[Qemu-devel] [patch 1/2] Introduce -maxcpus flag to QEMU and pass the value to the BIOS through FW_CFG.

[Jes Sorensen]

Follow on patch will use it to determine the size of the MADT and
other BIOS tables.

Signed-off-by: Jes Sorensen <address@hidden>

---
 hw/fw_cfg.c     |    1 +
 hw/fw_cfg.h     |    1 +
 qemu-options.hx |    9 +++++++++
 sysemu.h        |    1 +
 vl.c            |    8 ++++++++
 5 files changed, 20 insertions(+)

Index: qemu/hw/fw_cfg.c
===================================================================
--- qemu.orig/hw/fw_cfg.c
+++ qemu/hw/fw_cfg.c
@@ -279,6 +279,7 @@ void *fw_cfg_init(uint32_t ctl_port, uin
     fw_cfg_add_bytes(s, FW_CFG_UUID, qemu_uuid, 16);
     fw_cfg_add_i16(s, FW_CFG_NOGRAPHIC, (uint16_t)(display_type == 
DT_NOGRAPHIC));
     fw_cfg_add_i16(s, FW_CFG_NB_CPUS, (uint16_t)smp_cpus);
+    fw_cfg_add_i16(s, FW_CFG_MAX_CPUS, (uint16_t)max_cpus);
 
     register_savevm("fw_cfg", -1, 1, fw_cfg_save, fw_cfg_load, s);
     qemu_register_reset(fw_cfg_reset, 0, s);
Index: qemu/hw/fw_cfg.h
===================================================================
--- qemu.orig/hw/fw_cfg.h
+++ qemu/hw/fw_cfg.h
@@ -15,6 +15,7 @@
 #define FW_CFG_INITRD_SIZE      0x0b
 #define FW_CFG_BOOT_DEVICE      0x0c
 #define FW_CFG_NUMA             0x0d
+#define FW_CFG_MAX_CPUS         0x0e
 #define FW_CFG_MAX_ENTRY        0x10
 
 #define FW_CFG_WRITE_CHANNEL    0x4000
Index: qemu/qemu-options.hx
===================================================================
--- qemu.orig/qemu-options.hx
+++ qemu/qemu-options.hx
@@ -47,6 +47,15 @@ CPUs are supported. On Sparc32 target, L
 to 4.
 ETEXI
 
+DEF("maxcpus", HAS_ARG, QEMU_OPTION_maxcpus,
+    "-maxcpus n      set maximum number of possibly CPUs to 'n'\n")
+STEXI
address@hidden -maxcpus @var{n}
+Set the maximum number of possible CPUs to @var(n). @var(n) has to be
+bigger or equal to the value of -smp. If @var(n) is equal to -smp,
+there will be no space for hotplug cpus to be added later.
+ETEXI
+
 DEF("numa", HAS_ARG, QEMU_OPTION_numa,
     "-numa node[,mem=size][,cpus=cpu[-cpu]][,nodeid=node]\n")
 STEXI
Index: qemu/sysemu.h
===================================================================
--- qemu.orig/sysemu.h
+++ qemu/sysemu.h
@@ -118,6 +118,7 @@ extern int alt_grab;
 extern int usb_enabled;
 extern int no_virtio_balloon;
 extern int smp_cpus;
+extern int max_cpus;
 extern int cursor_hide;
 extern int graphic_rotate;
 extern int no_quit;
Index: qemu/vl.c
===================================================================
--- qemu.orig/vl.c
+++ qemu/vl.c
@@ -241,6 +241,7 @@ int rtc_td_hack = 0;
 int usb_enabled = 0;
 int singlestep = 0;
 int smp_cpus = 1;
+int max_cpus = 16;
 const char *vnc_display;
 int acpi_enabled = 1;
 int no_hpet = 0;
@@ -5556,6 +5557,13 @@ int main(int argc, char **argv, char **e
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_maxcpus:
+                max_cpus = atoi(optarg);
+                if ((max_cpus < 1) || (max_cpus > machine->max_cpus)) {
+                    fprintf(stderr, "Invalid number of CPUs\n");
+                    exit(1);
+                }
+                break;
            case QEMU_OPTION_vnc:
                 display_type = DT_VNC;
                vnc_display = optarg;