MacOS reads this address to identify the hardware. This is a basic implementation returning the ID of Quadra 800.
Details: http://mess.redump.net/mess/driver_info/mac_technical_notes "There are 3 ID schemes [...] The third and most scalable is a machine ID register at 0x5ffffffc. The top word must be 0xa55a to be valid. Then bits 15-11 are 0 for consumer Macs, 1 for portables, 2 for high-end 68k, and 3 for high-end PowerPC. Bit 10 is 1 if additional ID bits appear elsewhere (e.g. in VIA1). The rest of the bits are a per-model identifier. Model Lower 16 bits of ID ... Quadra/Centris 610/650/800 0x2BAD" Signed-off-by: Laurent Vivier <laur...@vivier.eu> --- hw/m68k/q800.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/hw/m68k/q800.c b/hw/m68k/q800.c index 9ee0cb1141..c2b2aa779f 100644 --- a/hw/m68k/q800.c +++ b/hw/m68k/q800.c @@ -97,6 +97,23 @@ static void main_cpu_reset(void *opaque) cpu->env.pc = ldl_phys(cs->as, 4); } +static uint64_t machine_id_read(void *opaque, hwaddr addr, unsigned size) +{ + return 0xa55a2bad; /* Quadra 800 ID */ +} + +static void machine_id_write(void *opaque, hwaddr addr, uint64_t val, + unsigned size) +{ +} + +static const MemoryRegionOps machine_id_ops = { + .read = machine_id_read, + .write = machine_id_write, + .valid.min_access_size = 4, + .valid.max_access_size = 4, +}; + static void q800_init(MachineState *machine) { M68kCPU *cpu = NULL; @@ -110,6 +127,7 @@ static void q800_init(MachineState *machine) MemoryRegion *rom; MemoryRegion *ram; MemoryRegion *io; + MemoryRegion *machine_id; const int io_slice_nb = (IO_SIZE / IO_SLICE) - 1; int i; ram_addr_t ram_size = machine->ram_size; @@ -159,6 +177,10 @@ static void q800_init(MachineState *machine) g_free(name); } + machine_id = g_malloc(sizeof(*machine_id)); + memory_region_init_io(machine_id, NULL, &machine_id_ops, NULL, "Machine ID", 4); + memory_region_add_subregion(get_system_memory(), 0x5ffffffc, machine_id); + /* djMEMC memory and interrupt controller */ djmemc_dev = qdev_create(NULL, TYPE_DJMEMC); -- 2.23.0