qemu/hw/riscv/virt.c
Alistair Francis ceb2ffd56e
riscv: virt: Allow specifying a CPU via commandline
Signed-off-by: Alistair Francis <alistair.francis@wdc.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Signed-off-by: Palmer Dabbelt <palmer@sifive.com>
2019-05-24 12:09:23 -07:00

532 lines
21 KiB
C

/*
* QEMU RISC-V VirtIO Board
*
* Copyright (c) 2017 SiFive, Inc.
*
* RISC-V machine with 16550a UART and VirtIO MMIO
*
* This program is free software; you can redistribute it and/or modify it
* under the terms and conditions of the GNU General Public License,
* version 2 or later, as published by the Free Software Foundation.
*
* This program is distributed in the hope it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU General Public License along with
* this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "qemu/osdep.h"
#include "qemu/units.h"
#include "qemu/log.h"
#include "qemu/error-report.h"
#include "qapi/error.h"
#include "hw/hw.h"
#include "hw/boards.h"
#include "hw/loader.h"
#include "hw/sysbus.h"
#include "hw/char/serial.h"
#include "target/riscv/cpu.h"
#include "hw/riscv/riscv_hart.h"
#include "hw/riscv/sifive_plic.h"
#include "hw/riscv/sifive_clint.h"
#include "hw/riscv/sifive_test.h"
#include "hw/riscv/virt.h"
#include "chardev/char.h"
#include "sysemu/arch_init.h"
#include "sysemu/device_tree.h"
#include "exec/address-spaces.h"
#include "hw/pci/pci.h"
#include "hw/pci-host/gpex.h"
#include "elf.h"
#include <libfdt.h>
static const struct MemmapEntry {
hwaddr base;
hwaddr size;
} virt_memmap[] = {
[VIRT_DEBUG] = { 0x0, 0x100 },
[VIRT_MROM] = { 0x1000, 0x11000 },
[VIRT_TEST] = { 0x100000, 0x1000 },
[VIRT_CLINT] = { 0x2000000, 0x10000 },
[VIRT_PLIC] = { 0xc000000, 0x4000000 },
[VIRT_UART0] = { 0x10000000, 0x100 },
[VIRT_VIRTIO] = { 0x10001000, 0x1000 },
[VIRT_DRAM] = { 0x80000000, 0x0 },
[VIRT_PCIE_MMIO] = { 0x40000000, 0x40000000 },
[VIRT_PCIE_PIO] = { 0x03000000, 0x00010000 },
[VIRT_PCIE_ECAM] = { 0x30000000, 0x10000000 },
};
static target_ulong load_kernel(const char *kernel_filename)
{
uint64_t kernel_entry, kernel_high;
if (load_elf(kernel_filename, NULL, NULL, NULL,
&kernel_entry, NULL, &kernel_high,
0, EM_RISCV, 1, 0) < 0) {
error_report("could not load kernel '%s'", kernel_filename);
exit(1);
}
return kernel_entry;
}
static hwaddr load_initrd(const char *filename, uint64_t mem_size,
uint64_t kernel_entry, hwaddr *start)
{
int size;
/* We want to put the initrd far enough into RAM that when the
* kernel is uncompressed it will not clobber the initrd. However
* on boards without much RAM we must ensure that we still leave
* enough room for a decent sized initrd, and on boards with large
* amounts of RAM we must avoid the initrd being so far up in RAM
* that it is outside lowmem and inaccessible to the kernel.
* So for boards with less than 256MB of RAM we put the initrd
* halfway into RAM, and for boards with 256MB of RAM or more we put
* the initrd at 128MB.
*/
*start = kernel_entry + MIN(mem_size / 2, 128 * MiB);
size = load_ramdisk(filename, *start, mem_size - *start);
if (size == -1) {
size = load_image_targphys(filename, *start, mem_size - *start);
if (size == -1) {
error_report("could not load ramdisk '%s'", filename);
exit(1);
}
}
return *start + size;
}
static void create_pcie_irq_map(void *fdt, char *nodename,
uint32_t plic_phandle)
{
int pin, dev;
uint32_t
full_irq_map[GPEX_NUM_IRQS * GPEX_NUM_IRQS * FDT_INT_MAP_WIDTH] = {};
uint32_t *irq_map = full_irq_map;
/* This code creates a standard swizzle of interrupts such that
* each device's first interrupt is based on it's PCI_SLOT number.
* (See pci_swizzle_map_irq_fn())
*
* We only need one entry per interrupt in the table (not one per
* possible slot) seeing the interrupt-map-mask will allow the table
* to wrap to any number of devices.
*/
for (dev = 0; dev < GPEX_NUM_IRQS; dev++) {
int devfn = dev * 0x8;
for (pin = 0; pin < GPEX_NUM_IRQS; pin++) {
int irq_nr = PCIE_IRQ + ((pin + PCI_SLOT(devfn)) % GPEX_NUM_IRQS);
int i = 0;
irq_map[i] = cpu_to_be32(devfn << 8);
i += FDT_PCI_ADDR_CELLS;
irq_map[i] = cpu_to_be32(pin + 1);
i += FDT_PCI_INT_CELLS;
irq_map[i++] = cpu_to_be32(plic_phandle);
i += FDT_PLIC_ADDR_CELLS;
irq_map[i] = cpu_to_be32(irq_nr);
irq_map += FDT_INT_MAP_WIDTH;
}
}
qemu_fdt_setprop(fdt, nodename, "interrupt-map",
full_irq_map, sizeof(full_irq_map));
qemu_fdt_setprop_cells(fdt, nodename, "interrupt-map-mask",
0x1800, 0, 0, 0x7);
}
static void *create_fdt(RISCVVirtState *s, const struct MemmapEntry *memmap,
uint64_t mem_size, const char *cmdline)
{
void *fdt;
int cpu;
uint32_t *cells;
char *nodename;
uint32_t plic_phandle, phandle = 1;
int i;
fdt = s->fdt = create_device_tree(&s->fdt_size);
if (!fdt) {
error_report("create_device_tree() failed");
exit(1);
}
qemu_fdt_setprop_string(fdt, "/", "model", "riscv-virtio,qemu");
qemu_fdt_setprop_string(fdt, "/", "compatible", "riscv-virtio");
qemu_fdt_setprop_cell(fdt, "/", "#size-cells", 0x2);
qemu_fdt_setprop_cell(fdt, "/", "#address-cells", 0x2);
qemu_fdt_add_subnode(fdt, "/soc");
qemu_fdt_setprop(fdt, "/soc", "ranges", NULL, 0);
qemu_fdt_setprop_string(fdt, "/soc", "compatible", "simple-bus");
qemu_fdt_setprop_cell(fdt, "/soc", "#size-cells", 0x2);
qemu_fdt_setprop_cell(fdt, "/soc", "#address-cells", 0x2);
nodename = g_strdup_printf("/memory@%lx",
(long)memmap[VIRT_DRAM].base);
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_cells(fdt, nodename, "reg",
memmap[VIRT_DRAM].base >> 32, memmap[VIRT_DRAM].base,
mem_size >> 32, mem_size);
qemu_fdt_setprop_string(fdt, nodename, "device_type", "memory");
g_free(nodename);
qemu_fdt_add_subnode(fdt, "/cpus");
qemu_fdt_setprop_cell(fdt, "/cpus", "timebase-frequency",
SIFIVE_CLINT_TIMEBASE_FREQ);
qemu_fdt_setprop_cell(fdt, "/cpus", "#size-cells", 0x0);
qemu_fdt_setprop_cell(fdt, "/cpus", "#address-cells", 0x1);
for (cpu = s->soc.num_harts - 1; cpu >= 0; cpu--) {
int cpu_phandle = phandle++;
nodename = g_strdup_printf("/cpus/cpu@%d", cpu);
char *intc = g_strdup_printf("/cpus/cpu@%d/interrupt-controller", cpu);
char *isa = riscv_isa_string(&s->soc.harts[cpu]);
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_cell(fdt, nodename, "clock-frequency",
VIRT_CLOCK_FREQ);
qemu_fdt_setprop_string(fdt, nodename, "mmu-type", "riscv,sv48");
qemu_fdt_setprop_string(fdt, nodename, "riscv,isa", isa);
qemu_fdt_setprop_string(fdt, nodename, "compatible", "riscv");
qemu_fdt_setprop_string(fdt, nodename, "status", "okay");
qemu_fdt_setprop_cell(fdt, nodename, "reg", cpu);
qemu_fdt_setprop_string(fdt, nodename, "device_type", "cpu");
qemu_fdt_add_subnode(fdt, intc);
qemu_fdt_setprop_cell(fdt, intc, "phandle", cpu_phandle);
qemu_fdt_setprop_cell(fdt, intc, "linux,phandle", cpu_phandle);
qemu_fdt_setprop_string(fdt, intc, "compatible", "riscv,cpu-intc");
qemu_fdt_setprop(fdt, intc, "interrupt-controller", NULL, 0);
qemu_fdt_setprop_cell(fdt, intc, "#interrupt-cells", 1);
g_free(isa);
g_free(intc);
g_free(nodename);
}
cells = g_new0(uint32_t, s->soc.num_harts * 4);
for (cpu = 0; cpu < s->soc.num_harts; cpu++) {
nodename =
g_strdup_printf("/cpus/cpu@%d/interrupt-controller", cpu);
uint32_t intc_phandle = qemu_fdt_get_phandle(fdt, nodename);
cells[cpu * 4 + 0] = cpu_to_be32(intc_phandle);
cells[cpu * 4 + 1] = cpu_to_be32(IRQ_M_SOFT);
cells[cpu * 4 + 2] = cpu_to_be32(intc_phandle);
cells[cpu * 4 + 3] = cpu_to_be32(IRQ_M_TIMER);
g_free(nodename);
}
nodename = g_strdup_printf("/soc/clint@%lx",
(long)memmap[VIRT_CLINT].base);
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_string(fdt, nodename, "compatible", "riscv,clint0");
qemu_fdt_setprop_cells(fdt, nodename, "reg",
0x0, memmap[VIRT_CLINT].base,
0x0, memmap[VIRT_CLINT].size);
qemu_fdt_setprop(fdt, nodename, "interrupts-extended",
cells, s->soc.num_harts * sizeof(uint32_t) * 4);
g_free(cells);
g_free(nodename);
plic_phandle = phandle++;
cells = g_new0(uint32_t, s->soc.num_harts * 4);
for (cpu = 0; cpu < s->soc.num_harts; cpu++) {
nodename =
g_strdup_printf("/cpus/cpu@%d/interrupt-controller", cpu);
uint32_t intc_phandle = qemu_fdt_get_phandle(fdt, nodename);
cells[cpu * 4 + 0] = cpu_to_be32(intc_phandle);
cells[cpu * 4 + 1] = cpu_to_be32(IRQ_M_EXT);
cells[cpu * 4 + 2] = cpu_to_be32(intc_phandle);
cells[cpu * 4 + 3] = cpu_to_be32(IRQ_S_EXT);
g_free(nodename);
}
nodename = g_strdup_printf("/soc/interrupt-controller@%lx",
(long)memmap[VIRT_PLIC].base);
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_cells(fdt, nodename, "#address-cells",
FDT_PLIC_ADDR_CELLS);
qemu_fdt_setprop_cell(fdt, nodename, "#interrupt-cells",
FDT_PLIC_INT_CELLS);
qemu_fdt_setprop_string(fdt, nodename, "compatible", "riscv,plic0");
qemu_fdt_setprop(fdt, nodename, "interrupt-controller", NULL, 0);
qemu_fdt_setprop(fdt, nodename, "interrupts-extended",
cells, s->soc.num_harts * sizeof(uint32_t) * 4);
qemu_fdt_setprop_cells(fdt, nodename, "reg",
0x0, memmap[VIRT_PLIC].base,
0x0, memmap[VIRT_PLIC].size);
qemu_fdt_setprop_string(fdt, nodename, "reg-names", "control");
qemu_fdt_setprop_cell(fdt, nodename, "riscv,max-priority", 7);
qemu_fdt_setprop_cell(fdt, nodename, "riscv,ndev", VIRTIO_NDEV);
qemu_fdt_setprop_cells(fdt, nodename, "phandle", plic_phandle);
qemu_fdt_setprop_cells(fdt, nodename, "linux,phandle", plic_phandle);
plic_phandle = qemu_fdt_get_phandle(fdt, nodename);
g_free(cells);
g_free(nodename);
for (i = 0; i < VIRTIO_COUNT; i++) {
nodename = g_strdup_printf("/virtio_mmio@%lx",
(long)(memmap[VIRT_VIRTIO].base + i * memmap[VIRT_VIRTIO].size));
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_string(fdt, nodename, "compatible", "virtio,mmio");
qemu_fdt_setprop_cells(fdt, nodename, "reg",
0x0, memmap[VIRT_VIRTIO].base + i * memmap[VIRT_VIRTIO].size,
0x0, memmap[VIRT_VIRTIO].size);
qemu_fdt_setprop_cells(fdt, nodename, "interrupt-parent", plic_phandle);
qemu_fdt_setprop_cells(fdt, nodename, "interrupts", VIRTIO_IRQ + i);
g_free(nodename);
}
nodename = g_strdup_printf("/soc/pci@%lx",
(long) memmap[VIRT_PCIE_ECAM].base);
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_cells(fdt, nodename, "#address-cells",
FDT_PCI_ADDR_CELLS);
qemu_fdt_setprop_cells(fdt, nodename, "#interrupt-cells",
FDT_PCI_INT_CELLS);
qemu_fdt_setprop_cells(fdt, nodename, "#size-cells", 0x2);
qemu_fdt_setprop_string(fdt, nodename, "compatible",
"pci-host-ecam-generic");
qemu_fdt_setprop_string(fdt, nodename, "device_type", "pci");
qemu_fdt_setprop_cell(fdt, nodename, "linux,pci-domain", 0);
qemu_fdt_setprop_cells(fdt, nodename, "bus-range", 0,
memmap[VIRT_PCIE_ECAM].base /
PCIE_MMCFG_SIZE_MIN - 1);
qemu_fdt_setprop(fdt, nodename, "dma-coherent", NULL, 0);
qemu_fdt_setprop_cells(fdt, nodename, "reg", 0, memmap[VIRT_PCIE_ECAM].base,
0, memmap[VIRT_PCIE_ECAM].size);
qemu_fdt_setprop_sized_cells(fdt, nodename, "ranges",
1, FDT_PCI_RANGE_IOPORT, 2, 0,
2, memmap[VIRT_PCIE_PIO].base, 2, memmap[VIRT_PCIE_PIO].size,
1, FDT_PCI_RANGE_MMIO,
2, memmap[VIRT_PCIE_MMIO].base,
2, memmap[VIRT_PCIE_MMIO].base, 2, memmap[VIRT_PCIE_MMIO].size);
create_pcie_irq_map(fdt, nodename, plic_phandle);
g_free(nodename);
nodename = g_strdup_printf("/test@%lx",
(long)memmap[VIRT_TEST].base);
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_string(fdt, nodename, "compatible", "sifive,test0");
qemu_fdt_setprop_cells(fdt, nodename, "reg",
0x0, memmap[VIRT_TEST].base,
0x0, memmap[VIRT_TEST].size);
g_free(nodename);
nodename = g_strdup_printf("/uart@%lx",
(long)memmap[VIRT_UART0].base);
qemu_fdt_add_subnode(fdt, nodename);
qemu_fdt_setprop_string(fdt, nodename, "compatible", "ns16550a");
qemu_fdt_setprop_cells(fdt, nodename, "reg",
0x0, memmap[VIRT_UART0].base,
0x0, memmap[VIRT_UART0].size);
qemu_fdt_setprop_cell(fdt, nodename, "clock-frequency", 3686400);
qemu_fdt_setprop_cells(fdt, nodename, "interrupt-parent", plic_phandle);
qemu_fdt_setprop_cells(fdt, nodename, "interrupts", UART0_IRQ);
qemu_fdt_add_subnode(fdt, "/chosen");
qemu_fdt_setprop_string(fdt, "/chosen", "stdout-path", nodename);
if (cmdline) {
qemu_fdt_setprop_string(fdt, "/chosen", "bootargs", cmdline);
}
g_free(nodename);
return fdt;
}
static inline DeviceState *gpex_pcie_init(MemoryRegion *sys_mem,
hwaddr ecam_base, hwaddr ecam_size,
hwaddr mmio_base, hwaddr mmio_size,
hwaddr pio_base,
DeviceState *plic, bool link_up)
{
DeviceState *dev;
MemoryRegion *ecam_alias, *ecam_reg;
MemoryRegion *mmio_alias, *mmio_reg;
qemu_irq irq;
int i;
dev = qdev_create(NULL, TYPE_GPEX_HOST);
qdev_init_nofail(dev);
ecam_alias = g_new0(MemoryRegion, 1);
ecam_reg = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 0);
memory_region_init_alias(ecam_alias, OBJECT(dev), "pcie-ecam",
ecam_reg, 0, ecam_size);
memory_region_add_subregion(get_system_memory(), ecam_base, ecam_alias);
mmio_alias = g_new0(MemoryRegion, 1);
mmio_reg = sysbus_mmio_get_region(SYS_BUS_DEVICE(dev), 1);
memory_region_init_alias(mmio_alias, OBJECT(dev), "pcie-mmio",
mmio_reg, mmio_base, mmio_size);
memory_region_add_subregion(get_system_memory(), mmio_base, mmio_alias);
sysbus_mmio_map(SYS_BUS_DEVICE(dev), 2, pio_base);
for (i = 0; i < GPEX_NUM_IRQS; i++) {
irq = qdev_get_gpio_in(plic, PCIE_IRQ + i);
sysbus_connect_irq(SYS_BUS_DEVICE(dev), i, irq);
gpex_set_irq_num(GPEX_HOST(dev), i, PCIE_IRQ + i);
}
return dev;
}
static void riscv_virt_board_init(MachineState *machine)
{
const struct MemmapEntry *memmap = virt_memmap;
RISCVVirtState *s = g_new0(RISCVVirtState, 1);
MemoryRegion *system_memory = get_system_memory();
MemoryRegion *main_mem = g_new(MemoryRegion, 1);
MemoryRegion *mask_rom = g_new(MemoryRegion, 1);
char *plic_hart_config;
size_t plic_hart_config_len;
int i;
void *fdt;
/* Initialize SOC */
object_initialize_child(OBJECT(machine), "soc", &s->soc, sizeof(s->soc),
TYPE_RISCV_HART_ARRAY, &error_abort, NULL);
object_property_set_str(OBJECT(&s->soc), machine->cpu_type, "cpu-type",
&error_abort);
object_property_set_int(OBJECT(&s->soc), smp_cpus, "num-harts",
&error_abort);
object_property_set_bool(OBJECT(&s->soc), true, "realized",
&error_abort);
/* register system main memory (actual RAM) */
memory_region_init_ram(main_mem, NULL, "riscv_virt_board.ram",
machine->ram_size, &error_fatal);
memory_region_add_subregion(system_memory, memmap[VIRT_DRAM].base,
main_mem);
/* create device tree */
fdt = create_fdt(s, memmap, machine->ram_size, machine->kernel_cmdline);
/* boot rom */
memory_region_init_rom(mask_rom, NULL, "riscv_virt_board.mrom",
memmap[VIRT_MROM].size, &error_fatal);
memory_region_add_subregion(system_memory, memmap[VIRT_MROM].base,
mask_rom);
if (machine->kernel_filename) {
uint64_t kernel_entry = load_kernel(machine->kernel_filename);
if (machine->initrd_filename) {
hwaddr start;
hwaddr end = load_initrd(machine->initrd_filename,
machine->ram_size, kernel_entry,
&start);
qemu_fdt_setprop_cell(fdt, "/chosen",
"linux,initrd-start", start);
qemu_fdt_setprop_cell(fdt, "/chosen", "linux,initrd-end",
end);
}
}
/* reset vector */
uint32_t reset_vec[8] = {
0x00000297, /* 1: auipc t0, %pcrel_hi(dtb) */
0x02028593, /* addi a1, t0, %pcrel_lo(1b) */
0xf1402573, /* csrr a0, mhartid */
#if defined(TARGET_RISCV32)
0x0182a283, /* lw t0, 24(t0) */
#elif defined(TARGET_RISCV64)
0x0182b283, /* ld t0, 24(t0) */
#endif
0x00028067, /* jr t0 */
0x00000000,
memmap[VIRT_DRAM].base, /* start: .dword memmap[VIRT_DRAM].base */
0x00000000,
/* dtb: */
};
/* copy in the reset vector in little_endian byte order */
for (i = 0; i < sizeof(reset_vec) >> 2; i++) {
reset_vec[i] = cpu_to_le32(reset_vec[i]);
}
rom_add_blob_fixed_as("mrom.reset", reset_vec, sizeof(reset_vec),
memmap[VIRT_MROM].base, &address_space_memory);
/* copy in the device tree */
if (fdt_pack(s->fdt) || fdt_totalsize(s->fdt) >
memmap[VIRT_MROM].size - sizeof(reset_vec)) {
error_report("not enough space to store device-tree");
exit(1);
}
qemu_fdt_dumpdtb(s->fdt, fdt_totalsize(s->fdt));
rom_add_blob_fixed_as("mrom.fdt", s->fdt, fdt_totalsize(s->fdt),
memmap[VIRT_MROM].base + sizeof(reset_vec),
&address_space_memory);
/* create PLIC hart topology configuration string */
plic_hart_config_len = (strlen(VIRT_PLIC_HART_CONFIG) + 1) * smp_cpus;
plic_hart_config = g_malloc0(plic_hart_config_len);
for (i = 0; i < smp_cpus; i++) {
if (i != 0) {
strncat(plic_hart_config, ",", plic_hart_config_len);
}
strncat(plic_hart_config, VIRT_PLIC_HART_CONFIG, plic_hart_config_len);
plic_hart_config_len -= (strlen(VIRT_PLIC_HART_CONFIG) + 1);
}
/* MMIO */
s->plic = sifive_plic_create(memmap[VIRT_PLIC].base,
plic_hart_config,
VIRT_PLIC_NUM_SOURCES,
VIRT_PLIC_NUM_PRIORITIES,
VIRT_PLIC_PRIORITY_BASE,
VIRT_PLIC_PENDING_BASE,
VIRT_PLIC_ENABLE_BASE,
VIRT_PLIC_ENABLE_STRIDE,
VIRT_PLIC_CONTEXT_BASE,
VIRT_PLIC_CONTEXT_STRIDE,
memmap[VIRT_PLIC].size);
sifive_clint_create(memmap[VIRT_CLINT].base,
memmap[VIRT_CLINT].size, smp_cpus,
SIFIVE_SIP_BASE, SIFIVE_TIMECMP_BASE, SIFIVE_TIME_BASE);
sifive_test_create(memmap[VIRT_TEST].base);
for (i = 0; i < VIRTIO_COUNT; i++) {
sysbus_create_simple("virtio-mmio",
memmap[VIRT_VIRTIO].base + i * memmap[VIRT_VIRTIO].size,
qdev_get_gpio_in(DEVICE(s->plic), VIRTIO_IRQ + i));
}
gpex_pcie_init(system_memory,
memmap[VIRT_PCIE_ECAM].base,
memmap[VIRT_PCIE_ECAM].size,
memmap[VIRT_PCIE_MMIO].base,
memmap[VIRT_PCIE_MMIO].size,
memmap[VIRT_PCIE_PIO].base,
DEVICE(s->plic), true);
serial_mm_init(system_memory, memmap[VIRT_UART0].base,
0, qdev_get_gpio_in(DEVICE(s->plic), UART0_IRQ), 399193,
serial_hd(0), DEVICE_LITTLE_ENDIAN);
g_free(plic_hart_config);
}
static void riscv_virt_board_machine_init(MachineClass *mc)
{
mc->desc = "RISC-V VirtIO Board (Privileged ISA v1.10)";
mc->init = riscv_virt_board_init;
mc->max_cpus = 8; /* hardcoded limit in BBL */
mc->default_cpu_type = VIRT_CPU;
}
DEFINE_MACHINE("virt", riscv_virt_board_machine_init)