hw/core/null-machine: Add the possibility to instantiate a CPU and RAM

Sometimes it is useful to have just a machine with CPU and RAM, without
any further hardware in it, e.g. if you just want to do some instruction
debugging for TCG with a remote GDB attached to QEMU, or run some embedded
code with the "-semihosting" QEMU parameter. qemu-system-m68k already
features a "dummy" machine, and xtensa a "sim" machine for exactly this
purpose.
All target architectures have nowadays also a "none" machine, which would
be a perfect match for this, too - but it currently does not allow to add
CPU and RAM yet. Thus let's add these possibilities in a generic way to the
"none" machine, too, so that we hopefully do not need additional "dummy"
machines in the future anymore (and maybe can also get rid of the already
existing "dummy"/"sim" machines one day).
Note that the default behaviour of the "none" machine is not changed, i.e.
no CPU and no RAM is instantiated by default. You have explicitely got to
specify the CPU model with "-cpu" and the amount of RAM with "-m" to get
these new features.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Message-Id: <1484743490-24721-1-git-send-email-thuth@redhat.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@xilinx.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>

diff --git a/hw/core/Makefile.objs b/hw/core/Makefile.objs
index 833fd4689730b3c365154e694b78d4092b0a98b8..7f8c9dc65961515dffd165b4b3c0f97b7a61d5d4 100644 (file)
--- a/hw/core/Makefile.objs
+++ b/hw/core/Makefile.objs
@@ -12,7 +12,6 @@ common-obj-$(CONFIG_XILINX_AXI) += stream.o
 common-obj-$(CONFIG_PTIMER) += ptimer.o
 common-obj-$(CONFIG_SOFTMMU) += sysbus.o
 common-obj-$(CONFIG_SOFTMMU) += machine.o
-common-obj-$(CONFIG_SOFTMMU) += null-machine.o
 common-obj-$(CONFIG_SOFTMMU) += loader.o
 common-obj-$(CONFIG_SOFTMMU) += qdev-properties-system.o
 common-obj-$(CONFIG_SOFTMMU) += register.o
@@ -20,3 +19,4 @@ common-obj-$(CONFIG_SOFTMMU) += or-irq.o
 common-obj-$(CONFIG_PLATFORM_BUS) += platform-bus.o
 
 obj-$(CONFIG_SOFTMMU) += generic-loader.o
+obj-$(CONFIG_SOFTMMU) += null-machine.o

diff --git a/hw/core/null-machine.c b/hw/core/null-machine.c
index 0351ba7828255cf3bc366fce2bed0ba458f4429f..27c8369b57cccbc0b0d3c2680ef9b141d6070295 100644 (file)
--- a/hw/core/null-machine.c
+++ b/hw/core/null-machine.c
@@ -13,18 +13,41 @@
 
 #include "qemu/osdep.h"
 #include "qemu-common.h"
+#include "qemu/error-report.h"
 #include "hw/hw.h"
 #include "hw/boards.h"
+#include "sysemu/sysemu.h"
+#include "exec/address-spaces.h"
+#include "cpu.h"
 
-static void machine_none_init(MachineState *machine)
+static void machine_none_init(MachineState *mch)
 {
+    CPUState *cpu = NULL;
+
+    /* Initialize CPU (if a model has been specified) */
+    if (mch->cpu_model) {
+        cpu = cpu_init(mch->cpu_model);
+        if (!cpu) {
+            error_report("Unable to initialize CPU");
+            exit(1);
+        }
+    }
+
+    /* RAM at address zero */
+    if (mch->ram_size) {
+        MemoryRegion *ram = g_new(MemoryRegion, 1);
+
+        memory_region_allocate_system_memory(ram, NULL, "ram", mch->ram_size);
+        memory_region_add_subregion(get_system_memory(), 0, ram);
+    }
 }
 
 static void machine_none_machine_init(MachineClass *mc)
 {
     mc->desc = "empty machine";
     mc->init = machine_none_init;
-    mc->max_cpus = 0;
+    mc->max_cpus = 1;
+    mc->default_ram_size = 0;
 }
 
 DEFINE_MACHINE("none", machine_none_machine_init)