通过virt-install 创建虚拟机时qemu对vcpu和ram的限制

通过virt-install 命令创建虚拟机的时候会调用到qemu/hw/arm/virt.c 中的machvirt_machine_initstatic const TypeInfo virt_machine_info = {    .name          = TYPE_VIRT_MACHINE,    .parent        = TYPE_MACHINE,    .abstract      = true,    .instance_size = sizeof(VirtMachineState),    .class_size    = sizeof(VirtMachineClass),    .class_init    = virt_machine_class_init,};static void machvirt_machine_init(void){    type_register_static(&virt_machine_info);}这里我们重点看virt_machine_class_init->machvirt_initstatic void machvirt_init(MachineState *machine){//下面这段code中会对要创建虚拟机的vcpu的个数和ram的size检查    if (gic_version == 3) {        virt_max_cpus = vbi->memmap[VIRT_GIC_REDIST].size / 0x20000;        clustersz = GICV3_TARGETLIST_BITS;    } else {        virt_max_cpus = GIC_NCPU;        clustersz = GIC_TARGETLIST_BITS;    }    if (max_cpus > virt_max_cpus) {        error_report("Number of SMP CPUs requested (%d) exceeds max CPUs "                     "supported by machine 'mach-virt' (%d)",                     max_cpus, virt_max_cpus);        exit(1);    }    vbi->smp_cpus = smp_cpus;    if (machine->ram_size > vbi->memmap[VIRT_MEM].size) {        error_report("mach-virt: cannot model more than %dGB RAM", RAMLIMIT_GB);        exit(1);    } }这里加入gic_version 不等于3的话，则vcpu的个数不能超过virt_max_cpus = GIC_NCPU;。这里的#define GIC_NCPU 8从下面这个秒钟可以看到memory最大不能超过RAMLIMIT_BYTES，也就是256GB#define RAMLIMIT_GB 255#define RAMLIMIT_BYTES (RAMLIMIT_GB * 1024ULL * 1024 * 1024)static const MemMapEntry a15memmap[] = {    [VIRT_MEM] =                { 0x40000000, RAMLIMIT_BYTES },    /* Second PCIe window, 512GB wide at the 512GB boundary */    [VIRT_PCIE_MMIO_HIGH] =   { 0x8000000000ULL, 0x8000000000ULL },};