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Re: [Qemu-devel] [PATCH 2/3] hw/misc: New "unimplemented" sysbus device
From: |
Alex Bennée |
Subject: |
Re: [Qemu-devel] [PATCH 2/3] hw/misc: New "unimplemented" sysbus device |
Date: |
Fri, 27 Jan 2017 14:33:05 +0000 |
User-agent: |
mu4e 0.9.19; emacs 25.1.91.4 |
Peter Maydell <address@hidden> writes:
> Create a new "unimplemented" sysbus device, which simply accepts
> all read and write accesses, and implements them as read-as-zero,
> write-ignored, with logging of the access as LOG_UNIMP.
>
> This is useful for stubbing out bits of an SoC or board model
> which haven't been written yet.
>
> Signed-off-by: Peter Maydell <address@hidden>
This looks good:
Reviewed-by: Alex Bennée <address@hidden>
Is there any millage at being able to define areas on the command line
or would we expect every usage of this to be from a board file in the
source?
It would be useful to link to this somewhere from the docs/wiki as a
good example of a modern QDEV device boilerplate. It would make a change
from telling people to "find a recent device and use it as a template"
on IRC ;-)
Paolo,
Would this be in docs/ or on somewhere else?
> ---
> hw/misc/Makefile.objs | 2 +
> include/hw/misc/unimp.h | 39 ++++++++++++++++++
> hw/misc/unimp.c | 107
> ++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 148 insertions(+)
> create mode 100644 include/hw/misc/unimp.h
> create mode 100644 hw/misc/unimp.c
>
> diff --git a/hw/misc/Makefile.objs b/hw/misc/Makefile.objs
> index 1a89615..898e4cc 100644
> --- a/hw/misc/Makefile.objs
> +++ b/hw/misc/Makefile.objs
> @@ -6,6 +6,8 @@ common-obj-$(CONFIG_SGA) += sga.o
> common-obj-$(CONFIG_ISA_TESTDEV) += pc-testdev.o
> common-obj-$(CONFIG_PCI_TESTDEV) += pci-testdev.o
>
> +common-obj-y += unimp.o
> +
> obj-$(CONFIG_VMPORT) += vmport.o
>
> # ARM devices
> diff --git a/include/hw/misc/unimp.h b/include/hw/misc/unimp.h
> new file mode 100644
> index 0000000..3462d85
> --- /dev/null
> +++ b/include/hw/misc/unimp.h
> @@ -0,0 +1,39 @@
> +/*
> + * "Unimplemented" device
> + *
> + * Copyright Linaro Limited, 2017
> + * Written by Peter Maydell
> + */
> +
> +#ifndef HW_MISC_UNIMP_H
> +#define HW_MISC_UNIMP_H
> +
> +#define TYPE_UNIMPLEMENTED_DEVICE "unimplemented-device"
> +
> +/**
> + * create_unimplemented_device: create and map a dummy device
> + * @name: name of the device for debug logging
> + * @base: base address of the device's MMIO region
> + * @size: size of the device's MMIO region
> + *
> + * This utility function creates and maps an instance of
> unimplemented-device,
> + * which is a dummy device which simply logs all guest accesses to
> + * it via the qemu_log LOG_UNIMP debug log.
> + * The device is mapped at priority -1000, which means that you can
> + * use it to cover a large region and then map other devices on top of it
> + * if necessary.
> + */
> +static inline void create_unimplemented_device(const char *name,
> + hwaddr base,
> + hwaddr size)
> +{
> + DeviceState *dev = qdev_create(NULL, TYPE_UNIMPLEMENTED_DEVICE);
> +
> + qdev_prop_set_string(dev, "name", name);
> + qdev_prop_set_uint64(dev, "size", size);
> + qdev_init_nofail(dev);
> +
> + sysbus_mmio_map_overlap(SYS_BUS_DEVICE(dev), 0, base, -1000);
> +}
> +
> +#endif
> diff --git a/hw/misc/unimp.c b/hw/misc/unimp.c
> new file mode 100644
> index 0000000..bcbb585
> --- /dev/null
> +++ b/hw/misc/unimp.c
> @@ -0,0 +1,107 @@
> +/* "Unimplemented" device
> + *
> + * This is a dummy device which accepts and logs all accesses.
> + * It's useful for stubbing out regions of an SoC or board
> + * map which correspond to devices that have not yet been
> + * implemented. This is often sufficient to placate initial
> + * guest device driver probing such that the system will
> + * come up.
> + *
> + * Copyright Linaro Limited, 2017
> + * Written by Peter Maydell
> + */
> +
> +#include "qemu/osdep.h"
> +#include "hw/hw.h"
> +#include "hw/sysbus.h"
> +#include "hw/misc/unimp.h"
> +#include "qemu/log.h"
> +#include "qapi/error.h"
> +
> +#define UNIMPLEMENTED_DEVICE(obj) \
> + OBJECT_CHECK(UnimplementedDeviceState, (obj), TYPE_UNIMPLEMENTED_DEVICE)
> +
> +typedef struct {
> + SysBusDevice parent_obj;
> + MemoryRegion iomem;
> + char *name;
> + uint64_t size;
> +} UnimplementedDeviceState;
> +
> +static uint64_t unimp_read(void *opaque, hwaddr offset, unsigned size)
> +{
> + UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);
> +
> + qemu_log_mask(LOG_UNIMP, "%s: unimplemented device read "
> + "(size %d, offset 0x%" HWADDR_PRIx ")\n",
> + s->name, size, offset);
> + return 0;
> +}
> +
> +static void unimp_write(void *opaque, hwaddr offset,
> + uint64_t value, unsigned size)
> +{
> + UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(opaque);
> +
> + qemu_log_mask(LOG_UNIMP, "%s: unimplemented device write "
> + "(size %d, value 0x%" PRIx64
> + ", offset 0x%" HWADDR_PRIx ")\n",
> + s->name, size, value, offset);
> +}
> +
> +static const MemoryRegionOps unimp_ops = {
> + .read = unimp_read,
> + .write = unimp_write,
> + .impl.min_access_size = 1,
> + .impl.max_access_size = 8,
> + .valid.min_access_size = 1,
> + .valid.max_access_size = 8,
> + .endianness = DEVICE_NATIVE_ENDIAN,
> +};
> +
> +static void unimp_realize(DeviceState *dev, Error **errp)
> +{
> + UnimplementedDeviceState *s = UNIMPLEMENTED_DEVICE(dev);
> +
> + if (s->size == 0) {
> + error_setg(errp, "property 'size' not specified or zero");
> + return;
> + }
> +
> + if (s->name == NULL) {
> + error_setg(errp, "property 'name' not specified");
> + return;
> + }
> +
> + memory_region_init_io(&s->iomem, OBJECT(s), &unimp_ops, s,
> + s->name, s->size);
> + sysbus_init_mmio(SYS_BUS_DEVICE(s), &s->iomem);
> +}
> +
> +static Property unimp_properties[] = {
> + DEFINE_PROP_UINT64("size", UnimplementedDeviceState, size, 0),
> + DEFINE_PROP_STRING("name", UnimplementedDeviceState, name),
> + DEFINE_PROP_END_OF_LIST(),
> +};
> +
> +static void unimp_class_init(ObjectClass *klass, void *data)
> +{
> + DeviceClass *dc = DEVICE_CLASS(klass);
> +
> + dc->realize = unimp_realize;
> + dc->props = unimp_properties;
> +}
> +
> +static const TypeInfo unimp_info = {
> + .name = TYPE_UNIMPLEMENTED_DEVICE,
> + .parent = TYPE_SYS_BUS_DEVICE,
> + .instance_size = sizeof(UnimplementedDeviceState),
> + .class_init = unimp_class_init,
> +};
> +
> +static void unimp_register_types(void)
> +{
> + type_register_static(&unimp_info);
> +}
> +
> +type_init(unimp_register_types)
--
Alex Bennée