[PATCH 0/3] m68k: virt: add a firmware to the virt machine (petit boot)

[PATCH 0/3] m68k: virt: add a firmware to the virt machine (petit boot)

[Laurent Vivier]

For the moment, the virt machine can only be started by using
QEMU "-kernel" parameter, and thus can only load the kernel/initramfs
from the host filesystem.

Adding a firmware is a good way to allow the machine to boot and update
a kernel from the guest point of view (disk, network, cdrom, ...).

As I don't want to port a firmware to this machine, the easy way to do
that is to use linux. This approach is already in use by petit boot on
the bare metal POWER systems.

This series adds a bootstrap ROM to load the firmware (petit boot),
and a buildroot environment to build the petit boot firmware for
the m68k virt machine.

To build the bootstram ROM:

$ git submodule init roms/m68k-virt
$ git submodule updage roms/m68k-virt
$ make -C roms m68k-virt-bootrom

To build the firmware:

$ git submodule init roms/buildroot
$ git submodule update roms/buildroot
$ make -C roms m68k-virt-firmware

Build qemu-system-m68k and then you can start QEMU and
play with petit boot:
$ ./qemu-system-m68k -M virt -nographic

Petit boot supports various bootloader configuration files, like
grub, pxe, kboot, syslinux...

For instance:

menuentry "Linux 5.16.0-virt (debian 10.0)" {
	search --set=root --label root
	linux /boot/vmlinux-5.16.0-virt ro root=/dev/vda2 console=ttyGF0
}

default="vmlinux-5.16.0-virt"
vmlinux-5.16.0-virt='/boot/vmlinux-5.16.0-virt root=/dev/vda2 console=ttyGF0'

default vmlinux-5.16.0-virt (debian 10.0)
label vmlinux-5.16.0-virt (debian 10.0)
 kernel /boot/vmlinux-5.16.0-virt
 append root=/dev/vda2 console=ttyGF0

Laurent Vivier (3):
  m68k: bootinfo entry size must be aligned on 4 bytes
  m68k: virt: add a bootstrap ROM
  m68k: virt: add a firmware (petitboot)

 configure                   |   3 +-
 hw/m68k/bootinfo.h          |   4 +-
 include/hw/misc/virt_ctrl.h |   6 ++
 hw/m68k/virt.c              |  38 ++++++++++++
 hw/misc/virt_ctrl.c         | 111 +++++++++++++++++++++++++++++++++++-
 .gitmodules                 |   6 ++
 pc-bios/meson.build         |   3 +
 roms/Makefile               |  15 +++++
 roms/buildroot              |   1 +
 roms/m68k-virt              |   1 +
 10 files changed, 183 insertions(+), 5 deletions(-)
 create mode 160000 roms/buildroot
 create mode 160000 roms/m68k-virt

-- 
2.34.1

[PATCH 1/3] m68k: bootinfo entry size must be aligned on 4 bytes

[Laurent Vivier]

This is checked by petitboot.

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 hw/m68k/bootinfo.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/m68k/bootinfo.h b/hw/m68k/bootinfo.h
index adbf0c5521e5..94c97a71fa07 100644
--- a/hw/m68k/bootinfo.h
+++ b/hw/m68k/bootinfo.h
@@ -48,12 +48,12 @@
         stw_phys(as, base, id); \
         base += 2; \
         stw_phys(as, base, \
-                 (sizeof(struct bi_record) + strlen(string) + 2) & ~1); \
+                 (sizeof(struct bi_record) + strlen(string) + 4) & ~3); \
         base += 2; \
         for (i = 0; string[i]; i++) { \
             stb_phys(as, base++, string[i]); \
         } \
         stb_phys(as, base++, 0); \
-        base = (parameters_base + 1) & ~1; \
+        base = (parameters_base + 4) & ~3; \
     } while (0)
 #endif
-- 
2.34.1

[PATCH 2/3] m68k: virt: add a bootstrap ROM

[Laurent Vivier]

This ROM will be started by QEMU and will load the firmware.
The firware will be based on Petit Boot, the aim of the bootstrap
is to ask QEMU to load the kernel and initramfs to the RAM.

It also builds the bootinfo structure to pass to the kernel the
same way QEMU does when it loads directly the kernel.

To build the bootstrap:
$ git submodule init roms/m68k-virt
$ git submodule updage roms/m68k-virt
$ make -C roms m68k-virt-bootrom

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 hw/m68k/virt.c      | 32 ++++++++++++++++++++++++++++++++
 .gitmodules         |  3 +++
 pc-bios/meson.build |  1 +
 roms/Makefile       |  7 +++++++
 roms/m68k-virt      |  1 +
 5 files changed, 44 insertions(+)
 create mode 160000 roms/m68k-virt

diff --git a/hw/m68k/virt.c b/hw/m68k/virt.c
index bbaf630bbf20..11aff6d93865 100644
--- a/hw/m68k/virt.c
+++ b/hw/m68k/virt.c
@@ -10,6 +10,7 @@
 #include "qemu/osdep.h"
 #include "qemu/units.h"
 #include "qemu-common.h"
+#include "qemu/datadir.h"
 #include "sysemu/sysemu.h"
 #include "cpu.h"
 #include "hw/boards.h"
@@ -85,6 +86,13 @@
 #define VIRT_VIRTIO_MMIO_BASE 0xff010000     /* MMIO: 0xff010000 - 0xff01ffff */
 #define VIRT_VIRTIO_IRQ_BASE  PIC_IRQ(2, 1)  /* PIC: 2, 3, 4, 5, IRQ: ALL */
 
+/*
+ * At the end of the memory address space we have a 1 MB ROM
+ */
+#define VIRT_ROM_ADDR 0xfff00000
+#define VIRT_ROM_SIZE 0x00100000
+#define VIRT_ROM_NAME "m68k-virt.rom"
+
 typedef struct {
     M68kCPU *cpu;
     hwaddr initial_pc;
@@ -113,12 +121,16 @@ static void virt_init(MachineState *machine)
     const char *kernel_filename = machine->kernel_filename;
     const char *initrd_filename = machine->initrd_filename;
     const char *kernel_cmdline = machine->kernel_cmdline;
+    const char *bios_name = machine->firmware ?: VIRT_ROM_NAME;
     hwaddr parameters_base;
     DeviceState *dev;
     DeviceState *irqc_dev;
     DeviceState *pic_dev[VIRT_GF_PIC_NB];
     SysBusDevice *sysbus;
     hwaddr io_base;
+    MemoryRegion *rom;
+    int bios_size;
+    char *filename;
     int i;
     ResetInfo *reset_info;
 
@@ -207,6 +219,19 @@ static void virt_init(MachineState *machine)
         io_base += 0x200;
     }
 
+    /* Load ROM */
+    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, bios_name);
+    if (filename) {
+        rom = g_malloc(sizeof(*rom));
+        memory_region_init_rom(rom, NULL, "m68k-virt.rom", VIRT_ROM_SIZE,
+                           &error_abort);
+        memory_region_add_subregion(get_system_memory(), VIRT_ROM_ADDR, rom);
+        bios_size = load_image_targphys(filename, VIRT_ROM_ADDR, VIRT_ROM_SIZE);
+    } else {
+        bios_size = -1;
+    }
+
+    /* Load kernel if needed */
     if (kernel_filename) {
         CPUState *cs = CPU(cpu);
         uint64_t high;
@@ -265,6 +290,13 @@ static void virt_init(MachineState *machine)
             initrd_size = 0;
         }
         BOOTINFO0(cs->as, parameters_base, BI_LAST);
+    } else {
+        if (bios_size != VIRT_ROM_SIZE) {
+            error_report("ROM not found (%s) and no kernel provided",
+                         bios_name);
+            exit(EXIT_FAILURE);
+        }
+        reset_info->initial_pc = VIRT_ROM_ADDR;
     }
 }
 
diff --git a/.gitmodules b/.gitmodules
index 84425d87e28a..315d597d057a 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -67,3 +67,6 @@
 [submodule "tests/lcitool/libvirt-ci"]
 	path = tests/lcitool/libvirt-ci
 	url = http://gitlab.com/libvirt/libvirt-ci
+[submodule "roms/m68k-virt"]
+	path = roms/m68k-virt
+	url = https://github.com/vivier/m68k-virt-bootstrap.git
diff --git a/pc-bios/meson.build b/pc-bios/meson.build
index 4ac7a5509b69..ffec6decdc4c 100644
--- a/pc-bios/meson.build
+++ b/pc-bios/meson.build
@@ -81,6 +81,7 @@ blobs = files(
   'opensbi-riscv32-generic-fw_dynamic.bin',
   'opensbi-riscv64-generic-fw_dynamic.bin',
   'npcm7xx_bootrom.bin',
+  'm68k-virt.rom',
 )
 
 if get_option('install_blobs')
diff --git a/roms/Makefile b/roms/Makefile
index 5e44d9789001..f9f84e8efb1b 100644
--- a/roms/Makefile
+++ b/roms/Makefile
@@ -40,6 +40,7 @@ powerpc_cross_prefix := $(call find-cross-prefix,powerpc)
 x86_64_cross_prefix := $(call find-cross-prefix,x86_64)
 riscv32_cross_prefix := $(call find-cross-prefix,riscv32)
 riscv64_cross_prefix := $(call find-cross-prefix,riscv64)
+m68k_cross_prefix := $(call find-cross-prefix,m68k)
 
 # tag our seabios builds
 SEABIOS_EXTRAVERSION="-prebuilt.qemu.org"
@@ -69,6 +70,7 @@ default help:
 	@echo "  opensbi32-generic  -- update OpenSBI for 32-bit generic machine"
 	@echo "  opensbi64-generic  -- update OpenSBI for 64-bit generic machine"
 	@echo "  qboot              -- update qboot"
+	@echo "  m68k-virt-bootrom  -- update m68k-virt bootrom"
 	@echo "  clean              -- delete the files generated by the previous" \
 	                              "build targets"
 
@@ -197,6 +199,10 @@ npcm7xx_bootrom:
 	$(MAKE) -C vbootrom CROSS_COMPILE=$(arm_cross_prefix)
 	cp vbootrom/npcm7xx_bootrom.bin ../pc-bios/npcm7xx_bootrom.bin
 
+m68k-virt-bootrom:
+	$(MAKE) -C m68k-virt CROSS_COMPILE=$(m68k_cross_prefix)
+	cp m68k-virt/rom.bin ../pc-bios/m68k-virt.rom
+
 clean:
 	rm -rf seabios/.config seabios/out seabios/builds
 	$(MAKE) -C sgabios clean
@@ -211,3 +217,4 @@ clean:
 	$(MAKE) -C opensbi clean
 	$(MAKE) -C qboot clean
 	$(MAKE) -C vbootrom clean
+	$(MAKE) -C m68k-virt clean
diff --git a/roms/m68k-virt b/roms/m68k-virt
new file mode 160000
index 000000000000..f2a4daa7cd11
--- /dev/null
+++ b/roms/m68k-virt
@@ -0,0 +1 @@
+Subproject commit f2a4daa7cd11d35fa48236653211897b50977144
-- 
2.34.1

[PATCH 3/3] m68k: virt: add a firmware (petitboot)

[Laurent Vivier]

Add a firmware for the m68k virt machine

The firmware is based on petit boot (also used in bare metal POWER
systems)

Petit boot is embedded in a buildroot filesystem.

This patch define the buildroot repository, add make targets to
build and install the kernel and filesystem produced by buildroot.

To build the firmware:

$ git submodule init roms/buildroot
$ git submodule update roms/buildroot
$ make -C roms m68k-virt-firmware

Signed-off-by: Laurent Vivier <laurent@vivier.eu>
---
 configure                   |   3 +-
 include/hw/misc/virt_ctrl.h |   6 ++
 hw/m68k/virt.c              |  12 +++-
 hw/misc/virt_ctrl.c         | 111 +++++++++++++++++++++++++++++++++++-
 .gitmodules                 |   3 +
 pc-bios/meson.build         |   2 +
 roms/Makefile               |   8 +++
 roms/buildroot              |   1 +
 8 files changed, 140 insertions(+), 6 deletions(-)
 create mode 160000 roms/buildroot

diff --git a/configure b/configure
index e6cfc0e4be6c..5cc3d7029455 100755
--- a/configure
+++ b/configure
@@ -3685,7 +3685,8 @@ for bios_file in \
     $source_path/pc-bios/openbios-* \
     $source_path/pc-bios/u-boot.* \
     $source_path/pc-bios/palcode-* \
-    $source_path/pc-bios/qemu_vga.ndrv
+    $source_path/pc-bios/qemu_vga.ndrv \
+    $source_path/pc-bios/m68k-virt.*
 
 do
     LINKS="$LINKS pc-bios/$(basename $bios_file)"
diff --git a/include/hw/misc/virt_ctrl.h b/include/hw/misc/virt_ctrl.h
index 25a237e51874..e1a3f027ab03 100644
--- a/include/hw/misc/virt_ctrl.h
+++ b/include/hw/misc/virt_ctrl.h
@@ -17,6 +17,12 @@ struct VirtCtrlState {
     qemu_irq irq;
 
     uint32_t irq_enabled;
+
+    MachineState *machine;
+    char *fw_elf;
+    char *fw_ramfs;
+    uint32_t fw_bootinfo_size;
+    uint8_t *fw_bootinfo;
 };
 
 #endif
diff --git a/hw/m68k/virt.c b/hw/m68k/virt.c
index 11aff6d93865..d6af84d1a3f6 100644
--- a/hw/m68k/virt.c
+++ b/hw/m68k/virt.c
@@ -89,9 +89,11 @@
 /*
  * At the end of the memory address space we have a 1 MB ROM
  */
-#define VIRT_ROM_ADDR 0xfff00000
-#define VIRT_ROM_SIZE 0x00100000
-#define VIRT_ROM_NAME "m68k-virt.rom"
+#define VIRT_ROM_ADDR      0xfff00000
+#define VIRT_ROM_SIZE      0x00100000
+#define VIRT_ROM_NAME      "m68k-virt.rom"
+#define VIRT_FW_ELF_NAME   "m68k-virt.vmlinux"
+#define VIRT_FW_RAMFS_NAME "m68k-virt.petitboot"
 
 typedef struct {
     M68kCPU *cpu;
@@ -202,6 +204,10 @@ static void virt_init(MachineState *machine)
 
     /* virt controller */
     dev = qdev_new(TYPE_VIRT_CTRL);
+    object_property_set_link(OBJECT(dev), "machine", OBJECT(machine),
+                             &error_abort);
+    qdev_prop_set_string(dev, "fw.elf", VIRT_FW_ELF_NAME);
+    qdev_prop_set_string(dev, "fw.ramfs", VIRT_FW_RAMFS_NAME);
     sysbus = SYS_BUS_DEVICE(dev);
     sysbus_realize_and_unref(sysbus, &error_fatal);
     sysbus_mmio_map(sysbus, 0, VIRT_CTRL_MMIO_BASE);
diff --git a/hw/misc/virt_ctrl.c b/hw/misc/virt_ctrl.c
index e75d1e7e17b3..2ac725f1570b 100644
--- a/hw/misc/virt_ctrl.c
+++ b/hw/misc/virt_ctrl.c
@@ -5,28 +5,98 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu/datadir.h"
 #include "hw/qdev-properties.h"
 #include "hw/sysbus.h"
+#include "hw/loader.h"
+#include "hw/boards.h"
 #include "migration/vmstate.h"
 #include "qemu/log.h"
 #include "trace.h"
+#include "elf.h"
 #include "sysemu/runstate.h"
 #include "hw/misc/virt_ctrl.h"
 
 enum {
     REG_FEATURES = 0x00,
     REG_CMD      = 0x04,
+    REG_PARAM    = 0x08,
 };
 
 #define FEAT_POWER_CTRL 0x00000001
+#define FEAT_FW_CTRL    0x00000002
+
+#define FEAT_SUPPORTED (FEAT_POWER_CTRL | FEAT_FW_CTRL)
 
 enum {
+    /* Power Control */
     CMD_NOOP,
     CMD_RESET,
     CMD_HALT,
     CMD_PANIC,
+    /* Firmware Control */
+    CMD_FW_MACHINE_ID,
+    CMD_FW_LOAD,
+    CMD_FW_RAMSIZE,
+    CMD_FW_QEMU_VERSION
+};
+
+enum {
+   FW_M68K,
 };
 
+static uint32_t param;
+
+#define RESULT_ERROR (-1)
+
+static uint32_t fw_load_m68k(VirtCtrlState *s)
+{
+    char *elf_filename, *ramfs_filename;
+    int32_t kernel_size;
+    uint64_t elf_entry, high;
+    int32_t ramfs_size;
+    ram_addr_t ramfs_base;
+    void *ram_ptr;
+
+    elf_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, s->fw_elf);
+    if (elf_filename == NULL) {
+        error_report("Cannot find %s", s->fw_elf);
+        return RESULT_ERROR;
+    }
+    ramfs_filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, s->fw_ramfs);
+    if (ramfs_filename == NULL) {
+        error_report("Cannot find %s", s->fw_ramfs);
+        return RESULT_ERROR;
+    }
+
+    kernel_size = load_elf_ram(elf_filename, NULL, NULL, NULL,
+                               &elf_entry, NULL, &high, NULL, 1,
+                               EM_68K, 0, 0, NULL, false);
+    if (kernel_size < 0) {
+        error_report("could not load kernel '%s'", elf_filename);
+        return RESULT_ERROR;
+    }
+
+    ramfs_size = get_image_size(ramfs_filename);
+    if (ramfs_size < 0) {
+        error_report("could not load initial ram disk '%s'",
+                     ramfs_filename);
+        return RESULT_ERROR;
+    }
+
+    ram_ptr = memory_region_get_ram_ptr(s->machine->ram);
+
+    ramfs_base = (s->machine->ram_size - ramfs_size) & ~0xfff;
+    load_image_size(ramfs_filename, ram_ptr + ramfs_base, ramfs_size);
+
+    high = (high + 1) & ~1;
+    *(uint32_t *)(ram_ptr + high) = cpu_to_be32(elf_entry);
+    *(uint32_t *)(ram_ptr + high + 4) = cpu_to_be32(ramfs_base);
+    *(uint32_t *)(ram_ptr + high + 8) = cpu_to_be32(ramfs_size);
+
+    return high;
+}
+
 static uint64_t virt_ctrl_read(void *opaque, hwaddr addr, unsigned size)
 {
     VirtCtrlState *s = opaque;
@@ -34,7 +104,10 @@ static uint64_t virt_ctrl_read(void *opaque, hwaddr addr, unsigned size)
 
     switch (addr) {
     case REG_FEATURES:
-        value = FEAT_POWER_CTRL;
+        value = FEAT_SUPPORTED;
+        break;
+    case REG_PARAM:
+        value = param;
         break;
     default:
         qemu_log_mask(LOG_UNIMP,
@@ -43,7 +116,7 @@ static uint64_t virt_ctrl_read(void *opaque, hwaddr addr, unsigned size)
         break;
     }
 
-    trace_virt_ctrl_write(s, addr, size, value);
+    trace_virt_ctrl_read(s, addr, size, value);
 
     return value;
 }
@@ -69,8 +142,32 @@ static void virt_ctrl_write(void *opaque, hwaddr addr, uint64_t value,
         case CMD_PANIC:
             qemu_system_shutdown_request(SHUTDOWN_CAUSE_GUEST_PANIC);
             break;
+        case CMD_FW_LOAD:
+            switch (param) {
+            case FW_M68K:
+                param = fw_load_m68k(s);
+                break;
+            default:
+                qemu_log_mask(LOG_UNIMP, "%s: unimplemented FW type %d\n",
+                              __func__, param);
+                break;
+            }
+            break;
+        case CMD_FW_RAMSIZE:
+            param = s->machine->ram_size;
+            break;
+        case CMD_FW_QEMU_VERSION:
+            param = (QEMU_VERSION_MAJOR << 24) | (QEMU_VERSION_MINOR << 16) |
+                    (QEMU_VERSION_MICRO << 8);
+            break;
+        case CMD_FW_MACHINE_ID:
+            param = 0;
+            break;
         }
         break;
+    case REG_PARAM:
+        param = value;
+        break;
     default:
         qemu_log_mask(LOG_UNIMP,
                       "%s: unimplemented register write 0x%02"HWADDR_PRIx"\n",
@@ -114,6 +211,14 @@ static const VMStateDescription vmstate_virt_ctrl = {
     }
 };
 
+static Property virt_ctl_properties[] = {
+    DEFINE_PROP_LINK("machine", VirtCtrlState, machine,
+                     TYPE_MACHINE, MachineState *),
+    DEFINE_PROP_STRING("fw.elf", VirtCtrlState, fw_elf),
+    DEFINE_PROP_STRING("fw.ramfs", VirtCtrlState, fw_ramfs),
+    DEFINE_PROP_END_OF_LIST(),
+};
+
 static void virt_ctrl_instance_init(Object *obj)
 {
     SysBusDevice *dev = SYS_BUS_DEVICE(obj);
@@ -132,6 +237,8 @@ static void virt_ctrl_class_init(ObjectClass *oc, void *data)
     dc->reset = virt_ctrl_reset;
     dc->realize = virt_ctrl_realize;
     dc->vmsd = &vmstate_virt_ctrl;
+
+    device_class_set_props(dc, virt_ctl_properties);
 }
 
 static const TypeInfo virt_ctrl_info = {
diff --git a/.gitmodules b/.gitmodules
index 315d597d057a..b45269f896cf 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -70,3 +70,6 @@
 [submodule "roms/m68k-virt"]
 	path = roms/m68k-virt
 	url = https://github.com/vivier/m68k-virt-bootstrap.git
+[submodule "roms/buildroot"]
+	path = roms/buildroot
+	url = https://github.com/vivier/buildroot.git
diff --git a/pc-bios/meson.build b/pc-bios/meson.build
index ffec6decdc4c..c94b63d17d7b 100644
--- a/pc-bios/meson.build
+++ b/pc-bios/meson.build
@@ -82,6 +82,8 @@ blobs = files(
   'opensbi-riscv64-generic-fw_dynamic.bin',
   'npcm7xx_bootrom.bin',
   'm68k-virt.rom',
+  'm68k-virt.vmlinux',
+  'm68k-virt.petitboot',
 )
 
 if get_option('install_blobs')
diff --git a/roms/Makefile b/roms/Makefile
index f9f84e8efb1b..8275083444ef 100644
--- a/roms/Makefile
+++ b/roms/Makefile
@@ -71,6 +71,7 @@ default help:
 	@echo "  opensbi64-generic  -- update OpenSBI for 64-bit generic machine"
 	@echo "  qboot              -- update qboot"
 	@echo "  m68k-virt-bootrom  -- update m68k-virt bootrom"
+	@echo "  m68k-virt-firmware -- update m68k-virt firmware (petitboot)"
 	@echo "  clean              -- delete the files generated by the previous" \
 	                              "build targets"
 
@@ -203,6 +204,12 @@ m68k-virt-bootrom:
 	$(MAKE) -C m68k-virt CROSS_COMPILE=$(m68k_cross_prefix)
 	cp m68k-virt/rom.bin ../pc-bios/m68k-virt.rom
 
+m68k-virt-firmware:
+	$(MAKE) -C buildroot qemu_m68k_virt_petitboot_defconfig
+	$(MAKE) -C buildroot -j $$(( $$(getconf _NPROCESSORS_ONLN) * 2 + 1))
+	cp buildroot/output/images/vmlinux ../pc-bios/m68k-virt.vmlinux
+	cp buildroot/output/images/rootfs.cpio.xz ../pc-bios/m68k-virt.petitboot
+
 clean:
 	rm -rf seabios/.config seabios/out seabios/builds
 	$(MAKE) -C sgabios clean
@@ -218,3 +225,4 @@ clean:
 	$(MAKE) -C qboot clean
 	$(MAKE) -C vbootrom clean
 	$(MAKE) -C m68k-virt clean
+	$(MAKE) -C buildroot clean
diff --git a/roms/buildroot b/roms/buildroot
new file mode 160000
index 000000000000..5590654699e4
--- /dev/null
+++ b/roms/buildroot
@@ -0,0 +1 @@
+Subproject commit 5590654699e4926bee834ae99f90c8062bc418eb
-- 
2.34.1

Re: [PATCH 2/3] m68k: virt: add a bootstrap ROM

[Philippe Mathieu-Daudé via]

On 2/2/22 23:35, Laurent Vivier wrote:
> This ROM will be started by QEMU and will load the firmware.
> The firware will be based on Petit Boot, the aim of the bootstrap

"firmware"

> is to ask QEMU to load the kernel and initramfs to the RAM.
> 
> It also builds the bootinfo structure to pass to the kernel the
> same way QEMU does when it loads directly the kernel.
> 
> To build the bootstrap:
> $ git submodule init roms/m68k-virt
> $ git submodule updage roms/m68k-virt

"update"

You can combine as "update --init".

> $ make -C roms m68k-virt-bootrom
> 
> Signed-off-by: Laurent Vivier <laurent@vivier.eu>
> ---
>   hw/m68k/virt.c      | 32 ++++++++++++++++++++++++++++++++
>   .gitmodules         |  3 +++
>   pc-bios/meson.build |  1 +
>   roms/Makefile       |  7 +++++++
>   roms/m68k-virt      |  1 +
>   5 files changed, 44 insertions(+)
>   create mode 160000 roms/m68k-virt

> diff --git a/.gitmodules b/.gitmodules
> index 84425d87e28a..315d597d057a 100644
> --- a/.gitmodules
> +++ b/.gitmodules
> @@ -67,3 +67,6 @@
>   [submodule "tests/lcitool/libvirt-ci"]
>   	path = tests/lcitool/libvirt-ci
>   	url = http://gitlab.com/libvirt/libvirt-ci
> +[submodule "roms/m68k-virt"]
> +	path = roms/m68k-virt
> +	url = https://github.com/vivier/m68k-virt-bootstrap.git

We'll need to mirror that on gitlab.

Otherwise LGTM.