.

> +{
> +    KVMState *s = kvm_state;
> +    KVMOpenPICState *opp = FROM_SYSBUS(typeof(*opp), dev);

NACK, please introduce your own KVM_OPENPIC(obj) cast macro instead for
new devices - has been a topic for several weeks and months now.

> +    int kvm_openpic_model;
> +    struct kvm_create_device cd = {0};
> +    int ret, i;
> +
> +    if (!kvm_check_extension(s, KVM_CAP_DEVICE_CTRL)) {
> +        return -EINVAL;
> +    }
> +
> +    switch (opp->model) {
> +    case OPENPIC_MODEL_FSL_MPIC_20:
> +        kvm_openpic_model = KVM_DEV_TYPE_FSL_MPIC_20;
> +        break;
> +
> +    case OPENPIC_MODEL_FSL_MPIC_42:
> +        kvm_openpic_model = KVM_DEV_TYPE_FSL_MPIC_42;
> +        break;
> +
> +    default:
> +        return -EINVAL;
> +    }

If there's only two supported enum-style options, why not make it two
devices with the value set as a class field?

> +
> +    cd.type = kvm_openpic_model;
> +    ret = kvm_vm_ioctl(s, KVM_CREATE_DEVICE, &cd);
> +    if (ret < 0) {
> +        qemu_log_mask(LOG_UNIMP, "%s: can't create device %d: %s\n",
> +                      __func__, cd.type, strerror(errno));
> +        return -EINVAL;
> +    }
> +    opp->fd = cd.fd;
> +
> +    memory_region_init_io(&opp->mem, &kvm_openpic_mem_ops, opp,
> +                          "kvm-openpic", 0x40000);
> +
> +    sysbus_init_mmio(dev, &opp->mem);
> +    qdev_init_gpio_in(&dev->qdev, kvm_openpic_set_irq, OPENPIC_MAX_IRQ);
> +
> +    opp->mem_listener.region_add = kvm_openpic_region_add;
> +    opp->mem_listener.region_add = kvm_openpic_region_del;
> +    memory_listener_register(&opp->mem_listener, &address_space_memory);
> +
> +    /* indicate pic capabilities */
> +    msi_supported = true;
> +    kvm_kernel_irqchip = true;
> +    kvm_async_interrupts_allowed = true;
> +
> +    /* set up irq routing */
> +    kvm_init_irq_routing(kvm_state);
> +    for (i = 0; i < 256; ++i) {
> +        kvm_irqchip_add_irq_route(kvm_state, i, 0, i);
> +    }
> +
> +    kvm_irqfds_allowed = true;
> +    kvm_msi_via_irqfd_allowed = true;
> +    kvm_gsi_routing_allowed = true;
> +
> +    return 0;
> +}
> +
> +int kvm_openpic_connect_vcpu(DeviceState *d, CPUState *cs)
> +{
> +    KVMOpenPICState *opp = FROM_SYSBUS(typeof(*opp), SYS_BUS_DEVICE(d));

KVM_OPENPIC(d)

> +    struct kvm_enable_cap encap = {};
> +
> +    encap.cap = KVM_CAP_IRQ_MPIC;
> +    encap.args[0] = opp->fd;
> +    encap.args[1] = cs->cpu_index;
> +
> +    return kvm_vcpu_ioctl(cs, KVM_ENABLE_CAP, &encap);
> +}
> +
> +static Property kvm_openpic_properties[] = {
> +    DEFINE_PROP_UINT32("model", KVMOpenPICState, model,
> +                       OPENPIC_MODEL_FSL_MPIC_20),
> +    DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void kvm_openpic_class_init(ObjectClass *klass, void *data)
> +{
> +    DeviceClass *dc = DEVICE_CLASS(klass);
> +    SysBusDeviceClass *k = SYS_BUS_DEVICE_CLASS(klass);
> +
> +    k->init = kvm_openpic_init;
> +    dc->props = kvm_openpic_properties;
> +    dc->reset = kvm_openpic_reset;
> +}
> +
> +static const TypeInfo kvm_openpic_info = {
> +    .name          = "kvm-openpic",
> +    .parent        = TYPE_SYS_BUS_DEVICE,
> +    .instance_size = sizeof(KVMOpenPICState),
> +    .class_init    = kvm_openpic_class_init,
> +};
> +
> +static void kvm_openpic_register_types(void)
> +{
> +    type_register_static(&kvm_openpic_info);
> +}
> +
> +type_init(kvm_openpic_register_types)
> diff --git a/hw/ppc/e500.c b/hw/ppc/e500.c
> index 14e0547..f790ed1 100644
> --- a/hw/ppc/e500.c
> +++ b/hw/ppc/e500.c
> @@ -448,18 +448,17 @@ static void ppce500_cpu_reset(void *opaque)
>      mmubooke_create_initial_mapping(env);
>  }
>  
> -static qemu_irq *ppce500_init_mpic(PPCE500Params *params, MemoryRegion *ccsr,
> -                                   qemu_irq **irqs)
> +static DeviceState *ppce500_init_mpic_qemu(PPCE500Params *params,
> +                                           qemu_irq **irqs)
>  {
> -    qemu_irq *mpic;
>      DeviceState *dev;
>      SysBusDevice *s;
>      int i, j, k;
>  
> -    mpic = g_new(qemu_irq, 256);
>      dev = qdev_create(NULL, "openpic");
> -    qdev_prop_set_uint32(dev, "nb_cpus", smp_cpus);
>      qdev_prop_set_uint32(dev, "model", params->mpic_version);
> +    qdev_prop_set_uint32(dev, "nb_cpus", smp_cpus);
> +
>      qdev_init_nofail(dev);
>      s = SYS_BUS_DEVICE(dev);
>  
> @@ -470,10 +469,80 @@ static qemu_irq *ppce500_init_mpic(PPCE500Params *params, MemoryRegion *ccsr,
>          }
>      }
>  
> +    return dev;
> +}
> +
> +static DeviceState *ppce500_init_mpic_kvm(PPCE500Params *params,
> +                                          qemu_irq **irqs)
> +{
> +    DeviceState *dev;
> +    CPUPPCState *env;
> +    CPUState *cs;
> +    int r;
> +
> +    dev = qdev_create(NULL, "kvm-openpic");
> +    qdev_prop_set_uint32(dev, "model", params->mpic_version);
> +
> +    r = qdev_init(dev);
> +    if (r) {
> +        return NULL;
> +    }
> +
> +    for (env = first_cpu; env != NULL; env = env->next_cpu) {
> +        cs = ENV_GET_CPU(env);
> +
> +        if (kvm_openpic_connect_vcpu(dev, cs)) {
> +            fprintf(stderr, "%s: failed to connect vcpu to irqchip\n",
> +                    __func__);
> +            abort();
> +        }
> +    }

Note: My series on the list converts first_cpu to CPUState, so this may
conflict depending on pull timing. Resolution would be s/env/cs/g.

Andreas

> +
> +    return dev;
> +}
> +
> +static qemu_irq *ppce500_init_mpic(PPCE500Params *params, MemoryRegion *ccsr,
> +                                   qemu_irq **irqs)
> +{
> +    QemuOptsList *list;
> +    qemu_irq *mpic;
> +    DeviceState *dev = NULL;
> +    SysBusDevice *s;
> +    int i;
> +
> +    mpic = g_new(qemu_irq, 256);
> +
> +    if (kvm_enabled()) {
> +        bool irqchip_allowed = true, irqchip_required = false;
> +
> +        list = qemu_find_opts("machine");
> +        if (!QTAILQ_EMPTY(&list->head)) {
> +            irqchip_allowed = qemu_opt_get_bool(QTAILQ_FIRST(&list->head),
> +                                                "kernel_irqchip", true);
> +            irqchip_required = qemu_opt_get_bool(QTAILQ_FIRST(&list->head),
> +                                                 "kernel_irqchip", false);
> +        }
> +
> +        if (irqchip_allowed) {
> +            dev = ppce500_init_mpic_kvm(params, irqs);
> +        }
> +
> +        if (irqchip_required && !dev) {
> +            fprintf(stderr, "%s: irqchip requested but unavailable\n",
> +                    __func__);
> +            abort();
> +        }
> +    }
> +
> +    if (!dev) {
> +        dev = ppce500_init_mpic_qemu(params, irqs);
> +    }
> +
>      for (i = 0; i < 256; i++) {
>          mpic[i] = qdev_get_gpio_in(dev, i);
>      }
>  
> +    s = SYS_BUS_DEVICE(dev);
>      memory_region_add_subregion(ccsr, MPC8544_MPIC_REGS_OFFSET,
>                                  s->mmio[0].memory);
>  
> diff --git a/include/hw/ppc/openpic.h b/include/hw/ppc/openpic.h
> index d873bb6..1fe4865 100644
> --- a/include/hw/ppc/openpic.h
> +++ b/include/hw/ppc/openpic.h
> @@ -24,6 +24,6 @@ enum {
>  #define OPENPIC_MAX_IRQ     (OPENPIC_MAX_SRC + OPENPIC_MAX_IPI + \
>                               OPENPIC_MAX_TMR)
>  
> -DeviceState *kvm_openpic_create(BusState *bus, int model);
> +int kvm_openpic_connect_vcpu(DeviceState *d, CPUState *cs);
>  
>  #endif /* __OPENPIC_H__ */
>

Subject is misleading: it's intc/openpic_kvm, not kvm/openpic. Alex,
please fix when squashing.

Am 12.06.2013 22:32, schrieb Scott Wood:
> Enables support for the in-kernel MPIC that thas been merged into the
> KVM next branch.  This includes irqfd/KVM_IRQ_LINE support from Alex
> Graf (along with some other improvements).
> 
> Note from Alex regarding kvm_irqchip_create():
> 
>   On x86, one would call kvm_irqchip_create() to initialize an
>   in-kernel interrupt controller.  That function then goes ahead and
>   initializes global capability variables as well as the default irq
>   routing table.
> 
>   On ppc, we can't call kvm_irqchip_create() because we can have
>   different types of interrupt controllers.  So we want to do all the
>   things that function would do for us in the in-kernel device init
>   handler.
> 
> Signed-off-by: Scott Wood <scottwood@freescale.com>
> ---
> v2: fix "llx" -> PRI_x64, and remove some broken leftover code
> involving reg_base.
> ---
>  default-configs/ppc-softmmu.mak   |    1 +
>  default-configs/ppc64-softmmu.mak |    1 +

This breaks KVM-enabled ppcemb-softmmu build with unresolved symbol
kvm_openpic_connect_vcpu() in e500.o. Fix in my patch:

http://patchwork.ozlabs.org/patch/251731/

Because intc/openpic.c gets rebuilt for each of the three ppc*-softmmu,
I added a patch to my qom-cpu-10 series to stop that for openpic. For
openpic_kvm I believe that won't be possible due to sysemu/kvm.h's
inline stubs.

Andreas

>  hw/intc/Makefile.objs             |    1 +
>  hw/intc/openpic_kvm.c             |  250 +++++++++++++++++++++++++++++++++++++
>  hw/ppc/e500.c                     |   79 +++++++++++-
>  include/hw/ppc/openpic.h          |    2 +-
>  6 files changed, 328 insertions(+), 6 deletions(-)
>  create mode 100644 hw/intc/openpic_kvm.c

On 06/16/2013 02:25:04 PM, Andreas Färber wrote:
> Subject is misleading: it's intc/openpic_kvm, not kvm/openpic. Alex,
> please fix when squashing.

I meant it as a general description of the functional area, not as a  
literal pathname.  It looks like that format is more of a Linux kernel  
thing and not used by QEMU much (if at all) -- sorry about that.   
Should have been "kvm: openpic: in-kernel mpic support".

-Scott

Am 16.06.2013 21:25, schrieb Andreas Färber:
> Am 12.06.2013 22:32, schrieb Scott Wood:
>> Enables support for the in-kernel MPIC that thas been merged into the
>> KVM next branch.  This includes irqfd/KVM_IRQ_LINE support from Alex
>> Graf (along with some other improvements).
>>
>> Note from Alex regarding kvm_irqchip_create():
>>
>>   On x86, one would call kvm_irqchip_create() to initialize an
>>   in-kernel interrupt controller.  That function then goes ahead and
>>   initializes global capability variables as well as the default irq
>>   routing table.
>>
>>   On ppc, we can't call kvm_irqchip_create() because we can have
>>   different types of interrupt controllers.  So we want to do all the
>>   things that function would do for us in the in-kernel device init
>>   handler.
>>
>> Signed-off-by: Scott Wood <scottwood@freescale.com>
[...]
>> ---
>>  default-configs/ppc-softmmu.mak   |    1 +
>>  default-configs/ppc64-softmmu.mak |    1 +
> 
> This breaks KVM-enabled ppcemb-softmmu build with unresolved symbol
> kvm_openpic_connect_vcpu() in e500.o. Fix in my patch:
> 
> http://patchwork.ozlabs.org/patch/251731/

This issue brought up an interesting question:
Why didn't the buildbots report this build breakage on ppc-next branch?

Both of us didn't see any buildbot emails for quite a while - was this
disabled for some reason?

I didn't find the answer in
https://github.com/b1-systems/buildbot/blob/master/qemu-master.cfg
but I noticed that it still has Stefan's rather than Michael's trivial
tree URL.

Looking at
http://buildbot.b1-systems.de/qemu/one_line_per_build
I see that most builders fail due to configure - which I guess points at
lack of compatible libfdt or dtc submodule.

Regards,
Andreas